15th International Congress on Neuromuscular Diseases, July 6 - 10, 2018 Vienna, Austria

PL 1.1 / #155PATHOMECHANISMS

Topic: 01. Muscle

Volker Straub

John Walton Muscular Dystrophy Research Centre, Newcastle University, Institute of Genetic Medicine, Newcastle Upon Tyne, GB

Abstract: Traditionally a skeletal muscle is viewed as a distinct anatomical structure that is attached to bone by its tendons, is innervated by a nerve and generates movement through contraction. This simplistic view does highlight the most important physiological function of muscle, force generation through activity of its main molecular structure, the sarcomere. But rather than being defined by its anatomical structure, skeletal muscle is now viewed as a complex organ system consisting of about 700 muscles that make up roughly 40% of our body weight. The skeletal muscular system doesn’t just permit movement of the body and maintains it posture, but supports vital metabolic functions, contributes to temperature control and circulation, interacts with focal and systemic hormonal pathways, and is a crucial contributor to respiratory function and the operation of our senses. Through the application of –omics technologies we have also learned that skeletal muscle tissue itself is far less homogenous than originally anticipated. Distinct skeletal muscles show different transcriptomes and proteomes, despite the fact that their mechanical functions may be very similar. The complexity of normal muscle function is reflected in the broad spectrum of clinical symptoms and muscle pathology when something goes wrong. Over the past 30 years, since the discovery of dystrophin and the characterisation of the DMD gene, >500 different genes leading to about 900 distinct genetic neuromuscular disease have been described. Trying to identify and understand the pathomechanisms that specifically underlie genetic muscle diseases has helped to better characterize the relevant molecular pathways and subcellular structures that are involved in maintaining muscle fibre integrity and function. Not surprisingly we distinguish metabolic muscle disease from structural muscle disease, including diseases that affect the integrity of the sarcolemma, the sarcomere or the nuclear lamina. But although classification systems based on pathomechanistic concepts have been helpful to both basic and clinical scientists, the application of a large array of new molecular imaging and –omics technologies have illustrated the complexity of disease mechanisms and continue to blur the boundaries between pathway-based modelling approaches and our anatomical view of muscle fibre architecture. The responsiveness of the muscular system to damage caused by pathogenetic mechanism is in the end limited and will result in muscle wasting and weakness, the main symptoms of genetic muscle diseases

PL 1.2 / #100INFLAMMATORY MECHANISMS

Topic: 01. Muscle

Andrew Mammen

NIAMS/NIH, Bethesda, US

Abstract not received.

PL 1.3 / #94GENETICS / EPIGENETICS

Topic: 01. Muscle

Hanns Lochmüller

Institute Of Genetic Medicine, Newcastle University, International Centre for Life, Newcastle Upon Tyne, US

Abstract not received.

PL 2.1 / #140INHERITED NEUROPATHIES: FROM GENES TO CLINICAL PHENOTYPE

Topic: 02. Neuropathy

Mary Reilly

Queen Square, Institue Of Neurology, London, GB

Abstract: The inherited neuropathies are a heterogeneous group of disorders encompassing those disorders in which the neuropathy is the sole manifestation and those neuropathies where the neuropathy is part of a more complex neurological or multisystem disorder. The first group includes Charcot Marie Tooth disease (CMT) and the related disorders, the hereditary sensory neuropathies (HSN) and the distal hereditary motor neuropathies (HMN). The second group includes a wide range of disorders examples of which include the leuokodystrophies and the mitochondrial diseases. We now know that there is overlap between the causative genes for CMT, HSN and HMN and often use the term CMT to include all of these diseases. Next generation sequencing especially whole exome and whole genome analysis has also revealed that genes that were associated with other neurological diseases e.g. hereditary spastic paraparesis and the ataxias can sometimes cause CMT or start with a CMT like syndrome before evolving to a more classical disease. Traditionally we have approached the diagnosis of an inherited neuropathy with careful phenotyping to guide us in selecting genetic tests. Although this is still important, increasingly we are using phenotyping to validate variants identified by next generation sequencing. As well as clinical examination and neurophysiology, we use MRI increasingly both of the CNS in complex neuropathies and neuromuscular protocols of the limbs looking for patterns of denervation associated with certain neuropathies (e.g. sparing of adductors and semitendinosus in the thighs of patients with BICD2 and Dynein mutations). The phenotypes associated with individual genes are expanding rapidly but for the common genes certain patterns are common and therefore helpful in validating variants (e.g. early ankle plantar flexion weakness in HSPB1 and HSPB8 mutations). Understanding the detailed phenotypes is critical in therapy development. It is an exciting time in inherited neuropathy therapy development with the ­advent of genetic therapies including antisense, silencing RNA, viral delivered gene therapies and various gene editing therapies. All of these are either in preclinical or clinical trials for various neuropathies. For gene therapies knowing both what tissues need to be targeted for efficacy and which organs needed to be avoided to prevent side effects is important. We also need better ways to monitor disease progression so responsive outcome measures can be developed for clinical trials. While we may have started with detailed phenotyping of families many decades ago to identify causative genes, the mechanistic insights from these genes and the subsequent therapies being developed have led us back to the patients to delineate and understand the phenotypes better in order to be able to perform clinical trials and deliver efficacious therapies to our patients safely.

PL 2.2 / #167IMMUNE MEDIATED NEUROPATHIES: AN EXPANDING FIELD OF TREATABLE NEUROPATHIES

Topic: 02. Neuropathy

Pieter Van Doorn

Center For Lysosomal And Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, NL

Abstract: Immune mediated neuropathies comprise an extending field of disorders with specific subgroups. Patients with these disorders need to be diagnosed because they are treatable. It ranges from the Guillain-Barré syndrome (GBS), a heterogeneous acute polyneuropathy to the more chronic - often demyelinating -polyradiculoneuropathies, of which chronic inflammatory demyelinating polyneuropathy (CIDP) is the most prominent one. CIDP can be divided into the most often occurring symmetric sensory-motor variant, and the pure motor or sensory subgroups. Focal, or multifocal varieties of CIDP are known as Lewis-Sumner syndrome or multifocal acquired demyelinating sensory-motor neuropathy (MADSAM). There additionally is a variety named distal acquired demyelinating sensory neuropathy (DADS). Careful electrophysiological investigation (EMG) and the use of peripheral nerve ultrasound or MRI of the plexus can be helpful to diagnose these patients. EAN/Peripheral Nerve Society guidelines for the diagnosis and treatment of GBS and CIDP are available or under construction. Intravenous immunoglobulin (IVIg) and plasma exchange (PE) are effective in GBS. There is now an indication that complement inhibition using eculizumab potentially potentially is effective in GBS, but additional studies are required. The results of the second-dose IVIg RCT (SID-GBS) conducted in GBS patients with a poor prognosis - based upon the mEGOS prognostic model - are eagerly awaited. An interesting new study that especially may be helpful in low-income countries studied the feasibility of small volume plasma exchange as an alternative and simple method for treatment of GBS.Patients within the spectrum of CIDP can be treated with IVIg, PE or steroids. If one of these proven effective treatments fails, one of these other treatments is still likely to be successful. A recent RCT showed that patients with CIDP can also be treated with subcutaneous IgG (ScIG). There is debate what treatment for CIDP is best. IVIg acts fast but is expensive, and steroids are cheap but can induce major side effects. Pulse steroid treatment however may have a higher chance to induce remission of disease, which is now investigated in new studies. Under- and over treatment are important, therefore it needs to be investigated at least once every 6-12 months if a patient still requires treatment because the disease can get into remission either therapeutically induced or spontaneously. Multifocal motor neuropathy (MMN) is a disorder that may mimic motor neuron disease, but is an IVIg treatable condition. Surprisingly these patients do not improve after steroids or PE. Other important immune-mediated neuropathies are related to the presence of a paraprotein or for example due to vasculitis.A comprehensive overview will be given and the latest developments will be discussed.

PL 2.3 / #55ADVANCES IN THE TREATMENT OF PERIPHERAL NEUROPATHY

Topic: 02. Neuropathy

David Cornblath

Johns Hopkins Medicine, Baltimore, US

Abstract not received.

PL 3.1 / #97EMERGING THERAPIES FOR MOTOR NEURONE DISEASES

Topic: 03. Motor Neurone

Albert Ludolph

Universitätsklinikum Ulm, Ulm, DE

Abstract not received.

PL 3.2 / #164CLINICAL CONCEPT OF ALS

Topic: 03. Motor Neurone

Leonard Van Den Berg

Department Of Neurology, University Medical Center Utrecht, Utrecht, NL

Abstract not received.

PL 3.3 / #182ETHICAL ISSUES

Topic: 03. Motor Neurone

David J. Oliver

Tizard Centre, University of Kent, Canterbury, GB

Background: The care of a person with Motor Neurone Disease is often complex, as they face multiple issues – physical, psychosocial and spiritual. Within these issues are often complex ethical issues, involving difficult discussions with patient and family and within the multidisciplinary team. Careful discussion and consideration of the issues is needed, to enable patients and families to make the most appropriate decision. Methods: A review of the literature, combined with clinical experience, has been undertaken. Results: The ethical issues may occur throughout the disease progression: - At diagnosis The telling of the diagnosis may raise issues – particularly if the family is resistant to telling a patient, who has capacity and is asking for information, or the patient has lost capacity Many patients may now have genetic testing and there are issues as to how they react to knowing that they have a gene mutation.This may influence their future and family plans and they face a dilemma as to what to tell other family member who may be at risk of having the same mutation - When swallowing problems start and become more difficult consideration maybe given to the insertion of a gastrostomy. This discussion may occur when respiratory function is deteriorating. A gastrostomy may improve quality of life, and maybe survival but patients may find the change in feeding very difficult to cope with - Ventilatory support – non-invasive ventilation and, on occasions, invasive ventilation with a tracheostomy - may be considered if respiratory failure develops. Although these interventions may improve symptoms the disease progresses and the patient faces increasing disability, and even the risk of becoming locked in – with no communication. These issues need to be discussed before starting the intervention - At the end of life patients may request treatment withdrawal, such as withdrawal of ventilatory support. There may be complex discussion between family members and team members, who may understand these ethical dilemmas in a different way - Some patients, and families, may ask about assisted dying. In some countries this may be an option – of euthanasia or physician assisted suicide – and there are ethical issues balancing the wishes of the patient and family. In many countries there is no option, but the issue raises discussion for all concerned. Throughout the care of a person with MND there is the need to assess mental capacity to make decisions. As there is increasing evidence that up to 15% of patients may develop fronto-temporal dementia and a further 35% may show evidence of frontal lobe dysfunction, which may affect decision making, these issues have profound implications. Conclusion: Ethical issues need to be considered carefully for all patients with MND throughout the disease progression and involves careful discussion between patient and family and all members of the wider multidisciplinary team.

PL 4.1 / #47PHYSIOLOGY AND STRUCTURE

Topic: 04. Neuromuscular Junction

Steve Burden

Skirball Institute, Nyu Medical School, New York, US

Abstract not received.

PL 4.2 / #121CONGENITAL MYASTHENIC SYNDROMES - NEW GENES AND BETTER TREATMENTS / ANTIBODIES

Topic: 04. Neuromuscular Junction

Kinji Ohno

Nagoya University Graduate School of Medicine, Nagoya, JP

Abstract not received.

PL 4.3 / #171AUTOIMMUNITY

Topic: 04. Neuromuscular Junction

Angela Vincent

Dep. Of Clinical Neuroscience, University of Oxford, Nuffield, Oxford, GB

Abstract: In the 1970s, myasthenia gravis was shown to be caused by antibodies to the acetylcholine receptors (AChRs) on the postsynaptic surface of the neuromuscular junction (NMJ). The mechanisms of AChR antibodies include internalisation of AChRs caused by divalent antibodies, complement-mediated lysis of the postsynaptic membrane, and less common direct inhibition of AChR function. Together, and variably, these cause loss of AChR numbers or function. The weakness is caused by failure of the endplate potential to reach the critical threshold for activation of the compound muscle action potential. This is compounded by the loss of postsynaptic folds where the voltage gated sodium channels that initiate the action potential, are situated. Interestingly, the presynaptic nerve terminal and the postsynaptic muscle both ”compensate” for the defect in transmission by upregulating acetylcholine release and AChR synthesis respectively. There are different subtypes of MG, with thymectomy of established benefit in the young-onset patients, but an increasing number of late-onset patients (>50 years at onset) who often have co-morbidities and present a challenge. Some of the patients who do not have AChR antibodies by conventional assays, have antibodies that only bind detectably to ”clustered AChRs” expressed on cell lines. This emphasises the importance of clustering of AChRs at the NMJ and for synaptic function in general. Some of these patients do not have EMG evidence of MG and are less severe but respond well to immunotherapies. In 2001, antibodies to MuSK were found in some of the myasthenia patients who were negative for AChR antibodies (seronegative MG); these patients often have marked bulbar and facial involvement which can be difficult to treat with the immunotherapies as used for AChR-MG. The MuSK antibodies are predominantly, but not exclusively, IgG4 and the anti-CD20 drug, rituximab, appears to work well in many MuSK-MG patients. More recently antibodies to another NMJ protein, LRP4, have been found in a small number of additional patients. MuSK and LRP4 are both postsynaptic membrane proteins that are responsible for the agrin-induced clustering of the AChRs at the neuromuscular junction. When LRP4 binds agrin, MuSK is activated, DOK7 binds and this begins a sequence of intracellular events that maintain the high density of AChRs at the NMJ. Anything that interferes with LRP4 or MuSK membrane molecules would be expected to lead to dispersal of AChRs, but the detailed mechanisms are still not fully explored. A better understanding could lead to novel pharmacological treatments as will be described. Koneczny I, Cossins J, Vincent A. The role of muscle-specific tyrosine kinase (MuSK) and mystery of MuSK myasthenia gravis. J Anat. 2014 Jan;224(1):29-35. Huda S, Cao M et al. Increased phosphorylation of MuSK provides a potential therapy for MuSK-Ab myasthenia gravis. 2018 submitted for publication.

SS 1.1 / #38TREATMENT STRATEGIES IN GNE MYOPATHY

Topic: 01. Muscle

Zohar Argov

Hebrew University of Jerusalem EKMD, Jerusalem, IL

Background: Introduction: GNE myopathy (previously known as HIBM or DMRV) is associated with mutations in the gne gene, a bifunctional key enzyme in synthesis of sialic acid (neuraminic acid).As a result a progressive distal myopathy with relative quadriceps sparing is observed. The typical histopathology is composed of ‘rimmed vacuoles’, which are autophagic vacuoles. Background: The degree of reduction in enzyme activity ranges between 30-60%. Hyposialylation of muscle is observed in transgenic animal model, but is not consistently found in affected human muscle. It is possible that GNE myopathy is caused by additional mechanisms apart from metabolic deficiency. Methods: The degree of reduction in enzyme activity ranges between 30-60%. Hyposialylation of muscle is observed in transgenic animal model, but is not consistently found in affected human muscle. It is possible that GNE myopathy is caused by additional mechanisms apart from metabolic deficiency. Results: 1. In the mouse model supplementation with sialic acid or its metabolic derivatives led to improvement. 2. In a phase 3 trial in patients receiving 6 gr/day of sialic acid for 1 year, no change in muscle power was found. A phase 2 trial with the metabolic intermediate ManNac is ongoing. 3. An AAV-GNE construct was shown to deliver normal human GNE to muscle in normal and diseased animals, with persistence for prolonged period. A human trial is in preparation. Conclusion: Discussion: supplementation of sialic acid or its derivatives may not suffice to correct the muscle disease. Viral mediated gene therapy may be more suitable at this stage when basic mechanism is still controversial. In the meantime trials with medication affecting autophagy or other downstream processes should be encouraged.

SS 1.2 / #283UPDATE OF RNA-BASED NMD THERAPIES

Topic: 01. Muscle

Kanneboyina Nagaraju

Pharmaceutical Sciences, SUNY-Binghamton University, Binghamton, NY, US

Background: Recent advances in genetics and genomics significantly enhanced our ability to manipulate gene expression at RNA level in vitro in cell culture conditions and in vivo in mouse models and in patients with neuromuscular diseases (NMDs). Methods: The US Food and Drug Administration (FDA) recently approved Exondys 51 (eteplirsen), a drug that specifically targets Exon 51 to induce its exclusion in dystrophin mRNA resulting in a truncated functional dystrophin protein. Efforts are currently underway to target different exons in Duchenne Muscular Dystrophy using different chemistries to enhance efficiency of dystrophin protein expression in skeletal and cardiac muscle. Results: This presentation will briefly cover various RNA targeting approaches (Exon exclusion, inclusion, exchange, altering mRNA decay and stop codon read through), stage of their current development and potential scientific, regulatory and ethical hurdles involved in developing these drugs for Neuromuscular diseases. Conclusion: The potential for RNA based approaches to treat NMDs is excellent.

SS 1.3 / #59PROGRESS IN THE TREATMENT OF IDIOPATHIC INFLAMMATORY MYOPATHIES?

Topic: 01. Muscle

Marianne De Visser

Department Of Neurology, Academic Medical Centre, Amsterdam, NL

Abstract: Idiopathic inflammatory myopathies (IIMs) can be distinguished into subacute onset and treatable disorders (dermatomyositis (DM), necrotizing immune mediated myopathy (IMNM), antisynthetase syndrome (ASS), non-specific myositis (NSM)) and chronic inclusion body myositis (IBM). The mainstay of treatment in the treatable IIMs is long-term oral glucosteroids, and second line immunosuppressants are often added not only to obtain better efficacy but also for its steroid-sparing effect. If patients do not respond quickly to oral steroids one might consider intravenous administration of methylprednisolone or add third line medication such as rituximab (RTX) of intravenous immunoglobuline (IVIg). A trial with RTX on DM/PM did not reach the primary and secondary outcome measures. However, most of the patients clearly improved. IVIg was investigated in two RCT’s and various open-label prospective trials on refractory DM/PM patients and was found to be clinically efficacious. Still, long-term outcome in most IIM patients is not favourable. IIM patients have a polycyclic or chronic continuous course in almost 70% of the cases with similar percentages of perceived disabilities and lower quality of life scores after long-term follow up. This requires other vigorous treatment modalities, which not only aim at suppressing inflammation but also at preventing muscle damage. Increased knowledge about the pathomechanisms of IIMs will likely advance new and targeted treatments. Recent data suggests that exercise could be an effective anti-inflammatory treatment albeit the underlying mechanisms are not fully understood. IBM is as yet considered to be treatment-resistant. Not only is IBM refractory to the conventional immunosuppressive and immunomodulating modalities, but recently a phase 2b/3 study with bimagrumab, a monoclonal antibody that acts via the myostatin-mediated induction of muscle growth failed its primary endpoint. The results of a proof-of-concept study with rapamycine were promising. Conducting clinical trials in IIMs is challenging for many reasons. First, classification seems to be a moving target with the ever-increasing number of myositis-specific autoantibodies giving rise to further subclassification. Second, consensus on assessment tools that are highly responsive to interventions is required. The International Myositis Assessment and Clinical Studies Group ‘response criteria’ are recently published and could serve as such. Third, patient reported outcome measures are indispensible to evaluate the efficacy of a therapy and currently, they are under development.

SS 2.1 / #224TISSUE ENGINEERING STRATEGIES FOR REPAIR OF PERIPHERAL NERVE

Topic: 11. Nerve Regeneration

Anthony Windebank

Mayo Clinic, Rochester, US

Abstract not received.

SS 2.2 / #1019USE OF PHYSICAL METHODS IN NERVE REGENERATION

Topic: 11. Nerve Regeneration

Thomas Hausner

Trauma Surgery, Lorenz Böhler Trauma Hospital, Vienna, AT

Abstract: Regeneration and recovery of peripheral nerves after injury still today is a long-lasting procedure. Human nerves elongate with an average speed of 1 mm per day. Transection of a nerve at the level of the forearm e.g. with 25cm distance to the finger-tips would stand for about 250 days of recovery, given that rapid surgery has been performed corresponding to the actual technical standard. Increasing the speed of elongation would be very helpful in the post-surgical treatment. Electric stimulation since long time is used in nerve regeneration, with quite good results. However, new physical methods to increase axonal recovery are in development. Extracorporeal shock wave treatment (ESWT) is an established method in wound regeneration, bone regeneration and integration of skin grafts as well as treatment of some painful conditions as plantar fasciitis or humero-radial epicondylitis. In the last few years ESWT has been examined extensively in the field of nerve regeneration. Different in vivo and in vitro studies have been performed using the Dermagold 100 device (MTS, Germany). It could be clearly shown that axonal elongation is increased by a single use of ESWT immediately after surgery in different rat experimental nerve injury models. ESWT in vitro enhances stemness and preserves multipotency of adipose derived stem cells. ESWT in vitro also increases Schwann cell survival and activation state. ESWT may augment and potentiate the axonal elongation and functional recovery in a regenerating peripheral nerve segment. It also can be seen as a promising supporting tool for tissue engineering in peripheral nerve regeneration.

SS 2.3 / #378NEW DEVELOPMENTS IN CONDUITS

Topic: 11. Nerve Regeneration

David Hercher

Ludwig Boltzmann Institut, Vienna, AT

Abstract not received.

SS 3.1 / #70THE ROLE OF HU PROTEINS IN THE DEVELOPMENT OF PARANEOPLASTIC NEUROPATHIES

Topic: 08. Cancer

Bruno Giometto

Universita die Padova, Padova, IT

Abstract not received.

SS 3.2 / #79PHYSIOPATHOLOGY OF PARANEOPLASTIC GANGLIONOPATHIES

Topic: 08. Cancer

Romana Hoeftberger

Institute Of Neurology, Medical University of Vienna, Vienna, AT

Background: Paraneoplastic ganglionopathies are acquired neuronopathies that are characterized by a primary degeneration either of sensory neurons in dorsal root ganglia (paraneoplastic sensory neuronopathy, PSN) or sympathetic and parasympathetic neurons in autonomic ganglia (paraneoplastic autonomic neuronopathy, PAN). Methods: Summary of relevant findings in paraneoplastic ganglionopathies with emphasis on physiopathology and clinical presentation. Results: The PSN is mainly associated with small cell lung cancer and antibodies directed against intracellular antigens, so-called onconeuronal antibodies. These antibodies can be found in up to 80% of cases, most frequently anti-Hu or anti-CV2/CRMP5, less common amphiphysin antibodies. The pathogenetic concept is considered to be an immune response that is initially triggered by an aberrant expression of the onconeuronal antigen by tumor cells and subsequently misdirected against the nervous system. Neuropathological investigation reveales moderate inflammation with diffuse endoneurial T-cell, B-cell- and plasma cell infiltration in the spinal ganglia. CD8-positive T-cells are tightly attached to the surface of neurons indicating a T-cell mediated attack resulting in irreversible neuronal death. Nerve biopsy usually shows an axonal neuropathy with loss of large myelinated fibers and interstitial macrophages containing myelin debris. The clinical presentation is characterized by a subacute onset and rapidly progressive disease course with asymmetrical or multifocal numbness in the upper or lower limbs, severe impairment of joint position and vibratory sensation, pain, paresthesias, and sensory ataxia. Cranial nerve involvement may present as loss of taste, numbness of the face or sensorineural hypoacusia. PSN associated with anti-Hu antibodies often presents with additional CNS involvement such as encephalomyelitis but may remain an isolated syndrome in about 25% of cases. PSN associated with anti-CV2/CRMP5 antibodies more often presents as a mixed axonal and demyelinating neuropathy, predominates in the lower limbs, may have motor involvement, and pain is less frequent. PSN associated with amphiphysin antibodies may present with additional symptoms of stiff person syndrome or encephalopathy. Patients with PAN may either present as chronic intestinal pseudo-obstruction due to affection of the enteric plexus, or less common as subacute pandysautonomia with dysfunction of the sympathetic and parasympathetic nervous system. Patients may harbor anti-Hu antibodies, up to 20% may have ganglionic acetylcholine receptor antibodies. The underlying tumor in PSN and PAN often remains occult for a long time and search for a malignancy should focus in particular on the detection of a SCLC. Conclusion: Early diagnosis of paraneoplastic ganglionopathy by the detection of onconeuronal antibodies is important to confirm the diagnosis and initiate tumor screening. Early treatment of the cancer gives the best chance of stabilizing the disorder.

SS 3.3 / #133PARANEOPLASTIC MUSCLE DISORDERS

Topic: 08. Cancer

Andrew Mammen

NIAMS/NIH, Bethesda, US

Abstract not received.

SS 3.4 / #170LAMBERT-EATON-SYNDROME (LEMS)

Topic: 08. Cancer

Jan Verschuuren

Leiden University Medical Center, Leiden, NL

Abstract not received.

SS 4.1 / #159UPDATE ON CLINICAL ASPECTS OF GLYCOGEN STORAGE DISORDERS

Topic: 01. Muscle

Antonio Toscano

University of Messina, Messina, IT

Abstract not received.

SS 4.2 / #188NOVEL ENTITIES IN CONGENITAL MYOPATHIES OF ADULT ONSET

Topic: 01. Muscle

Baziel Van Engelen

Radboud University Medical Centre, Nijmegen, NL

Abstract not received.

SS 4.3 / #161NEW PHENOTYPES IN TITIN DEFECTS

Topic: 01. Muscle

Bjarne Udd

Tampere Neuromuscular Center, Tampere, FI

Abstract not received.

SS 5.1 / #1037STANDARDS OF CARE: WHAT WE HAVE LEARNED FROM LONG TERM-MANAGEMENT IN CHILDREN WITH NMD’S

Topic: 13. Pediatric

Guenther Bernert

Department Of Paediatrics, Kaiser Franz Joseph Hospital, Vienna, AT

Abstract not received.

SS 5.2 / #832FUTURE OF AAV-BASED GENE THERAPY APPROACHES FOR NMDS

Topic: 13. Pediatric

Thomas Voit

UCL Great Ormond Street Institute of Child Health, London, GB

Abstract: After more than a decade of animal experimentation, AAV-based clinical trials are now under way addressing Spinal Muscular Atrophy (SMA), Duchenne Muscular Dystrophy (DMD) and myotubular myopathy. They are addressing patients from infancy to young adults as well as different organ systems (CNS, skeletal and cardiac muscle). While too early to judge results across disease applications, there are important commonalities particularly regarding route of administration and maximum dosage in vector genomes/kg. At the same time, important questions remain, which need to be addressed in the future, both in animal experiments and in the human. These include the issues of hepatic and even potentially systemic toxicity of AAV capsids; pre-existing and treatment-induced immunity to AAV; the need for re-administration depending on the target tissue and the degree of genetic correction achieved. In some diseases such as SMA the route of administration remains an issue and has important consequences on the total dose, but potentially also on the biodistribution. In order to fine-tune these treatment approaches in the human biomarkers are becoming increasingly important to monitor the treatment effect over time. Finally, both in SMA and in DMD there is a potential to combine AAV-based gene therapy with chemical antisense-treatment, even if these technologies at the moment are largely developed in competition. These questions will be discussed in light of the most recent clinical and experimental data followed by a discussion of possible future steps.

SS 5.4 / #856TRANSITION FROM PEDIATRIC INTO ADULT CARE: A LONG WAY TO GO?

Topic: 13. Pediatric

Thomas Serjensen

Karolinska Institute, Solna, SE

Abstract not received.

SS 6.1 / #151GENERAL PRINCIPLES AND CLINICAL ASPECTS OF CIPN

Topic: 08. Cancer

Nathan Staff

Neurology, Mayo Clinic, Rochester, MN, US

Background: Chemotherapy-induced peripheral neuropathy (CIPN) is a common dose-limiting side effect that follows administration of several chemotherapeutic classes. While most CIPN is due to direct neurotoxicity of the chemotherapeutic, the recent introduction of check-point inhibitor cancer therapies has also resulted in a variety of immune-mediated neuromuscular side effects. CIPN occurs in up to 50% of all patients receiving neurotoxic chemotherapy and has been associated with both acute and long-term morbidities. Methods: Literature review was performed. Results: The clinical manifestations and pathomechanisms of CIPN from the different neurotoxic chemotherapy classes will be reviewed. The epidemiology and disease burden of CIPN will be explored by highlighting a recent study from Olmsted County, MN. Treatment and preventative strategies for CIPN, which have been largely unsuccessful, will also be described. Finally, a discussion surrounding the discovery and validation of CIPN susceptibility factors will be provided. Conclusion: CIPN continues to be a significant problem despite the development of more targeted cancer therapies. Key outstanding questions in CIPN are: 1) What are the pathomechanisms of CIPN? 2) Why is there variable susceptibility to CIPN? Answers to these key questions are expected to lead to rational predictive, preventative, and treatment strategies for this entity.

SS 6.2 / #196BASIC MECHANISMS: AXONAL DEGENERATION AND CHEMOTHERAPY-INDUCED PERIPHERAL NEUROPATHY

Topic: 08. Cancer

Ahmet Hoke

Johns Hopkins University School of Medicine, Baltimore, US

Abstract not received.

SS 6.3 / #51ANIMAL MODELS OF CHEMOTHERAPY-INDUCED PERIPHERAL NEUROPATHY

Topic: 08. Cancer

Guido Cavaletti

Head, Experimental Neurology Unit And Phd Program In Neuroscience School Of Medicine, University of Milano-Bicocca, Bicocca, IT

Abstract not received.

SS 7.1 / #157NEW GENES AND NEW MECHANISMS IN INHERITED NEUROPATHIES

Topic: 02. Neuropathy

Vincent Timmerman

Biomedical Sciences, University Of Antwerp, Antwerpen, BE

Background: New genes and new mechanisms in inherited neuropathies Vincent Timmerman Peripheral Neuropathy Research Group, University of Antwerp, Belgium Inherited peripheral neuropathies (IPN) are genetic conditions affecting 1 in 2,500 individuals. Charcot-Marie-Tooth (CMT) neuropathy is the best known form characterized by a vast phenotypic and genetic heterogeneity. The identification of mutations in more than 100 known genes through gene screening panels, whole exome or genome sequencing to find variants in novel disease causing genes, in combination with the increasing availability of cell and animal models, has deepened our understanding in the disease mechanism. The heterogeneity is complicated by the fact that CMT associated genes have diverse functions; they regulate myelination through Schwann cells, take care of axonal transport and neuronal metabolism, or have essential cellular functions by regulating autophagy and protein quality control. However, despite this knowledge there is still no effective therapy for most patients with CMT and related disorders. Methods: More recently novel models, such as the use of patient derived induced pluripotent stem cells, and neurons differentiated from these cells, in combination with omics approaches has opened novel opportunities for identifying common disease mechanisms and pathways. Results: These new methods will identify mode-of-actions and potential targets for therapy that are applicable for multiple CMT phenotypes. Conclusion: This information will complement IPN mutation databases, improve clinical and molecular diagnosis, and hopefully allow treatment strategies for some of these rare to ultra-rare IPN phenotypes.

SS 7.2 / #148THERAPEUTIC OPTIONS IN CMT

Topic: 02. Neuropathy

Michael Sereda

Neurogenetics, Max-Planck-Institute of Experimental Medicine, Gottingen, DE

Abstract not received.

SS 7.3 / #126FAMILIAL AMYLOID NEUROPATHIES: A TREATABLE GENETIC NEUROPATHY

Topic: 02. Neuropathy

Davide Pareyson

Dept Of Clinical Neurosciences, IRCCS Foundation, C.Besta Neurological Institute, Milan, IT

Abstract: Inherited transthyretin amyloidosis (ATTR) is an autosomal dominant disorder due to mutations of the transthyretin (TTR) gene. TTR is synthetized mainly by the liver and released in plasma as a tetrameric transport protein. Mutations in TTR, of which Val30Met is the most common worldwide, cause transthyretin tetramer dissociation, monomer misfolding, and aggregation into insoluble fibrillar proteins in different tissues. Orthotopic liver transplantation (OLT), by removing the main site of mutated TTR production, proved able to halt or slow neurological progression and was until few years ago the standard-of-care treatment in patients aged <50 years with Val30Met mutation. OLT is associated however with not negligible mortality rate and is not curative, since cardiac disease tends to progress and leptomeningeal amyloid deposition may become an issue. Tafamidis meglumine is a small molecule which kinetically stabilizes the TTR tetramer and prevents its dissociation into amyloidogenic monomers. It proved able to slow down disease progression particularly in the early disease phases and is currently approved in several countries for treatment of symptomatic patients with polyneuropathy in disease stage I (independent ambulation). Responders were also described among patients with late-onset disease, non-Val30Met mutations, and in later disease stages. The old nonsteroidal anti-inflammatory drug diflunisal has also been reported to be effective as a TTR tetramers stabilizer and produced significant slowing in disease progression in treated patients. The antibiotic doxycycline and the taurine conjugate form of ursodeoxycholic acid (TUDCA) have a synergistic effect on fibril disruption and their use is currently under investigation with encouraging results. Monoclonal antibodies directed against either the serum amyloid P component (SAP) or the amyloidogenic forms of transthyretin constitute another strategy to clear the amyloid deposits. Antisense Oligonucleotides (Inoserten) or interfering RNA lipid nanoparticles (Patisiran) binding to wild type and mutated TTR mRNA proved able to reduce TTR production by more than 75% and both proved very effective in two recently completed phase III trials. Both trials reached the primary endpoints and multiple measures were significantly better in treated as compared to untreated patients: stabilization or improvement occurred for a good proportion of treated patients. Inoserten was administered subcutaneously once a week for 15 months; thrombocytopenia and renal problems were adverse events which required monitoring of platelet and renal function. Patisiran, administered intravenously every 3 weeks for 18 months, was well tolerated with infusion-related reactions and peripheral edema as the most relevant reported side effects. Both treatments were effective independently from disease stage, presence of cardiopathy, type of mutation. The development of such novel therapies is changing the natural history of ATTR-neuropathy from a relentlessly progressive disorder inexorably leading to death into an effectively treatable disorder.

SS 8.1 / #1028CRANIAL NERVES: WITHIN AND OUT OF THE SKULL, INCL. ANGIOSOMA

Topic: 07. Cranial Nerves

Wolfgang Grisold¹, Anna Grisold², Stefan Meng³

¹Ludwig Boltzmann Institute for Experimental und Clinical Traumatology, Vienna, AT;²Dep. Neurology, Allgemeines Krankenhaus Vienna, Vienna, AT;³Institute for Radiology, KFJ hospital, Vienna, AT

Abstract: The course of cranial nerves (CN) is characterized by their intraparenchymal, intracranial part, the site of exit of the skull and their peripheral course. Thus dysfunction can be due to brainstem lesions, meningeal and CSF involvement, local changes at their exit of the skull, and a variety of conditions in their extracranial course. All parts of the cranial nerves are dependent on blood supply, which is provided by small arteries.The distribution of the blood supply follows the distribution of angiosomas, which follows a concept applicable for the whole body. According to this concept of blood supply, individual nerves receive the blood supply in different segments from adjacent angiosomas. As a practical consequence, intravascular interventions as embolizations of tumors of the base of the skull, can damage cranial nerves. As indirect signs of damage of motor nerves, also the MR visualization of muscles at the base of the skull is useful, which helps to detect asymmetries and neurogenic lesions. The tongue muscles as an example for strict unlilateral blood supply is a good example. Increasingly ultrasound can be used to demonstrate the extracranial parts of the nerves, where also thickening, and local tumors can be demonstrated.

SS 8.2 / #44INFECTIOUS AND INFLAMMATORY CRANIAL NERVE LESIONS

Topic: 07. Cranial Nerves

Nazha Birouk

Clinical Neurophysiology Rabat, Speciality Hospital, Rabat, MA

Abstract: Cranial nerves can be involved in various infectious and inflammatory diseases either as a mononeuropathy or multicranial neuropathy. The diagnosis can be easily made in conditions with other expressions of the infection or inflammations within the nervous system or in extra-neurologic organs with in some conditions typical presentations. The diagnosis might be more challenging when the cranial neuropathy is the revealing symptom. The most frequent infection worldwide remains an active infectious ganglioneuritis caused by varicella zoster virus, producing shingles. The commonly associated cranial nerve neuropathies are: herpes zoster ­ophthalmicus (10% to 20% of all zoster cases), the Ramsay Hunt syndrome (triad of ipsilateral facial paralysis, ear pain, and vesicles in the auditory canal and auricle) and optic neuritis. Facial nerve palsy can be due to Lyme borreliosis with a similar clinical presentation to Bell’s palsy. This infection is to be searched in endemic areas, in the presence of skin rash or if the facial palsy is bilateral and/or recurrent. Cranial neuropathies in HIV occur at various stages of infection and are sometimes multifocal. Facial nerve palsy, for example, can develop at the time of seroconversion or later in the disease course secondary to opportunistic infections. In immunocompetent patients, many infectious conditions can be accompanied by cranial neuropathies such as meningitis due to tuberculosis, syphilis, listeriosis, cryptococcus and various other infectious agents. Cranial nerves might be impaired by contiguous infection as otitis or sinusitis. Cranial neuropathy can be associated to systemic inflammatory disorders such as sarcoidosis (mostly nerves VII, VIII and II), Sjogren syndrome (mostly nerves V and II) or ANCA vasculatis (nerves III, IV, VI, VII and X) and others. IgG4-related disease has been newly identified with a wide spectrum of diseases that can involve nearly any organ system, including the central and peripheral nervous systems. The principal neurological manifestations result from orbital disease, pachymeningitis, and pituitary gland and stalk involvement. The common aspect is an inflammatory pseudotumor with possible impairment of oculomotor (as Tolosa Hunt syndrome), trigeminal and optic nerves. The diagnosis is based on the serum IgG4 elevation, the histological aspects with significant infiltration with IgG4 positive plasma cells, and the elimination of other inflammatory disorders like vasculitis. The disease responds well to treatment by corticosteroids. Specific inflammatory diseases of central nervous system such as multiple sclerosis and NMO imply cranial neuropathies, mostly optic neuritis but also other nerves such as oculomotor, facial and trigeminal nerves. We should keep in mind that an authentic Guillain Barre syndrome can rarely present with isolated bilateral facial nerve or multicranial nerves palsy.

SS 8.3 / #230PAINFUL CRANIAL NERVE LESIONS

Topic: 07. Cranial Nerves

Frank Thömke

Klinikum Worms gGmbH Fachbereich Neurologie, Worms, DE

Background: This presentation deals with cranial nerve palsies with persistent pain lasting days to weeks. Methods: Description of clinical signs, diagnosis and therapy. Results: Optic neuritis may be accompanied by persistent pain on the affected side, which occurs or increases with movements of the affected eye. Pain usually decreases with high does steroid treatment (usually 1000 mg methylprednisolone for 3 days). MRI should be done since optic neuritis is a frequent initial symptom of multiple sclerosis. Moreoever, one should look for aquaporin-4 antibodies (NMO-IgG) to detect the beginning of a neuromyelitis optica. Painful ocular motor nerve lesions are often summarized as ”painful ophthalmoplegia, a heterogenous group of diseases characterized by paresis of one or more ocular motor nerves associated with frontal or orbital pain. Vascular, inflammatory or tumorous diseases are main causes. Up to one third of ocular motor nerve palsies are attributed to microvascular nerve infarctions, a diagnosis by exclusion. Most of the patients complain ipsilateral pain, especially with 3^rd nerve palsies. This must be differentiated from 3^rd nerve palsies due to an aneurysm, which is easily done by MRI- or CT-angiography. Diagnosis of a Tolosa Hunt syndrome depends, among others, on the demonstration of granulomatous inflammation of the cavernous sinus, the superior orbital fissure or the orbit demonstrated by MRI or biopsy. Pain promptly resolves with steroid treatment (usually 1 mg prednisolone or methylprednisolone per kg body weight). Abnormal eye movements recover within several weeks, which seem to be equally probable with or without steroids. Diagnosis of recurrent painful ophthalmoplegic neuropathy (“ophthalmoplegic migraine”) may be considered after two attacks and exclusion of an orbital, parasellar or posterior fossa tumor. In some patients, MRI may disclose gadolinium-enhancement of a thickened 3^rd nerve. Pain promptly decreases with steroid treatment (usually 1 mg prednisolone or methylprednisolone per kg body weight). Abnormal eye movements recover within several weeks, which seem to be equally probable with or without steroids. Persistent pain with trigeminal nerve lesions may occur with acute or previous Herpes zoster, previous trauma, multiple sclerosis, or space occupying lesions. Herpes zoster may be diagnosed by laboratory findings, otherases by MRI or (CT). Herpes Zoster is treated with aciclovir or valaciclovir, and persistent pain due to multiple sclerosis with high dose steroids (usually 1 000 mg methylprednisolone for 3 to 5 days). Pain is a prominent symptom in facial palsy due to Herpes Zoster (Ramsay Hunt syndrome) and treated with aciclovir or valaciclovir (and steroids) added by analgetics and/or anticonvulsant substances such as carbamazepine or pregabalin. Bell’s palsy may also be associated with retroauricular pain, which resolves with steroid treatment of Bell’s palsy. Painful lesions of one or multiple of these nerves may occur with space occupying lesions or meningeosis neoplastica. They are often associated with diffuse headache and focal signs like hemiparesis or hemiataxia. Treatment depends on the etiology and involves neurosurgical procedures, steroid and radiation. Conclusion: MRI (or CT) should be done in most patients with painful cranial nerve lesions, and MRI- or CT-angiography in some of them. Steroids are an effective treatment in most cases.

SS 8.4 / #190PAROXYSMAL DYSFUNCTIONS

Topic: 07. Cranial Nerves

Friedrich Zimprich

Department Of Neurology, Medical University of Vienna, Vienna, AT

Abstract: Neuromuscular specialists are often required to evaluate patients displaying symptoms of transient (upper) cranial nerve dysfunctions, with ocular myasthenia gravis being a main differential diagnosis. In fact there is a wide range of different diseases which might manifest as oculomotor dysfunction with or without ptosis either as a consequence of cranial nerve palsies (III, IV or VI) or because they mimic these conditions. While many of these disorders may eventually result in a typical, i.e. clearly recognizable clinical picture the presentation in the initial stages or in mild cases can take the shape of fluctuating or paroxysmal, transient symptoms, which obviously stands in the way of finding a fast and definite diagnosis. The possible differential diagnoses range from ocular myasthenia to other myopathies (e.g. mitochondrial disorders), autoimmune diseases (e.g. thyroid-associated ophthalmopathy), inflammatory neuropathies, diseases affecting the intracranial pressure (intracranial hypotension or pseudotumor cerebri), vascular ischaemic diseases, diabetes associated cranial nerve palsies, inflammatory lesions of the central nervous system, nerve sheath tumors or other space occupying lesions along the nerves to ocular neuromyotonia. This differential diagnoses will be discussed and illustrative cases will be presented.

SS 9.1 / #1013PROTEINOPATHIES (THE AUTONOMIC VIEW)

Topic: 05. Autonomic

G Wenning

Department Of Neurology, Medical University Innsbruck, Innsbruck, AT

Abstract not received.

SS 9.2 / #1014PROTEINOPATHIES (THE NEUROMUSCULAR VIEW)

Topic: 05. Autonomic

Walter Struhal

Department For Neurology, University Clinic Tulln, Karl Landsteiner University of Health Sciences, Tulln, AT

Abstract not received.

SS 9.3 / #1015HEREDITARY NEUROPATHIES (THE AUTONOMIC VIEW)

Topic: 05. Autonomic

Max J. Hilz

Neurology, Universitätsklinikum Erlangen, Erlangen, DE

Abstract not received.

SS 9.4 / #1016HEREDITARY NEUROPATHIES (THE NEUROMUSCULAR VIEW)

Topic: 05. Autonomic

Michaela Auer-Grumbach

Department Of Orthopaedics, Medical University of Vienna, Vienna, AT

Abstract not received.

SS 9.5 / #1017METABOLIC ANS DISEASE (DIABETES AND LIVER) (THE AUTONOMIC VIEW)

Topic: 05. Autonomic

R Freeman

Beth Israel Deaconess Medical Center, Boston, US

Abstract not received.

SS 9.6 / #1039METABOLIC ANS DISEASE (DIABETES AND LIVER) (THE NEUROMUSCULAR VIEW)

Topic: 05. Autonomic

Paola Sandroni

Mayo Clinic, Rochester, US

Abstract not received.

SS 10.1 / #462017 ADA POSITION STATEMENT ON DIABETIC NEUROPATHY: DOES IT CHANGE YOUR PRACTICE?

Topic: 02. Neuropathy

Vera Bril

Department Of Medicine (neurology), University Health Network, University of Toronto, Toronto, CA

Abstract not received.

SS 10.2 / #144SCIENTIFIC DISCOVERY LEADS TO CLINICAL TRIALS IN DIABETIC NEUROPATHY

Topic: 02. Neuropathy

James Russell

University of Maryland School of Medicine, Baltimore, US

Abstract: A complex constellation of pathways are directly or indirectly affected in diabetic neuropathy. Dissecting out these pathways can lead to development of new approaches to reverse neuropathy and treat neuropathic pain. Despite the focus on glycemic control in diabetes, the evidence from randomized clinical trials that improved glycemic control reduces the prevalence of neuropathy in the majority of diabetics is unclear. The evidence for type I diabetes is strong but weak or absent for type 2 diabetes mellitus. While many potential pathways have been recognized as potential targets for therapy, this lecture will focus on mechanisms that currently offer or may offer immediate translation into clinical practice. While many clinical trials in diabetic neuropathy have failed, increasingly trials are being initiated by investigators that understand the complexities of mechanism and trial design. They appreciate the importance of sensitive and rapidly responsive efficacy measures in mild neuropathy observed early in the course of diabetes, when response to therapy is most likely to occur. There is considerable interest in the role of lifestyle interventions in reversing diabetic neuropathy. However, what is not always appreciated is that the dietary and exercise manipulations have clear and measureable effects on specific ­biological pathways similar to the effect of a medication. These interventions affect critical signaling pathways that regulate mitochondrial function, generation of reactive oxygen species, lipid metabolism, and growth factor production that may lead to nerve regeneration. Lipidomic characterization may lead to not only understanding how lipid pathways are implicated in diabetic neuropathy (pathway characterization) but also how manipulation of abnormal lipid metabolism may lead to therapy. Already, there is evidence that modification of lipid metabolism can result in improvement in diabetic small fiber neuropathy in humans. A novel approach to therapy has resulted from the observation that muscarinic receptor antagonists are implicated in protection from axonal degeneration both in vitro and in vivo. Neurite outgrowth from sensory neurons is in part mediated by muscarinic receptor-dependent regulation of mitochondrial function through the AMPK signaling pathway. Consistent with these observations in vitro, pharmacological blockade of the muscarinic receptor, M1R, using specific or selective antagonists, prevented or reversed peripheral neuropathy and reduced diabetes-induced mitochondrial dysfunction in vitro and in vivo. Work in vivo is currently being translated into clinical trials. Finally, the implications of specific drugs that target the Peroxisome proliferator-activated receptor-gamma co-activator 1alpha (PGC-1alpha) signaling pathway, which critically regulates mitochondrial and lipid metabolism, and the potential for translation to clinical trials will be discussed. Common polymorphisms of PGC-1alpha are associated with conversion from impaired glucose tolerance to diabetes and loss of PGC-1alpha causes neuropathy that is worsened by diabetes. Thus, understanding the critical mechanisms that lead to diabetic neuropathy may result in improved therapy and management of neuropathic symptoms.

SS 10.3 / #68PAINFUL DIABETIC NEUROPATHY: A MANAGEMENT CENTERED APPROACH

Topic: 02. Neuropathy

Eva Feldman

University of Michigan, Ann Arbor, US

Abstract: Pain is a persistent and morbid complication of diabetic polyneuropathy (DPN). There are no compelling data supporting the concept that glycemic control alone improves DPN pain, and most physicians and patients turn toward pharmacologic treatment. The American Diabetes Association, the American Academy of Neurology and the Canadian Pain Society are among the organizations that have issued pain management guidelines for DPN. DPN is controlled by different classes of agents: monoamine reuptake inhibitors and anticonvulsants are the main stay of therapy. Two agents, duloxetine (a selective norepinephrine and serotonin reuptake inhibitor) and pregabalin (a calcium channel a2-δ subunit ligand anticonvulsant) are approved by the FDA, Health Canada and the European Medicines Agency for painful DPN treatment. Other effective monoamine reuptake inhibitors, not officially approved, include the tricyclic antidepressant amitriptyline, the secondary amines, nortriptyline and desipramine and the dual reuptake inhibitor venlafaxine. Among the effective anticonvulsants that lack formal agency approval, gabapentin (another ligand of the calcium channel a2-δ subunit) is most commonly used, followed by topiramate and less commonly carbamazepine or phenytoin. Following guidelines, either duloxetine or pregabalin are used in the initial treatment of painful DPN; if neither single agent provides pain relief, the drugs are taken together, depending on side effect profiles. A common final dosage of duloxetine is either 60 or 120 mg/day, depending on tolerability; pregabalin is 150 mg, either twice or thrice daily, again dependent on tolerability. When drug cost is an issue, an alternative to the above approach is to begin with gabapentin, reaching doses up to 1,800 mg to 3,600 mg/day in 3 to 4 divided doses. The tertiary amine amitriptyline can be added to gabapentin, or also begun as sole therapy, at nightly doses that range from 50 up to 100 mg. The secondary amines, nortriptyline and desipramine, are preferred over amitriptyline, if there is any history of cardiovascular disease or risk of urinary retention due to prostatism. While providing less pain relief that amitriptyline, the secondary amines have a more robust safety profile; finally, the dual reuptake inhibitor venlafaxine, also provides pain relief, although studies suggest pain reduction is less that with duloxetine. Dosages of 150 to 225 mg/day can be used alone or in combination with an anticonvulsant drug. Importantly, duloxetine or venlafaxine therapy is best combined with anticonvulsant therapy; combination with the tricyclic antidepressants should be used only with caution secondary to adverse patient outcomes. Tapentadol is a centrally ­acting opioid with a dual mechanism of action: inhibition of noradrenaline reuptake and activation of the μ-opioid receptor. While tapentadol is FDA approved, the International Association for the Study of Pain’s Special Interest Group on Neuropathic Pain (NeuPSIG) completed a systematic meta-analysis and determined that the efficacy of tapentadol in the treatment of painful DPN was uncertain. The use of tapentadol is therefore not recommended as a first or second line treatment, and opioids as a class of drugs should be avoided in the treatment of painful DPN.

SS 11.1 / #851JAMES LIND ALLIANCE PRIORITY SETTING PARTNERSHIP IN NEURO-ONCOLOGY (RESEARCH PRIORITIES)

Topic: 12. Patient Issues

Kathy R. Oliver

International Brain Tumour Alliance (IBTA), Tadworth, GB

Background: It is crucial that what patients value is reflected in research relating to treatment, care and support. This is particularly relevant in rare cancers, like brain and spinal cord tumours, where many clinical questions about these diseases remain unanswered. The James Lind Alliance (JLA - http://www.lindalliance.org/) was established in 2004 and is coordinated by the UK National Institute for Health Research (NIHR). It brings patients, caregivers and clinicians together in a ‘Priority Setting Partnership’ (PSP) to determine the top ten unanswered questions relating to a particular disease. Methods: The JLA PSP in neuro oncology (N-O) identified clinical research questions that were most important to people living with a brain or spinal cord tumour. The project’s scope was: clinical uncertainties of interventions for primary brain or spinal cord tumours, in people of any age, from diagnosis to terminal stages. The methods for determining the top ten uncertainties were: 1. identification of stakeholder representatives (28) from a cross-section of the brain tumour community; 2. obtaining funding from four brain tumour charities, Cochrane Neuro-Oncology, and Edinburgh and Lothian Health Foundation; 3. developing and producing a protocol and website (www.neuro-oncology.org.uk); 4. publicising the JLA PSP N-O survey to UK brain tumour communities and those abroad using multi-disciplinary professional and charity databases; 5. analysing first round survey results and eliminating duplicate questions and those already answered by previous research; 6. categorising and standardising questions into PICO (participants, interventions, comparisons, outcomes) format; 7. carrying out systematic Cochrane-style literature searches to ensure genuine uncertainties; 8. prioritising questions using standard JLA PSP methodology and unbiased facilitators; 9. conducting a second public survey on a short-list of prioritised questions; 10. holding a workshop to determine the final top ten questions using a modified Delphi and Nominal Group technique. Results: Over 600 individual questions were generated from the initial survey, a patient forum and the Database of Treatment Uncertainties (DUETS). A second public survey was distributed (44 PICO questions created from uncertainties resulting from the initial survey). Over 200 people responded and voted for their top ten research priorities for brain and CNS tumours. The final top ten uncertainties were agreed. Much of the work of the JLA PSP N-O evolved to form a core activity of the UK National Cancer Research Institute (NCRI) Brain and CNS Clinical Studies Subgroup on Supportive and Palliative Care, which is approaching UK governmental, neuroscience and charity funders to support research into the top ten uncertainties identified. Conclusion: The JLA PSP N-O collaboration was an enlightening and successful project. It will now be crucial to pro-actively promote the top ten research uncertainties for brain and CNS tumours in order to focus attention on what really matters to people affected by these diseases. It is vital to obtain reliable, evidenced-based information about these uncertainties through robust research focussed on the JLA PSP N-O top ten priorities.

SS 11.2 / #212HOW TO DO INVESTIGATOR-INITIATED TRIALS: PCORI

Topic: 12. Patient Issues

Richard J. Barohn

Neurology, University of Kansas Medical Center, Kansas City, KS, US

Abstract: In recent years there has been a great effort to get patients, families, community and patient advisory groups more involved in the clinical ­research process. When developing an idea for a clinical research project we get patients involved to identify their needs and what areas they believe we should focus on. We then place patients on the project steering committees, communication committees and Data Safety Monitoring Boards (DSMB). Outcome measures are increasingly becoming patient driven and the field of patient reported outcomes measures (PROM) is extremely important. We use various patient reported outcomes as either primary or secondary outcomes. In the USA such research is funded by the Patient Center for Outcomes Research Institute (PCORI). One such funding mechanism through PCORI is for comparative effectiveness research (CER). The goal is to compare the effectiveness of two or more interventions or approaches to health care by answering questions important to patients and other stakeholders. We have been successful in obtaining one of these awards to conduct a comparative effectiveness study of drugs for management of pain in cryptogenic sensory polyneuropathy (CSPN) called Patient Assisted Intervention for Neuropathy: Comparison of Treatment in Real Life Situations (PAIN CONTRoLS). We are comparing four medications (nortriptyline, duloxetine, pregabalin, mexiletine) at 45 sites in the USA and Canada. We enrolled 402 patients. The study assessed both effectiveness in reducing pain and quits due to various factors and utilized a novel Bayesian adaptive design. The results showed nortriptyline and duloxetine were more likely to have pain relief and fewer quits than pregabalin and mexiletine. We utilized patients and their caregivers in developing the concept and preparing the grant application. PCORI created an award that provides infrastructure in which the PCORI grants can operate through. This infrastructure called (PCORnet, the National Patient-Centered Clinical Research Network) goal is to foster a wide range of experimental and observational patient-centered studies. This network is broken down to Clinical Data Research Networks (CDRNs). University of Kansas Medical Center has a CDRN called the Greater Plains Collaborative (GPC). One of the first accomplishments by the GPC was to deploy the development of the Healthcare Enterprise Repository for Ontological Narration (HERON) system at KUMC. This is an i2B2 software program that allows use of electronic medical records to survey for potential research subjects. One of the first projects was to develop a survey and utilizing the sites EMR, identify patients and utilize this list to send out the survey. We took an existing functional status form (the Amyotrophic Lateral Sclerosis Functional Rating Scale- Revised (ALSFRS-R)) and asked patients what they wanted to change or what additional questions they wanted to see poised to them regarding their functional status. We then modified the form and then submitted a protocol to be able to send out this survey.

SS 11.3 / #213THE PATIENT VOICE IN MYASTHENIA GRAVIS TRIALS- PCORI, CER, AND MORE ALPHABET SOUP

Topic: 12. Patient Issues

Pushpa Narayanaswami

Neurology, Beth Israel Deaconess Medical Center/Harvard Medical School, Boston, MA, US

Background: The Patient Centered Outcomes Research Institute (PCORI) is a nonprofit, nongovernmental organization in Washington, DC, that funds patient-centered comparative effectiveness research (CER). CER is the generation and synthesis of evidence that compares the benefits and harms of two or more interventions or approaches to manage a condition or improve healthcare. The US Food and Drug Administration defines patient reported outcomes (PROs) as ”any report of the status of a patient’s health condition that comes directly from the patient, without interpretation by a clinician or anyone else”. PROs assess outcomes that are important to patients; they cannot be developed without actively engaging patients with the condition of interest. PROMISE-MG is a PCORI funded prospective, observational, comparative effectiveness trial of immunosuppressant treatments for myasthenia gravis (MG). We describe our patient engagement process to select a patient centered primary outcome measure. Methods: Patients were actively engaged to identify a PRO by 1. Questionnaire survey of 58 people with self-identified MG at the annual Myasthenia Gravis Foundation of America meeting. 2. An online, web-based focus group of 13 people with MG, using the results of the survey to develop the focus group script. 3. Selection of the outcome measure. 4. Evaluation of the measure in 30 patients with MG for completeness and accuracy in describing their experience with MG. Results: 1: Patient survey: Staying out of hospital was very important to 96% of respondents, followed by living independently (91.5%). Ability to ambulate normally, drive, groom themselves and normal speech, chewing and swallowing were very important to >80% of respondents. Fewer/less frequent side effects, fewer tablets/ less frequent dosing, less frequent physician visits/ laboratory monitoring were very important to over a third of respondents. Symptoms with the most significant impact were limb weakness (64%), bulbar and ocular symptoms (36-38%). The most burdensome adverse effects of treatment were weight gain (43%), mood swings (36%), insomnia (34%) and diarrhea (30%). 2. Focus group: the word ”fatigue” was most frequently associated with MG, followed by ”weakness” and ”double vision”. Participants endorsed frustration and isolation. Mobility limitations, visual symptoms and respiratory symptoms were most troublesome. Avoiding hospitalization was a high priority. The most concerning adverse effects were weight gain and long term risk of cancer. A good outcome was defined as ”fewer medication side effects and 80% improvement in symptoms”. 3: Based on the survey and focus group results, the MG-Quality of Life 15r scale (MG-QOL15r) was thought to capture outcomes of greatest importance to patients. 4. 29/30 patients to whom the MG-QOL15r was administered responded that it completely and accurately described their experience with MG. Conclusion: MG-QOL is a 60 item scale which was developed with input from patients. The MGQOL-15 was subsequently developed with rigorous psychometric methods. Rasch analysis resulted in the MG-QOL15r, a three option modification, recently validated in a large cohort. We confirmed that the MG-QOL15r accurately and completely reflects the patient voice and selected it as the primary PRO for PROMISE-MG. Acknowledgements: Donald Sanders, MD, Co-Primary Investigator, PROMISE-MG; Myasthenia Gravis Foundation of America

SS 11.4 / #308HOW CAN OUTCOMES OF CLINICAL STUDIES BE TRANSLATED FOR PATIENTS

Topic: 12. Patient Issues

Angela Genge

Montreal Neurological Institute and Hospital, Montreal, CA

Abstract not received.

SS 12.1 / #127PATHOPHYSIOLOGY OF THE NODE OF RANVIER

Topic: 02. Neuropathy

Antonino Uncini

Neuroscience, Imaging And Clinical Sciences, University “G. d’Annunzio”, Chieti-Pecsra, Chieti, IT

Background: The myelinated axons are organised in distinct domains characterised by specific molecular arrangements: nodes of Ranvier, paranodes, juxtaparanodes and internodes. The nodal region is a crucial evolutionary structure of the nervous system ensuring, by saltatory conduction, a fast transmission of impulses with the least expenditure of energy. It took almost eight decades, since the original description by Ranvier in 1871, to demonstrate that the nodes are the places where ionic currents generated action potentials for saltatory conduction, and only in the last two decades, the nodal region has been recognised as a possible site of specific autoimmune attack in peripheral neuropathies. For these neuropathies, the classification in demyelinating and axonal may be inadequate or even misleading, and the new category of nodo-paranodopathy has been recently proposed. Methods: In this lecture the process of saltatory conduction in myelinated and demyelinated axons will be firstly reviewed. Then the findings from serial electrophysiological studies, immunopathologic and ultrastructural evidence in humans, experimental models of autoimmune attack at the nodal region by antibodies against gangliosides, neurofascin 186, axoglial proteins (neurofascin 155, contactin 1, and contactin associated protein 1) will be examined. Results: The electrophysiological correlates of autoimmune attack at the excitable nodal axolemma and adhesion molecules at nodal and paranodal region ranging by a continuum from transitory nerve conduction failure to axonal degeneration, and the ”demyelinating” features, explainable just by the paranodal involvement, will be discussed. Conclusion: At last the utility of the autoimmune nodo-paranodopathy category will be re-emphasized as the term pointing to the site of nerve injury, reminds specific pathophysiological mechanisms, reconciles apparently contrasting electrophysiological and pathological findings, and avoids misdiagnosis and taxonomic confusion.

SS 12.2 / #172NEW PATHOGENETIC MECHANISMS UNDERLYING IMMUNE NEUROPATHIES

Topic: 02. Neuropathy

Hugh J. Willison

Institute Of Infection, Immunity And Inflammation, University of Glasgow, Glasgow, GB

Background: Guillain-Barré syndrome (GBS) is in part mediated by anti-GM1 ganglioside antibodies induced by preceding infections. Anti-GM1 antibodies target plasma membrane GM1 that is extensively distributed in both glial and axonal membranes, particularly at the node of Ranvier. Antibodies deposited at this site in models of GBS are associated with complement deposition, conduction block, structural disruption of ion channels and macrophage infiltration. The wide distribution of the GM1 ganglioside target leads to unwanted complexity in ascribing pathological outcomes to injury of cell-specific membranes, in particular unravelling the consequence of paranodal Schwann cell membrane injury on axonal function, and vice versa. Methods: To overcome this impasse, we have generated transgenic mice through glycosyltransferase manipulation that express GM1 exclusively in either neurons or glia, thus allowing us to very specifically target and injure axonal or glial membranes with a single anti-GM1 ganglioside antibody. Through this route we can create mouse models of both the axonal and demyelinating forms of GBS, induced by a single anti-GM1 antibody, thus creating otherwise highly comparable conditions. Results: Here, we show ­anti-GM1 antibody binding is restricted to the nodal axolemma in GalNAcT^-/--Tg(neuronal) mice and conversely to paranodal loops in GalNAcT^-/--Tg(glial) mice. When anti-GM1 antibody and a source of complement is added to a nerve-muscle ex vivo injury paradigm, there is a loss of axonal integrity (i.e. loss of neurofilament immunolabeling) when the neuronal membrane is targeted in GalNAcT^-/--Tg(neuronal). Conversely, axonal integrity is maintained when the paranodal membranes are decorated by antibody and complemnt products ex vivo in GalNAcT^-/--Tg(glial) mice. In an passive immunisation model in vivo, GalNAcT^-/--Tg(neuronal) mice acutely develop weakness, respiratory dysfunction, associated complement deposition, and degenerative pathology in distal axons. In contrast, GalNAcT^-/--Tg(glial) mice have significantly fewer abnormalities under the same acute conditions. Conclusion: These data indicate the high vulnerability of axonal membranes to acute injury and underline the importance of developing specific axonal projection strategies. In summary, targeting the nodal axolemmal or glial membranes allows us to study associated nodal pathology, and determine the downstream consequences on function and axon fate, currently a major area in GBS clinical research.

SS 12.3 / #137ANTIBODIES TO THE NODE OF RANVIER IN CIDP: A NEW CLUE TO THERAPY

Topic: 02. Neuropathy

Luis Querol

Neuromuscular Diseases Unit, Hospital de la Santa Creu i Sant Pau, Barcelona, ES

Abstract not received.

SS 13.1 / #216OVERVIEW – DRUG TREATMENT FOR SMA

Topic: 03. Motor Neurone

Janbernd Kirschner

Dept. Of Neuropediatrics And Muscle Disorders, Medical Center - University of Freiburg, Freiburg, DE

Background: Spinal muscular atrophy (SMA) is an autosomal-recessive, neuromuscular disorder that is characterized by degeneration of the anterior horn cells of the spinal cord, resulting in muscle atrophy and proximal muscle weakness. SMA is caused by a homozygous deletion in the survival motor neuron 1 (SMN1) gene on chromosome 5q13. The SMN gene region also comprises a centromeric copy containing the SMN2 gene. The severity of the disease correlates with age of onset and SMN2 copy number and varies from a severe muscle weakness with tetraplegia in infants to a mild proximal muscle weakness in ambulant children and adults. Affected patients need a multidisciplinary treatment approach to address the different manifestation of the disease. In addition to symptomatic treatment including nutrition and ventilatory suuport new pharmaceutical approaches have been developed to address different aspects of the pathophysiology. Methods: Targets of the most advanced approaches include survival of motor neurons, increase of SMN protein production from the SMN2 gene by splicing modifiers, and introduction of the missing SMN1 gene with viral vectors. Results: Currently, nusinersen is the only drug that has been approved for the treatment of SMA. It is an antisense oligonucleotide that is administered by intrathecal injections and modifies the splicing of the SMN2 gene. Phase III trials have shown shown clear improvement of motor function in infants with SMA type 1 and in young children with SMA type 2. Long term safety and treatment effect in adolescent and adult still need further evaluation. Other splicing modifiers have been indentified through screening methods, they can be administered orally and are currently evaluated in clinical trials. A gene therapy approach using a AAV9 virus with the SMN1 gene has shown promising results in a phase I study and a larger European phase III trial for SMA tpye 1 will start this year. Olesoxime is a drug that has been developed to improve survival of motor neurons, but results of an international placebo-controlled trial were not sufficient for approval. Additional explorations of the pharmacokinetics and its effect on functional outcomes are ongoing. Conclusion: Clinical trials show promising results for the treatment of SMA with splicing modifiers and gene therapy. Early initiation of treatment seems particularly effective and warrants the implementation of newborn screening programs. As SMA is a rare disease with a broad spectrum of severity clinical trials cannot cover all age groups and all stages of the disease. Patient registries are an important tool to collect additional information to document the long-term effect of any drug treatment in SMA.

SS 13.2 / #98TREATMENTS TO IMPROVE SURVIVAL OF MOTOR NEURONS

Topic: 03. Motor Neurone

Albert Ludolph

Universitätsklinikum Ulm, Ulm, DE

Abstract not received.

SS 13.3 / #73SPLICING MODIFICATION FOR SMA

Topic: 03. Motor Neurone

Nathalie Goemans

Treat-NMD Neuromuscular Network, Leuven, BE

Abstract not received.

SS 13.4 / #48GENE THERAPY FOR SMA

Topic: 03. Motor Neurone

Arthur H.m. Burghes¹, Jerry Mendell², Samiah Al-Zaidy², Richard Shell³, W. D. Arnold⁴, Louise Rodino-Klapac², Thomas W. Prior⁵, Linda Lowes², Lindsay Alfano³, Kathleen Church³, John T. Kissel⁴, Sukumar Nagendran⁶, James L’Italien⁶, Douglas M. Sproule⁶, Courtney Wells⁶, Kevin Foust⁶, Kathrin Meyer², Shibi Likhite², Vicki Mcgovern¹, Stephen Kolb⁴, Brian Kaspar⁶

¹Biological Chemistry And Pharmacology, The Ohio State University, Columbus, OH, US;²Center For Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, US;³Department Of Pediatrics, Nationwide Children’s Hospital, Columbus, OH, US;⁴Department Of Neurology, The Ohio State University, Columbus, OH, US;⁵Department Of Pathology, The Ohio State University, Columbus, OH, US;⁶AveXis, Inc., Bannockburn, IL, US

Abstract: Spinal Muscular Atrophy (SMA) is an autosomal recessive disorder caused by mutation or loss of the survival motor neuron 1 gene (SMN1) gene and retention of SMN2. The SMN2 gene produces insufficient SMN but increased copy number of SMN2 modulates phenotype and does result in immune tolerance to an immune response against SMN when it is introduced from exogenous sources. Spinal muscular atrophy has been modeled in both mice and pigs. Untreated SMA mice live for 14 days and show loss of motor neurons including electrophysiological defects of the neuromuscular junction and compound muscle action abnormalities (CMAP) and MUNE. Knockdown of SMN in pig results in similar motor neuron abnormalities. scAAV9 has the ability to cross the blood brain barrier and efficiently transduce motor neurons with either delivery through the blood stream or via CSF delivery. Early scAAV9-SMN treatment of SMA mice and pigs results in correction of survival and motor neuron defects including CMAP and MUNE. Latter introduction especially in the pig results in correction of CMAP but MUNE is reduced indicating that motor neurons once lost cannot be recovered but those remaining can compensate by sprouting. A phase 1 gene therapy trial of scAAV9-SMN (AVXS-101) was initiated in Type 1 SMA, the most severe form of SMA , with untreated children never gaining the ability to sit or maintain head control. All patients lacked SMN1 and had 2 copies of SMN2 and none contained the C859G variant which increases incorporation of SMN2 exon 7. Patients received an intravenous dose of AVXS-101 at the low dose (Cohort 1, n=3) or proposed therapeutic dose (Cohort 2, n=12). AVXS-101 had a favorable safety profile and improved survival when compared to natural history studies. All 15 patients were alive and event-free at 20 months of age and did not require permanent mechanical ventilation, compared with 8% in published natural history. Patients in Cohort 2 demonstrated improvements in motor function: 11/12 had achieved CHOP-INTEND scores >40 points and a mean increase of 24.6 points from a mean baseline of 28.2 points; 11/12 were able to sit unassisted for at least 5 seconds, 10 for at least 10 seconds, and 9 for at least 30 seconds; 11/12 achieved head control and 9 could roll over. Two patients were able to crawl, pull to stand, stand independently, and walk independently. None of the aforementioned motor function gains and milestone achievement is seen in untreated patients with SMA type 1 and 2 copies of SMN2. Asymptomatic elevated serum aminotransferase levels occurred in 4 patients and was attenuated by prednisolone treatment. (see Mendell et al this meeting for further details.) As in preclinical studies in animal models scAAV9-SMN (AVXS-101) has a dramatic impact on motor function and appeared to increase survival. This was particularly evident with early treatment in cohort 2 with achievement of motor milestones rarely or never seen in the type 1 SMA population.

SS 14.1 / #90MR NEUROGRAPHY: NEW APPROACHES AND TECHNIQUES FOR DIAGNOSING MONONEUROPATHIES

Topic: 06. Mononeuropathy

Jennifer Kollmer

Heidelberg University Hospital, Heidelberg, DE

Abstract not received.

SS 14.2 / #189NEW ULTRASENSITIVE ULTRASOUND METHODS

Topic: 06. Mononeuropathy

Stefan Meng

KFJ Hospital, Vienna, AT

Abstract not received.

SS 14.3 / #63OCT

Topic: 06. Mononeuropathy

Wolfgang Drexler

Medical University of Vienna, Vienna, AT

Abstract not received.

SS 15.1 / #150CHANGES IN THE NODAL COMPLEX IN PAINFUL NEUROPATHY

Topic: 12. Patient Issues

Claudia Sommer

Neurologische Klinik Und Poliklinik, Universitätsklinikum Würzburg, Würzburg, DE

Background: Autoantibodies to components of the paranodal protein complex have recently been described and are considered to characterize a subset of immune neuropathies that differs from other subtypes in clinical phenotype pathogenesis and response to therapy. Methods: We systematically screened sera of our patients with suspected immune neuropathies for the presence of autoantibodies to paranodal proteins. We analyzed skin and nerve biopsies for changes in the nodal/paranodal complex. Results: Pain was one of the predominant findings in two patients with anti-caspr antibodies, possibly reflected by binding of patients’ IgG to transient receptor potential vanilloid 1 immunoreactive dorsal root ganglia neurons. Severe disruption of the paranodal and nodal architecture was detectable in teased fibres of the sural nerve biopsy and in dermal myelinated fibres, supporting the notion of the paranodes being the site of pathology. Nodal/paranodal architecture was disrupted in patients with anti-contactin-1 antibodies, but pain was not a prominent feature in these patients. Conclusion: In contrast to other neuropathies with antibodies to the paranodal complex (anti-contactin-1, anti-neurofascin-155) two patients with auto-antibodies against caspr suffered from severe neuropathic pain. The mechanisms underlying this pain need to be uncovered.

SS 15.2 / #86THE USE OF NERVE EXCITABILITY TESTING IN UNDERSTANDING ION CHANNEL DYSFUNCTION IN NEUROPATHY

Topic: 12. Patient Issues

Matthew C. Kiernan

Brain & Mind Centre, University of Sydney, Sydney, AU

Abstract: Measurement of nerve excitability by threshold tracking provides complementary ­information to conventional nerve conduction studies and may be used to infer the activity of a variety of ion channels, energy-dependent pumps and ion exchange processes activated during the process of impulse conduction. While routine nerve conduction studies can document the presence of a neuropathy, they do not provide further insight into pathophysiology. This may be even more relevant across the range of neuropathic syndromes, where conventional nerve conduction studies are often normal. Following the validation of excitability testing protocols, clinical excitability techniques are being adopted to complement diagnostic nerve conduction studies. A number of recent clinical studies will be highlighted which have established mechanisms for neuropathy associated with systemic disease, likely to impact on the future management of patients, both acutely and chronically; provided insight into the mechanisms of painful neuropathies due to neurotoxicity associated with chemotherapy; determined mechanisms of hyperexcitability, further contributing to symptoms of neuropathy. While clinical nerve excitability studies are still in their relative infancy, and it is too early to know whether they have diagnostic value, there is growing evidence of their utility to provide novel insights into the pathophysiological mechanisms involved in a variety of neuropathic disorders.

SS 15.3 / #43HUMAN PAIN CHANNELOPATHIES

Topic: 12. Patient Issues

David Bennett

Nuffield Department Of Clinical Neuroscience, University of Oxford / Nuffield, Oxford, US

Abstract: There has been significant progress over the last decade in understanding the ion channels required by sensory neurons to transmit noxious stimuli. Over this same period we have recognized that mutations in such ion channels can result in primary neuropathic pain disorders. An excellent example is the voltage gated ion channel Na_V 1.7 encoded by the gene SCN9a. Loss of function mutations in this ion channel result in congenital inability to experience pain and gain of function mutations can cause a number of distinct neuropathic pain disorders including erythromelalgia, paroxysmal extreme pain disorder and small fibre neuropathy. There is a ­correlation between the impact of mutations on the biophysical properties of the ion channel and the severity of the clinical phenotype. The fact that mutations in such channels can cause monogenic pain disorders makes them attractive analgesic drug targets. Secondary neuropathic pain disorders such as traumatic neuropathy or painful diabetic neuropathy are also associated with altered expression and function of multiple ion channels which contribute to hyperexcitability. Finally we are now beginning to recognize that auto-antibodies to ion channels and proteins with which they complex can cause acquired pain channelopathies. We are trying to improve the stratification of neuropathic pain patients by linking the clinical phenotype with genotype with the ultimate aim of optimizing analgesic drug selection on an individualized basis.

SS 16.1 / #138NIV AND ALS

Topic: 03. Motor Neurone

Marianne De Visser

Department Of Neurology, Academic Medical Centre, Amsterdam, NL

Abstract not received.

SS 16.2 / #109NUTRITION AND ALS

Topic: 03. Motor Neurone

Esther Hobson

University Of Sheffield, Sheffield Institute for Translational Neurosciences, HQ, GB

Background: Malnutrition and weight loss are well recognised poor prognostic factors in amyotrophic lateral sclerosis. Body mass index (BMI) is an independent predictor of survival in ALS, with mild obesity having a protective effect and lower BMI associated with a worse prognosis. In patients with weight loss of 5% or more at diagnosis there is a two-fold increase in risk of death, compared to those who have lost less than 5% of their usual pre-morbid weight. Poor nutrition in ALS is not simply as a result of bulbar dysfunction. Fatigue and poor upper limb dysfunction make feeding difficult whilst respiratory failure cause loss of appetite. As a consequence, eating is no longer a pleasurable and social activity, instead it becomes a burden on the patient and caregiver. The energy deficit caused by inadequate intake is compounded by observed hypermetabolism with resting energy expenditure observed to be, on average, 20% higher than healthy individuals. Patients with hypermetabolism have a greater level of lower motor neuron involvement, faster rate of functional decline and shorter survival compared with normometabolic patients with ALS. Methods: It is suggested that metabolic defects and the energy deficit are not simply a consequence of denervation and advanced disease but are an early feature of ALS pathology. They could therefore be potentially modifiable using dietary interventions. Patients themselves have not waited for evidence with more than half using some dietary supplementation. The consequences of these untested diets remains unclear but thereis some limited evidence that correction of the energy deficit with a high calorie diet extends life in an ALS mouse model.Moreover, a small pilot study of ALS patients indicated a potential survival advantage and tolerability of a high calorie diet. Future research will investigate the potential of calorie manipulation, particularly in the early stages of the disease. Results: Most patients later in the disease course opt for placement of a gastrostomy tube. Despite gastrostomy use being common practice, in the absence of comparative trials it remains difficult to determine the impacts for patient survival and quality of life. However, prospective and observational studies can provide some information. There are a variety of methods available for insertion, each likely to be broadly similar in its insertion risks. Longer term consequences and risk of tube damage or displacement are related to the robustness of the tube. Gastrostomy insertion with traditional feeding techniques alone does not typically reverse weight loss particularly in those who have already lost over 10% of their premorbid bodyweight, in whom, along with those in respiratory failure, the 30 day-mortality is significantly greater. Conclusion: This leads to the conclusion that gastrostomy insertion should be offered early in the disease. However there is often resistance to accepting this procedure due to various psychosocial factors, some of which may be overcome by better information (such as the www.mytube.mymnd.org website). What remains unclear is what is the best nutritional regime post-gastrostomy insertion, and how to communicate the individual risk and benefits, particularly those with a poorer prognosis or those without bulbar disease.

SS 16.3 / #52NUTRITION NIV AND COGNITION IN ALS

Topic: 03. Motor Neurone

Vincenzo Silani

University of Milan Medical School, Milan, IT

Abstract not received.

SS 17.1 / #187NEUROFIBROMATOSIS

Topic: 06. Mononeuropathy

Katharina Wimmer

Medical University of Innsbruck, Innsbruck, AT

Abstract not received.

SS 17.2 / #175PERIPHERAL NERVE TUMORS

Topic: 06. Mononeuropathy

Gelareh Zadeh

University Health Network, Toronto, CA

Abstract not received.

SS 17.3 / #106INTRANEURAL PERINEURIOMA:  MAKING THE DIAGNOSIS AND CLUES TO THE PATHOGENESIS

Topic: 06. Mononeuropathy

Michelle Mauermann

Neurology, Mayo Clinic, Rochester, MN, US

Background: Intraneural perineurioma is a benign peripheral nerve neoplasm composed of whorls of perineurial cells surrounding nerve fibers and restricted to the boundaries of a peripheral nerve. It was previously unclear if these were caused by a genetic abnormality or were related to prior trauma. Methods: To review the clinical, electrophysiological, radiological and pathological features of intraneural perineurioma and its associated natural history. We will discuss how to differentiate these tumors from other benign nerve tumors and inflammatory nerve lesions. The recent advances in the underlying genetic causes will be discussed. Results: Intraneural perineurioma presents insidiously in children and young adults with a motor-predominant mononeuropathy or plexopathy. The sciatic nerve is most commonly affected. The electrophysiological findings demonstrate a chronic axonal process. The radiologic hallmark is fusiform nerve enlargement with T2 hyperintensity and contrast enhancement. Targeted biopsy of tumor demonstrating the typical pathological features is the gold standard for diagnosis. Pathologic features include nerve hypertrophy due to pseudo-onion bulb formations consisting of whorls of perineurial cells surrounding nerve axons that react for epithelial membrane antigen. A recent study led to the discovery of frequent recurrent missense somatic mutations in TRAF7. Rare patients have large somatic macrodeletions and duplications. Conclusion: Intraneural perineurioma is a benign hypertrophic peripheral nerve tumor that presents in young people with a motor-predominant mononeuropathy or plexopathy. It is slowly progressive and causes mild disability. Underlying genetic mutations in TRAF7 suggest a shared pathogenesis with intracranial meningiomas.

SS 17.4 / #1029CANCER AND PERIPHERAL NERVES

Topic: 06. Mononeuropathy

Wolfgang Grisold¹, Anna Grisold², Stefan Meng³, Elisabeth Lindeck-Pozza⁴

¹Ludwig Boltzmann Institute for Experimental und Clinical Traumatology, Vienna, AT;²Dep. Neurology, Allgemeines Krankenhaus Vienna, Vienna, AT;³Institute for Radiology, KFJ hospital, Vienna, AT;⁴Dep. Neurology, KFJ hospital, Vienna, AT

Abstract: Peripheral nerve tumors are rare and are conventionally classified according to the WHO classification 2016, which adds several new entities as hybrid tumors, perineuroma and malignant peripheral nerve sheath tumors (MPNST). In addition to this classification also mesenchymal, vascular and tumor like conditions have to be considered. The neoplastic involvement of peripheral nerves occurs in cancer, lymphoma, leukemia and even more rarely in plasmocytoma. In all cancer patients, MPNSTs can be a side effect of radiation therapy (RT). In solid tumor nerve metastasis, or circular compression of individual nerves is rare, however in the peripheral parts of the cranial nerves infiltration and spread can be observed. Infiltration and compression can also be seen in nerve roots and the nerve plexus. Lymphoma and leukemia can present with isolated appearance or diffuse infiltration, at any time of the disease, also as a recurrence. Also solid manifestations in leukemia termed chloroma are rarely reported. Tumorous infiltration of peripheral nerve by plasmocytoma is are, and also local amyloidomas have been described. For the different tumor entities also different morphological changes and mechanisms are described. Therapy depends on the tumor type and in addition to surgical and RT also chemotherapy or biological therapies depending on the tumor type are used. As in MPNST the prognosis is usually poor.

SS 18.1 / #85MND: THERAPEUTIC LANDSCAPES

Topic: 03. Motor Neurone

Matthew C. Kiernan

Brain & Mind Centre, University of Sydney, Sydney, AU

Abstract: Recent evidence has emerged concerning unique pathophysiological processes linked to the development of motor neurone disease (MND), including glutamate-mediated excitotoxicity, which has resulted in development of novel diagnostic investigations and uncovered potential therapeutic targets. Advances in genetics, including the recently discovered C9orf72 gene, have radically changed the pathological mind-set, such that ALS forms part of a continuum with other primary neurodegenerative disorders, including frontotemporal dementia. At the simplest level, the management of MND remains focused on symptom control. Evidence-based management guidelines advise a multi-disciplinary model of care, led by a neurologist and clinical nurse consultant working together with physical therapists, occupational therapists, speech pathologists, respiratory physicians, gastroenterologists, psychologists and social workers to guide patient management, and such an approach has profoundly impacted patient quality of life and survival. In terms of emerging therapies, there have been several recent phase II/III trials that have recently shown promising results. Data concerning masitinib reported significant improvement from baseline to week 48 in the Revised ALS Functional Rating Scale scores (primary endpoint) and FVC (secondary endpoint). This new oral tyrosine kinase inhibitor regulates abnormal neuroglia activation and proliferation, processes linked to motor neurone death. A clinical trial of ultrahigh-dose methylcobalamin (E0302) significantly prolonged survival in a dose-dependent manner in MND patients who were treated within 1year of disease onset. Edaravone (3-methyl-1-phenyl-2-pyrazolin-5-one), a potent free radical scavenger, is known to prevent neuronal damage inhibiting endothelial injury and is currently marketed for use after ischaemic stroke. Benefit from edavarone was established for a subgroup of MND patients, specifically younger patients with an FVC at least 80%, and with recent onset of symptoms. Other potential treatment targets awaiting confirmation with human clinical trials include CNS copper treatment and anti–human endogenous retrovirus K (HERV K) treatment. Stem cell therapy remains a theoretical possibility: previous attempts to grow anterior horn cells have been abandoned. Now the overall goal is prevention of further neuronal loss by supporting residual motor neurones. The optimal route of administration and specific type of stem cells needed, remain unanswered questions that are currently being considered through several phase II studies.

SS 18.2 / #114TREATMENT STRATEGIES FOR HEREDITARY ALS

Topic: 03. Motor Neurone

Timothy Miller

Washington University, St. Louis, US

Background: Recent discoveries have defined the genetic cause in more than 60% of hereditary ALS. Along with this increased genetic discovery has emerged increased tools to specifically target genes and pathways that cause ALS. Methods: These therapeutic strategies include viral delivered siRNA, antisense oligonucleotides, antibodies, and small molecules. Results: Novel treatment strategies for hereditary ALS will be discussed with a particular focus on antisense oligonucleotides. Conclusion: Treatment strategies for hereditary ALS have tremendous potential to positively impact ALS.

SS 18.3 / #131DIAGNOSIS AND TREATMENT OF MOTOR NEUROPATHIES

Topic: 03. Motor Neurone

Alan Pestronk

Department Of Neurology, Washington University School of Medicine, St. Louis, MO, US

Abstract not received.

SS 19.1 / #139DISTAL HEREDITARY MOTOR NEUROPATHIES (DHMN)

Topic: 03. Motor Neurone

Mary Reilly

Queen Square, Institue Of Neurology, London, GB

Abstract: The distal hereditary motor neuropathies (HMN) are a clinically and genetically heterogeneous group of slowly progressive neuropathies characterised by a distal predominant almost exclusive motor syndrome. There is overlap with the axonal forms of Charcot Marie Tooth disease (CMT2) such that causative genes are often described as causing both HMN and CMT2 (e.g. HSPB1 and HSPB8). The differentiation of these motor predominant syndromes into HMN and CMT2 is artificial as these conditions are motor predominant but especially with time there can be minimal sensory involvement. It may be more appropriate to use the term CMT to include HMN, CMT and the sensory predominant form, HSN, reflecting the spectrum of clinical disease from pure motor or motor predominant (HMN) through motor and sensory (CMT) to pure sensory or sensory predominant (HSN). As multiple causative genes are identified for HMN, it is clear that there is also overlap with other inherited neurological conditions with some genes causing both HMN and hereditary spastic paraparesis (HSP) (e.g. REEP1) and others such as the mitochondrial gene MT-ATP 6 causing a spectrum of neurological conditions including a motor predominant CMT2 like phenotype. Although the traditional definition of distal HMN is a length dependent motor neuropathy starting in the lower limbs many clinical variations are now recognised. Many forms of distal HMN do not present with the typical weak ankle dorsiflexion with relatively preserved ankle plantarflexion reflecting the anterior lower limb muscle involvement seen with CMT and instead present with equal involvement of anterior and posterior calf muscle resulting in equal ankle dorsiflexion and plantarflexion weakness (e.g. this is seen with HSPB1 and HSPB8 mutations). We also now recognise with these same two genes (HSPB1 and HSPB8) that a myopathy can be present as well as a neuropathy. Other genes cause a non length dependent lower limb predominant motor neuropathy (e.g. with Dynein and BICD2). A number of genes (BSCL2, GARS, REEP1) cause a motor syndrome which is much more pronounced in the upper limbs and can involve the upper motor neurone fibers in some cases (BSCL2 can cause Silver syndrome which is characterised by amyotrophy of the hands with spasticity of the lower limbs). The involvement of upper and lower motor neurone fibres is important as it underlies that the pathogenesis of both upper motor neurone motor syndromes (e.g. HSP) and lower motor neurone syndromes (e.g. HMN) is likely to involve common pathways like axonal transport or protein misfolding disorders with the possibility of developing pathway therapies for all axonopathies rather than therapies for each individual genetic condition. This talk will focus on the evolving genotypes and phenotypes and the progress towards therapy development.

SS 19.2 / #32DISTAL MYOPATHIES

Topic: 03. Motor Neurone

Anthony Amato

Dep. Of Neurology, Brigham and Women’s Hospital, Boston, US

Abstract: The distal myopathies are characterized clinically by progressive atrophy and weakness of distal arm or leg muscles and histologically by nonspecific myopathic features on muscle biopsy. The distal myopathies can be subdivided, based on the clinical features, age of onset, CK levels, muscle histology, and mode of inheritance. Myopathic causes of distal weakness are distal muscular dystrophies, of which we would include the myofibrillar myopathies and various, hereditary inclusion body myopathies, congenital myopathies, glycogen and lipid storage myopathies, and acquired forms such as seen in granulomatous myopathy.

SS 19.3 / #84ACQUIRED DISTAL MOTOR SYNDROMES

Topic: 03. Motor Neurone

Matthew C. Kiernan

Brain & Mind Centre, University of Sydney, Sydney, AU

Abstract: Distal or lower motor neuron syndromes are characterised by muscle atrophy, weakness and hyporeflexia without sensory involvement. These disorders may arise from disease processes affecting the anterior horn cell, the motor axon, or its surrounding myelin. Neuromuscular junction pathology and muscle disorders may mimic these disorders and form part of the differential diagnosis. Distal motor syndromes can be broadly classified as hereditary, sporadic or immune-mediated. Immune-mediated neuropathies, such as multifocal motor neuropathy and chronic inflammatory demyelinating polyneuropathy are important to distinguish from sporadic and hereditary forms, as effective treatments are available. Lower motor neuronal presentations of motor neuron disease (MND) are most often sporadic, but several genetic mutations have been described. Hereditary forms include distal hereditary motor neuropathies and spinal muscular atrophy (SMA). With the latter, onset typically occurs during childhood or teenage years, although adult onset is not uncommon. The increasing availability of next-generation sequencing, including the ability for multiple genes to be sequenced in parallel, has resulted in an increase in the discovery of novel genetic mutations. The clinical evaluation of a patient presenting with a distal motor syndrome includes a directed assessment of disease onset and progression. This is particularly important to ascertain, as a rapid rate of decline may suggest a diagnosis of MND and remains an important factor in distinguishing MND from other relatively indolent conditions, such as SMA and immune neuropathies. The pattern of weakness may also suggest a specific diagnosis, with considerations including (1) symmetry versus asymmetry, (2) proximal versus distal involvement, (3) upper versus lower limb predominance and (4) presence versus absence of bulbar involvement. Nerve conduction studies and electromyography are essential to confirm that the disorder is neurogenic and should focus on assessing the pattern of involvement, including symmetry and length dependence; the presence of focal motor conduction block or demyelinating features; and the presence or absence of subclinical sensory abnormalities. Neuromuscular imaging, genetic testing, assessment of antibody markers and advanced neurophysiological techniques are all useful adjuncts to determine a specific diagnosis and the best therapeutic approach.

SS 20.1 / #49EVOLUTION OF MONOCLONAL AB TREATMENT APPROACHES IN MG

Topic: 04. Neuromuscular Junction

Ted M. Burns

Department Of Neurology, University of Virginia, Charlottesville, US

Abstract not received.

SS 20.2 / #136OTHER NOVEL TREATMENT APPROACHES: EXERCISE

Topic: 04. Neuromuscular Junction

Anna R. Punga

Neuroscience, Uppsala University, Uppsala, SE

Background: The benefits of physical exercise for healthy individuals are well established, in particular to reduce the risks of life-style disorders. Furthermore, physical exercise provides beneficial effects in several chronic diseases such as rheumatoid arthritis, chronic obstructive pulmonary disease and multiple sclerosis, and is therefore recommended as part of the treatment regimen. It is reasonable to assume that MG patients achieve at least similar benefits from physical exercise, as do healthy adults. Yet, exercise-related research in the field of MG is sparse and does not provide any guidelines on how MG patients should perform physical exercise to obtain desirable benefits without the risk of causing disease deterioration or more pronounced muscle fatigue. Two recent pilot studies reported that MG patients with mild disease activity could adhere safely to general exercise recommendations including resistance and aerobic training regimen without subjective or objective disease deterioration. Overall, though, there is an obvious lack of literature in the field of physical exercise and MG that hampers the possibility to individualize training programs that could be of particular importance to avoid development of secondary disease conditions. Methods: Two studies were performed: 1) To objectively evaluate functional skeletal muscle parameters in MG patients who conducted a 12-week supervised physical therapy program, focusing on aerobic and high-resistance strength training. 2) A follow-up study on patients for 6 months with an individually tailored program from a personal trainer. The primary hypothesis was that a physical exercise program based on general exercise recommendations improves muscle status in MG patients. The secondary hypothesis was that moderate aerobic and high-resistance strength training improves the cardiovascular risk profile and self-assessed-well-being of MG patients. Both studies were prospective and unblinded, where each patient served as his/her own control. Outcome measures included clinical MG status, isometric muscle force, neurophysiological evaluations, neuromuscular ultrasound, physical performance-based measures, quality of life, fatigue severity and blood sample analysis. Wilcoxon signed-rank test was used to compare non-parametric data before and after training in each patient. A P-value < 0.05 was considered significant. Results: After the training program, functional muscle parameters (neurophysiological parameters, isometric muscle force and ultrasound muscle thickness) improved in the proximal leg muscles. Further, physical performance-based measures improved as well as the clinical MG composite score. The longer follow-up study also indicated positive adherence to individualized programs and additional beneficial effects. Conclusion: These findings indicate that MG patients can indeed improve their functional muscle status as a result of aerobic and high-resistance strength training, especially in proximal leg muscles. This is important knowledge in order to establish both collective as well as individualized guidelines of physical exercise for MG patients.

SS 20.3 / #174OVERVIEW OF TREATMENT GUIDELINES: GOING FORWARD

Topic: 04. Neuromuscular Junction

Gil I. Wolfe

Neurology, University at Buffalo Jacobs School of Medicine and Biomedical Sciences, Buffalo, NY, US

Background: The rarity of myasthenia gravis (MG) makes the planning and completion of randomized controlled trials (RCTs) logistically difficult with many trials failing to reach their recruitment goals. Due to restricted entry criteria that are often an essential element of well-designed RCTs, results from these studies may also have limited generalizability to the overall patient population. Furthermore, the majority of trials do not address the comparative effectiveness of different treatment modalities in a disease as heterogeneous as MG. As a result, most current treatments for MG are based on uncontrolled studies, with a high risk of bias. Recommendations based on a formalized consensus opinion of experts can help to guide treatment in such situations. Methods: To review treatment recommendation statements that have been produced recently by neuromuscular neurology experts in several European and Asian countries and to describe the process and results generated by an international panel that focused on several treatment domains related to MG. Plans for future revisions to the statements will also be presented. Results: Since 2012, treatment recommendations for MG have been established and published by several countries, beginning with Germany and including England, Japan and China. Of these national statements, only the Chinese employed a formal consensus process, using the RAND/UCLA appropriateness method (RAM). In October 2013, the Myasthenia Gravis Foundation of America (MGFA) appointed a Task Force to develop treatment guidance for MG, and a panel of 15 international experts was convened. The panel also included a facilitator with extensive experience in consensus methodology and an observer representing patient interests from the MGFA. RAM methodology was used to develop consensus guidance statements. To frame the treatment guidance the following definitions were established by the panel: goals of treatment, minimal manifestations, remission, ocular MG, impending crisis, manifest crisis, and refractory MG. An in-person meeting of the panel then determined 7 treatment topics to be addressed. Initial guidance statements were developed based on summaries of the literature for each topic. Three rounds of anonymous e-mail votes with modifications of the guidance statements, based on panel input were used to reach consensus. Guidance statements were developed for the following MG treatment domains: symptomatic and immunosuppressive treatments, intravenous immunoglobulin and plasma exchange, management of impending and manifest myasthenic crisis, thymectomy, juvenile MG, MG associated with antibodies to muscle specific tyrosine kinase and MG in pregnancy. Conclusion: Both national and international treatment recommendations have helped define best practices in the management of MG. Although there are common threads across the various recommendations, differences do exist that reflect national practice and the availability or approval of treatment modalities. The formal international consensus can serve as a guide for clinicians who wish to optimize function and quality of life for their MG patients. It may be of particular benefit to those clinicians who practice in countries that do not have the resources to generate a national treatment statement. The international guidance is a living document that will require revision every few years to reflect developments in the field.

SS 21.1 / #67NEUROLOGICAL COMPLICATIONS OF ZIKA VIRUS

Topic: 09. Systemic Diseases

John D. England

LSUHSC School of Medicine, New Orleans, US

Abstract: Zika virus (ZIV) is a mosquito-borne single-stranded RNA virus in the Flaviviridae family. On 1 February 2016 the World Health Organization (WHO) declared ZIV infection a Public Health Emergency of International Concern (PHEIC) due to reports from Brazil of a cluster of microcephaly cases and other neurologic disorders termed Congenital Zika Syndrome as well as clusters of Guillain-Barre Syndrome (GBS) from French Polynesia and South America. Since that time an expanding spectrum of neurological complications of Zika virus infection have been described. ZIV is now recognized as a new neuropathological agent associated with a wide variety of neurological complications. These neurological sequelae of ZIV infection represent both direct effects of virus invasion and autoimmune responses to the virus. The neurological complications of ZIV include the following: 1) Congenital Zika Syndrome associated with infection of neural progenitor cells in the brain; 2) Guillain-Barre Syndrome (GBS), which is most likely caused by a secondary autoimmune response directed against components of peripheral nerve; 3) Sensory polyneuropathy, which may be associated with direct infection of peripheral neurons; 4) Encephalitis/meningoencephalitis and myelitis, which may be associated with direct viral infection/inflammatory process in the central nervous system; 5) Acute Disseminated Encephalomyelitis; 6) Optic neuropathy; 7) Arterial Ischemic Stroke (AIS) in children due to probable vasculitis and possible direct ZIV infection of brain endothelial cells. Ongoing investigations are confirming these associations and exploring the pathogenesis of the complications of ZIV infection. Since there is no specific treatment for ZIV infection, public health measures are directed at prevention of primary infection.

SS 21.2 / #146LEPROUS NEUROPATHIES

Topic: 09. Systemic Diseases

Gerard Said

Institut Vernes, PARIS, FR

Abstract: Leprous neuropathy, which is due to infection of nerve cells by Mycobacterium leprae remains a health problem worldwide. In addition to being an infectious and potentially contagious disease, it induces irreversible damage to peripheral nerves, exposing patients to lifelong complications of sensory and motor denervation. The number of new cases reported globally in 2016 exceeds 200 000 with 135 485 in India, 25 218 in Brazil and 16 826 in Indonesia. Nasal secretions and skin from untreated multibacillary leprosy (ML) cases can contaminate contacts. The incubation period may be as long as 20 years. Factors such as nutrition, hygiene and house crowding play an important role.M. leprae is an obligatory intracellular parasite with tropism for macrophages and Schwann cells. The bacillus attaches to Schwann cells via PGL-1. Once inside the Schwann cell, the mycobacterium will multiply very slowly, triggering a subacute to chronic inflammatory reaction, with replacement of functional parenchymal tissue by connective tissue and fibrosis. In the multibacillary type bacilli are easily found in the skin, and in nerve cells including Schwann cells, endothelial cells and macrophages. Conversely, in the paucibacillary (or tuberculoid) type a strong cell mediated immune reaction leads to granulomas formation and destruction of cells harbouring bacilli and nerve fibres nearby. In many cases treatment of patients with multibacillary leprosy is complicated by early or late reversal reaction, and further nerve damage. Nerve lesions lead to a symmetrical, pseudo-polyneuritic pattern, in most cases of multibacillary leprosy (ML), usually associated with typical skin lesions. In 10% of patients however skin lesions are missing, then only nerve biopsy permits diagnosis. The multifocal pattern, is more common in paucibacillar leprosy. Clinical manifestations of leprous neuropathy include 1. Specific cutaneous lesions, which reveals the disease in half or more of the patients, depending on the type of leprosy. 2. Sensory loss is the most constant neurological finding, due to the involvement of mixed dermal nerves and nerve trunks. Proprioception is often preserved, so patients can still use their largely anaesthetic limbs effectively, which leads to painless trauma and trophic changes. The topographical distribution of sensory disturbances is extremely variable. 3. Motor involvement is a late event in the course of the disease. Amyotrophy and motor weakness usually progress pari passu. They predominate in the ulnar and median nerve territories, with characteristic claw hands, and in the territory of the peroneal nerve. 4. Tendon reflexes are often preserved 5. Nerve hypertrophy: Nerve trunks are palpably enlarged in one third of the patients with leprosy, sometimes before the occurrence of sensory loss in the corresponding territory. Doppler ultrasound can be useful in this setting. 6 There is no dysautonomia or sphincter disturbances 7. Facial palsy with lagophthalmos of one or both eyes, with sparing of the other muscles supplied by the facial nerve is a classical feature. 8. Trophic disturbances are the most spectacular manifestations of leprosy. Severe sensory loss is always found in those areas where ulcers occur. 9. Symptomatic neuropathy, which is usually preceded by alteration of conduction velocity due to demyelination of nerve fibers, is invariably associated with major axonal damage and loss of more than 90% of nerve fibres in corresponding territory. Treatment is currently based on multidrug therapy with dapsone, rifampicin and clofazimine. The use of corticosteroids can reduce or prevent nerve damage in reversal reactions. Residual sensory loss which is extremely common in affected areas, can lead to trophic changes related to repeated traumas in painless areas.

SS 21.3 / #301NEUROPATHIES IN INFECTIOUS DISEASES

Topic: 09. Systemic Diseases

Nazha Birouk

Clinical Neurophysiology Rabat, Speciality Hospital, Rabat, MA

Abstract: Infectious neuropathies are heterogeneous group of neuropathies regarding their multiple causes and numerous clinical presentations. They till represent an important world health issue. The clinical presentations are variable including symmetric distal neuropathy, mononeuropathy multiplex, radiculopathy or cranial neuropathy. The disorder process can be acute, sub acute or chronic axonal or demyelinating and is diagnosed by eletrodiagnostic or in some situations by nerve biopsy. The infectious agent can involve the peripheral nerve directly or indirectly by autoimmune and/or inflammatory process. The HIV related neuropathy became the major complication of HIV infection. The most frequent form is the painful distal and symmetric lent dependent polyneuropathy; it can be either HIV induced or antiretroviral toxic neuropathy. Inflammatory neuropathies such as acute or chronic polyradiculoneuropathies can be encountered at early stage of HIV infection. In the later stages, HIV infected patients can present with acute radiculopathies due to CMV infection. Peripheral neuropathy in patients with chronic infection with hepatitis C virus is mainly due to associated cryoglobulinemia and the associated vasculitis that leads to acute or sub acute mononeuritis multiplex. The polyneuropathy in this context can be also induced by direct neurotoxic effect of the treatment. In Lyme disease the involvement of peripheral nerves is part of meningoradiculitis with frequent involvement of cranial nerves. The most frequent infectious neuropathy in the world remains an active infectious ganglioneuritis caused by varicella zoster virus, producing shingles. The main issue with this condition is the post-herpetic neuralgia that can be severe in some patients. Infectious diseases are an important part of differential diagnosis of peripheral neuropathies because most of them are potentially treatable. The systematic diagnosis for the most frequent ones such as HIV and hepatitis C is highly recommended in a patient with polyneuropathy. Other infections are discussed regarding particular clinical presentations and in some geographic areas.

SS 21.4 / #866INFECTION RELATED NEUROMUSCULAR DISORDERS (NEUROPATHIES AND MYOPATHIES)

Topic: 09. Systemic Diseases

Chandrashekhar Meshram

Neurology, Brain and Mind Institute, Nagpur, IN

Background: Various bacterial, viral and parasitic infections directly or indirectly affect peripheral nerves and muscles. Neuromuscular disorders can be caused by three mechanisms : direct infection, infection related but toxin mediated and post infectious syndrome. Involvement of nerves and muscles secondary to systemic infections is relatively rare phenomenon. Some of these infections are sporadic, while some occur in outbreaks. Some infections are predominantly observed in tropical countries. During outbreaks, cases are observed in clusters in affected regions and one gets the opportunity to study the disorders. Methods: Personal experience and unpublished personal communication was supplemented by search of published literature on neurological manifestations of systemic infections with involvement of peripheral nerves and/or muscles. Special attention was given to evaluate neuromuscular involvement in Chikungunya, Dengue, Leptospirosis, Scrub Typhus and Rabies. Results: During the Chikungunya epidemic in India in 2006 , Peripheral Neuropathy was observed in 36 % patients with neurological involvement ,entrapment neuropathy was seen in 10 % while myositis was noted in 15 % patients.In many patients there was combination of central and peripheral manifestations. Polyradiculoneuropathy ,lumbosacral plexopathy ,GBS have been reported with Dengue virus infection. Autonomic symptoms are common and may occur in 30 % patients. These features are mainly immune mediated. Dengue associated hypokalaemic paralysis and myositis is also reported. A more benign and common, transient muscle weakness with moderately raised CPK is usually self limiting. But sometimes the myositis can be fulminant and require respiratory support. In Neuroleptospirosis, peripheral nervous system involvement is seen in 10 % patients in form of myositis, rhabdomyolysis, GBS like presentation , brachial neuritis and mononeuritis multiplex. However CPK is raised in 30- 50 % patients. Neurological involvement occurs in 25 % patients of Scrub Typhus. Neuromuscular involvement is in form of cranial nerve dysfunction, peripheral neuropathy, and myositis.In one study 39 % patients of Scrub typhus had muscle involvement in form of myalgia,weakness,raised CPK and myopathic EMG. Twenty percent patients of Rabies present with ascending paralysis. Pain and paraethesia at the site of bite are common symptoms. Both upper and lower limbs are involved. Sometimes weakness is limited to the bitten limb. Conclusion: Neuromuscular manifestations associated with systemic infections, though uncommon should be considered in diffential diagnosis. Involvement is variable in severity and sometimes they occur in combination. Early detection and appropriate treatment helps in reducing the morbidity and mortality.

SS 22.1 / #82THE HISTORY OF NEUROMUSCULAR DISEASES AND THEIR TREATMENT IN HABSBURG COUNTRIES

Topic: 10. History

Sonja Horn

University of Vienna, Vienna, AT

Abstract: Research on neuromuscular diseases and their therapy in history is usually covered under the notion of ”electrotherapy” – at least in the Habsburg inherited countries. Electrotherapy was used to treat soldiers of the Habsburg army already in the late 18^thC., however there are also distinctive reports about the frequent use of electrotherapy at the Vienna clinic during the mid 18^th C. Perhaps as a typical way of practicing medicine at Vienna, the treatment of patients at hospitals in was intensely linked to the training of physicians and surgeons, as well as to post mortem dissections and theoretical research. Therefore ”electrotherapy” has to be seen as strongly linked to theoretical and experimental research on the function of nerves and muscles as well as on the anatomy of the brain and the ”location” of intellectual functions. This concept of the production of medical and scientific knowledge was practiced not only at Vienna, but also at other universities in the Habsburg countries like Prague or Pavia, that are connected with researchers like Jan Evangelista Purkinje (1787 – 1869), Alessandro Volta (1745 – 1827) or Camillo Golgi (1843 – 1926). In my paper I will focus on concepts and topics of research on neuromuscular diseases, which is strongly linked to the practical use of electrotherapy.

SS 22.2 / #31HISTORY ON NM DISEASE

Topic: 10. History

Richard J. Barohn

Neurology, University of Kansas Medical Center, Kansas City, KS, US

Abstract: MG was suspected as a disease probably since Thomas Willis first wrote about ”the palsy” in the late 1600s. In the late 1800s, MG was defined as a clinical entity by German neurologists; Wilhelm Erb, Samuel Goldflam, Herman Oppenheim, and Friedrich Jolly described the decremental muscle response on electrophysiologic testing. In the first half of the twentieth century. The two discoveries that led to a better understanding of MG involved the thymus gland’s relation to MG and the drug treatment for MG using acetylcholinesterase inhibitors. Sauerbach first successfully removed an enlarged thymus gland in 1911. In the 1930s and 1940s, Blalock advocated and began performing thymectomy for MG patients with and without thymoma. Mary Walker in England was the first to observe the drugs physostigmine and neostigmine improved MG patients. In the second half of the twentieth century a number of discoveries occurred: (1) an understanding of the neuroanatomy and neurochemistry of the NMJ; (2) development of the animal model of experimental allergic MG; (3) the discovery of antibodies to the acetylcholine receptor (AChR) in humans with MG and passive transfer of MG to mice from human immunoglobulin of MG patients; (4) passive transfer of MG to mice from human immunoglobulin of MG patients; (5) the discovery that corticosteroids and other immunosuppressive agents, including plasmapheresis, can improve MG symptoms and signs; and finally, (6) the development of mechanical ventilation to keep patients alive when they go into respiratory failure from myasthenia crisis; (7) improvement in electrophysiologic techniques for diagnosing MG, and the development of single fiber EMG. In the 1950s, the disorder known as LEMS was described, initially in patients with cancer and later in noncancer patients. In the 1970s, the first congenital myasthenic syndrome was described. In the current era, new autoantibodies are being discovered that are responsible for NMJ disorders (voltage-gated P-/Q-type calcium channels in LEMS; to LRP4, rapsyn, agrin, and cortactin in MG). We now have a great deal of experience in clinical research in MG and have refined the endpoint measurements and trial designs. With the completion and publication of the landmark thymectomy trial in MG, we can now say with conviction that patients with MG who undergo thymectomy improve and their prednisone dose can be lowered more than patients who do not have a thymectomy. Prior to 2000, there were only seven randomized controlled published MG trials. As of 2018, 22 randomized clinical trials have been published for MG. Recently, this led to the US Food and Drug Administration approval of the complement inhibitor eculizumab (Soliris) for adult patients with generalized MG who are AChR antibody positive. Prior studies demonstrated increased complement in the serum of MG patients and the presence of complements at the NMJ in MG. MG indeed used to be a grave disease with 30%mortality. Now, with the advent of all the advances and others described above, everyone we see with MG should improve, and it should be a rare event indeed for a patient to die of MG.

SS 22.3 / #177ANDALUSIAN NEUROLOGY OVER 700 YEARS

Topic: 10. History

Raad Shakir

World Federation of Neurology, London, GB

Abstract: I will confine myself to the evolution of Medicine and Neurology in Andalusia 711-1492 AD. These centuries saw the massive proliferation of not only Sciences and Philosophy but were the vehicle of transfer of Greco-Roman literature back to Europe. There are numerous scholars and physicians who influenced our thinking and practice. Four will be discussed Averroes (1126-1198), Maimonides (1135-1209), Avenzoar (1094-1161) and Abulcasis (936-1013). The first three were contemporaneous and influenced each other. Each has contributed in a rather unique way to medicine with some emphasis on Neurology and the diseases of the nervous system. Averroes was a defender of the Aristotelian philosophy and is considered to be the father of secular thought in Europe. Maimonides in addition to being a first class physician and the private physician of Saladin was a most respected Torah scholar and theologian. Avenzoar was probably the first physician to practice surgery on animals before trying them on Humans. Abulcasis was a brilliant surgeon and his neurosurgical tools in treating hydrocephalus as an example, were ingenious to say the least. The Golden age of Andalusia was at its zenith during the 10^th to the 12^th century.

SS 23.1 / #42THYMECTOMY FOR MYASTHENIA GRAVIS

Topic: 04. Neuromuscular Junction

Richard J. Barohn

Neurology, University of Kansas Medical Center, Kansas City, KS, US

Abstract: Thymectomy has a central role in the treatment of MG. In thymomatous MG, the tumor should be removed. Along with thymoma, the entirety of the thymus tissue should be removed. Improvement in myasthenic symptoms may or may not follow. A systematic review of the existing thymectomy literature emphasized this knowledge gap and recommended the MG field perform a randomized, controlled trial. (Gronseth and Barohn, 2000) However, owing to the difficulty of performing controlled trials involving thoracic surgery in a rare disease, high-quality evidence about thymectomy had been lacking. A recently completed landmark international, randomized, rater-blinded clinical trial controlling for medical treatment was designed to address this uncertainty. One hundred twenty-six recently diagnosed patients, ages 18 through 65 with AChR antibody–positive generalized MG were randomized to receive either extended transsternal thymectomy plus prednisone versus medical management with prednisone. Over a 3-year follow-up period, the time-weighted average QMG score was lower in the patients who underwent thymectomy (6.15 vs 8.99; P<.001) Similarly, the thymectomy group had a lower time-weighted alternate-day prednisone dose requirement (initially reported at 44 mg vs 60 mg; P<.001), which was later corrected to 32 mg versus 54 mg (95% confidence interval, 12-32 mg; P<.001). Also in the thymectomy group, there were fewer patients requiring additional immunosuppression, fewer adverse events, and fewer admissions for myasthenic crises. These data provide support for thymectomy as a first-line treatment modality that can improve MG status and decrease the required dose and duration of immunotherapy in generalized MG. (Surprisingly, the effects of the thymectomy could be observed as early as 3 to 4 months and were maintained for the entire 3-year study.) Patients with persistent bulbar, respiratory, or limb weakness should be treated with PLEX before surgery. Thymectomy in MuSK, LRP4, and agrin antibody–positive patients is not supported by current evidence. Patients with MG with MuSK antibodies were not included in the recent thymectomy study. Nevertheless, MuSK and ”double-negative” antibody patients have undergone thymectomy and anecdotally have done well. Similarly, there is limited evidence to support thymectomy in patients with ocular MG, although if the patient is AChR antibody positive, it may be considered in refractory cases. The recently completed thymectomy trial mandated a sternal-splitting procedure. Several new less invasive procedures are now being used for thymus removal. Video-assisted thoracoscopic surgery and robotic approaches to thymectomy such as robotic video-assisted thoracoscopic surgery offer shorter hospital durations of stay and limited morbidity have emerged as alternatives to the classic transsternal approach. There are no trials comparing these surgical techniques, however, and available reports suggest comparable results.

SS 23.2 / #173RANDOMIZED CONTROLLED TRIAL OF THYMECTOMY: A DEEPER DIVE INTO DATA

Topic: 04. Neuromuscular Junction

Gil I. Wolfe¹, Henry J. Kaminski², Inmaculada B. Aban³, Greg Minisman⁴, Hui-Chien Kuo³, Joshua R. Sonett⁵, Alexander Marx⁶, Cleo-Aron Weis⁶, Gary R. Cutter⁷

¹Neurology, University at Buffalo, Buffalo, NY, US;²Neurology, George Washington University, Washington, DC, US;³Biostatistics, University of Alabama at Birmingham, Birmingham, AL, US;⁴Univesity of Alabama at Birmingham, Birmingham, AL, US;⁵General Thoracic Surgery, Columbia University Medical Center, New York, NY, US;⁶Pathology, University Medical Centre Mannheim/University of Heidelberg, Mannheim, DE;⁷Biostatistics, UNiversity of Alabama at Birmingham, Birmingham, AL, US

Background: MGTX, the Thymectomy Trial in Non-thymomatous Generalized Myasthenia Gravis Patients Receiving Corticosteroids, was the first-ever randomized, rater-blinded study of thymectomy in myasthenia gravis (MG). The international trial addressed questions regarding the efficacy of thymectomy in non-thymomatous MG that had persisted for 75 years since use of the procedure was first reported by Blalock and colleagues in 1941. Methods: MGTX was designed to answer three questions: does the combination of alternate-day prednisone and extended transsternal thymectomy after 3 years compared to an identical dosing protocol of prednisone alone, (1) lead to better outcomes in MG as measured by a time-weighted average of the Quantitative MG Score (QMG), (2) reduce the time-weighted average alternate-day prednisone requirements, and (3) reduce side-effect burdens on patients primarily arising from medications used to treat the disease? Patients age 18 to 65 years with generalized non-thymomatous acetylcholine receptor antibody-positive MG of less than 5 years duration and MG Foundation of America Clinical Classification 2 to 4 were enrolled. Dual primary outcomes were the time-weighted average of the Quantitative MG (QMG) score and prednisone dose over 3 years. Results: A total of 126 MG patients underwent randomization at 36 sites. Subjects who underwent thymectomy showed significant improvements in MG status (time-weighted average QMG 6.15 vs. 8.99, p<0.001) and reduced alternate-day prednisone requirements (32 mg vs. 54 mg, p<0.001) at 3 years with benefits observed as early as 9 to 12 months. The ability to withdraw completely from prednisone and remain off it at 3 years also favored the surgical arm (58% vs. 20%, p<0.01). The ability to withdraw from prednisone did not correlate with duration of disease, or age at MG onset or trial enrollment. Histological analysis of thymic follicular hyperplasia, seen in 67% of surgical patients, failed to correlate with the time-weighted QMG or prednisone exposure. However, intra-thymic fat content directly correlated with time-weighted prednisone exposure (p=0.004). On secondary outcomes, fewer patients who had thymectomy required immunosuppression with azathioprine (17% vs. 48%, p<0.001) or were hospitalized for exacerbations (9% vs. 37%, p<0.001). The number of patients with treatment-associated complications did not differ significantly between groups (p=0.73), but the thymectomy group had fewer treatment-associated symptoms (p<0.001) and lower distress levels related to symptoms (p=0.003). MG-Activities of Daily Living scale and the proportion of patients reaching Minimal Manifestation Status also significantly favored the surgical arm. Conclusion: MGTX provided a definitive answer sought by the MG community since the middle of the last century. Extended transsternal thymectomy performed within the first 5 years of disease improves clinical outcomes, reduces immunosuppressive medication requirements, and decreases side-effect burdens in generalized acetylcholine receptor antibody- positive MG patients without thymoma. This group represents the largest subpopulation of MG patients. Although the MGTX trial did not test less-invasive approaches for removing the thymus gland which have become increasingly popular over the last two decades, one can surmise that less invasive approaches that completely replicate the maximal tissue resection performed in an extended transsternal thymectomy would confer similar benefits for patients.

SS 23.3 / #104PATHOLOGY OF THE THYMUS GLAND IN MG

Topic: 04. Neuromuscular Junction

Alexander Marx

Pathology, University Medical Centre Mannheim/University of Heidelberg, Mannheim, DE

Abstract not received.

SS 24.1 / #214SYNAPTIC STABILITY IN CMS

Topic: 04. Neuromuscular Junction

David Beeson

Nuffield Department Of Clinical Neurosciences, University of Oxford, Oxford, GB

Abstract not received.

SS 24.2 / #218RECENT PROGRESS IN UNDERSTANDING PRESYNAPTIC CONGENITAL MYASTHENIC SYNDROMES (CMS)

Topic: 04. Neuromuscular Junction

Hanns Lochmüller¹, Emily O’Connor², Grace Mcmacken², Yoshiteru Azuma², Sunitha Belaraju², Teresinha Evangelista², Roger Whittaker³, Ana Töpf⁴, Andreas Roos⁴, Rita Horvath⁴

¹Department Of Neuropediatrics And Muscle Disorders, Freiburg University - Medical Center, Faculty of Medicine, Freiburg, DE;²Institute Of Genetic Medicine, Newcastle University, Newcastle, GB;³Institute Of Neuroscience, Newcastle University, Newcastle, GB;⁴John Walton Muscular Dystrophy Research Center, Newcastle University, Newcastle, GB

Background: Neuromuscular junction disorders, also called Myasthenic syndromes (MS), are a rare heterogeneous group of acquired (Myasthenia Gravis, MG) and inherited (Congenital Myasthenic Syndromes, CMS) neuromuscular disorders associated with distinctive clinical, electrophysiological, laboratory and ultrastructural abnormalities. The genetic defects in CMS either impair neuromuscular transmission directly or result in secondary impairments, which eventually compromise the safety margin of neuromuscular transmission and may affect proteins that are specific to the synapse or more widely expressed proteins. Methods: While the majority of patients with CMS harbours mutations in genes encoding postsynaptic proteins, defects in presynaptic proteins are increasingly discovered, often associated with additional symptoms of the PNS or CNS. Results: Mutations in SYT2, the gene encoding synaptotagmin 2 are dominantly inherited and show signs reminiscent of hereditary motor neuropathies and fatigability. Mutations in several presynaptic genes are causing severe childhood disorders with episodic apnea or intellectual disability. Loss of MYO9A, a recently identified CMS-associated protein, affects the neuronal cytoskeleton and leads to impaired transport of proteins, including agrin, which may provide a new and unexpected treatment option. Conclusion: We will cover the significant progress made in understanding the molecular pathogenesis of CMS, which is important for both patients and clinicians in terms of reaching a definite diagnosis and selecting the most appropriate treatment.

SS 24.3 / #225CLINICAL ASPECTS OF CMS

Topic: 04. Neuromuscular Junction

Hakan Cetin

Department Of Neurology, Medical University of Vienna, Vienna, AT

Background: Congenital myasthenic syndromes (CMS) are a heterogeneous group of inherited disorders of the neuromuscular junction (NMJ). They are caused by mutations in genes that code for proteins affecting NMJ structure and function. The genetic defect can be located at the presynaptic nerve terminal, the synaptic cleft and the postsynaptic membrane. More recently, next-generation sequencing techniques have also identified causative genes encoding ubiquitously expressed molecules, the functional defect of which, however, may be largely restricted to the NMJ. Methods: Postsynaptic NMJ defects including i) acetylcholine receptor (AChR) deficiency syndromes, ii) slow-channel CMS, iii) fast channel CMS, iv) low conductance CMS and v) CMS due to perturbation of the AChR clustering pathway are reviewed and correlated with clinical findings. Results: Mutations in the AChR subunit genes cause a primary AChR deficiency at the endplate. AChR deficiency syndromes show a recessive inheritance pattern. Disease severity is variable but weakness is usually evident at birth or within the first year of life. Feeding difficulties, ptosis, impaired eye movements and delayed motor milestones are frequent. The disease course is usually not progressive and the patients sometimes improve by early adulthood. Loss of endplate AChR may also be due to the recessive inheritance of RAPSN mutations. The more common ”early onset” form of the disease is associated with hypotonia, bulbar dysfunction and joint contractures of hands and ankles. Affected neonates often require assisted ventilation. By contrast, ”late onset” forms begin from early adulthood and are not associated with bulbar, speech and respiratory problems. They may be mistaken as seronegative myasthenia gravis, but weakness of ankle dorsiflexion may be a helpful clinical tool to differentiate CMS from autoimmune myasthenia gravis. Other AChR subunit mutations predominantly affect ion channel kinetics without a severe reduction of AChR numbers. Slow-channel CMS forms are characterised by longer AChR burst durations. This is associated with prolonged endplate potentials resulting in a depolarisation block of voltage-gated sodium channels. Slow-channel CMS shows a dominant inheritance pattern but there can be variable penetrance, age of onset and disease severity. However, weakness of cervical and scapular muscles and finger extensors is often an early feature. Repetitive compound muscle action potentials to single nerve stimuli in electrodiagnostic studies are characteristic. Fast-channel CMS, by contrast, is characterised by shorter AChR burst-duration and endplate potentials that fail to elicit action potentials in the muscle cell. They have recessive inheritance. Feeding difficulties, ptosis, impaired eye movements and delayed motor milestones are often present at birth with the patients generally more severely affected than in AChR deficiency syndromes. Low-conductance CMS is also inherited recessively. It is very rare and the phenotype is similar to fast-channel syndrome. Mutations in the AChR clustering pathway including agrin, LRP4, MuSK and DOK7 are characterised by a limb-girdle distribution of weakness. Patients may achieve normal walking milestones but then start to experience falls associated with proximal muscle weakness. Conclusion: A deep understanding of disease mechanisms underlying CMS is crucial in order to correlate diagnostic and clinical findings with corresponding molecular defects and thus direct genetic screening and effective treatment.

SS 24.4 / #312THERAPEUTIC STRATEGIES FOR CONGENITAL MYASTHENIC SYNDROMES

Topic: 04. Neuromuscular Junction

Jacqueline Palace

Neurology, Oxford univeristy Hospitals Trust, DU, GB

Abstract: The congenital myasthenic syndromes (CMS) are a heterogeneous group of genetic disorders which cause neuromuscular junction dysfunction. More than 30 different genes have been described as causing CMS and the treatment regimes vary, dependent upon the CMS subtype. For example pyridostigmine and 3,4-Diaminopyridine improve muscle strength in many genetic forms of CMS but make others worse. The mainstay of treatment remains anticholinesterases, in particular pyridostigmine, which improves strength in AChR deficiency syndromes due to epsilon subunit mutations, the fast channel syndromes and CMS due to mutations in RAPSN, CHAT, and glycosylation pathways genes. 3,4-diaminopyrodine (3-4DAP) can also be beneficial in the same conditions (although because acetylcholine is deficient in CHAT CMS increasing the presynaptic release with 3,4-DAP may not be a good strategy). Oral salbutamol or ephedrine are beneficial in DOK7 and COLQ CMS and other forms of CMS where the AChR clustering pathway is impaired. It can also improve strength in forms of CMS where pyridostigmine is being taken at higher doses such as in patients with AChR epsilon mutations causing deficiency of the receptor, and in patients with fast channel CMS. Fluoxetine (usually at doses of 40-100mg daily) or quinidine are the main treatment options for slow channel syndrome CMS. Prolonged QT interval may limit the dose and needs monitoring. It is important to note that pyridostigmine (and 3,4-DAP) usually worsen slow channel syndromes, COLQ and DOK7 CMS and thus where CMS is suspected as a diagnosis, genetic screening of these genes should be undertaken prior to initiating anticholinesterase medication.

WS 1.1 / #181CHEMOTHERAPY INDUCED PNP

Topic: 06. Mononeuropathy

Anthony Windebank

Mayo Clinic, Rochester, US

Abstract not received.

WS 1.2 / #185IATROGENIC MONONEUROPATHIES AFTER SURGERY AND TRAUMA

Topic: 06. Mononeuropathy

Tatjana Paternostro-Sluga

Social Medical Center East - Donauspital, Institute of Physical Medicine and Rehabilitation, Vienna , AT

Background: Iatrogenic mononeuropathies after surgery and trauma occur accidentally or may be part of the necessary treatment. It is of utmost importance to diagnose the lesions immediately and to start the appropriate treatment early. Even so iatrogenic mononeuropathies have always occurred and will occur in the future, the delayed timing of diagnosis and treatment is highly prevalent. Mononeuropathies may interfere significantly with activities of daily living and reduce the quality of life. Patients may recover completely from the primary disease, but the sequelae of the iatrogenic nerve lesion leads to long-lasting impairment and loss of social participation. Methods: The aim of the workshop is to increase the knowledge on iatrogenic nerve lesions and therefore improve diagnostic and therapeutic procedures for the patients. Results: Iatrogenic nerve lesions can result from different surgical procedures. In the upper extremity median nerve, accessory nerve, ulnar nerve, radial nerve, cervical and brachial plexus, axillary nerve and phrenic nerve may be typically affected. Lesions of the median nerve occur most frequently during carpal tunnel surgey, accessory nerve lesions result from lymph node biopsy in the posterior neck triangle and even this is common knowledge it still occurs. The ulnar nerve is frequently associated with supracondylar humeral fractures in children. This has to be taken into account when children with supracondylar humeral fractures are examined. Ulnar nerv palsy in small children may be overlooked at the beginning, especially when atrophy of the intrinsic muscles is not yet visible and finger abduction is done by radial innervated extrinsic finger extensors. In the lower extremity peroneal nerve, femoral nerve, ischiadic nerve, tibial nerve , ilioinguinal and genitofemoral nerves, lateral cutaneous femoral nerve, lumbosacral plexus, saphenous nerve and infra-patellar branch and sural nerve may be typically affected. Orthopedic and gynecological procedures may affect the ischiadic nerve, orthopedic procedures may also affect the femoral nerve and/or the gluteal nerves in total hip replacement. Knee surgery may affect the tibial nerve or the infra-patellar branch of the saphenous nerve. Tourniquet pressure at the thigh during knee surgery might be associated with femoral nerve palsy and a partial lesion might be overlooked. Weakness and insecurity of walking is wrongly attributed to the knee surgery. Conclusion: Prognosis of iatrogenic mononeuropathies depends on the degree of the lesion. The timing for nerve reconstruction is very important to optimize the outcome in high grade lesions. Diagnostic procedure include history, clinical examination, clinical electrophysiology, nerve ultrasound and magnetic resonance imaging. Conservative treatment has to include pain managment, maintenace of range of motion of joints and tendons, motor and sensory reeducation, minimizing trophic disturbances and regaining function. Surgical treatment includes primary nerve repair, nerve reconstruction, neurolysis. Secondary reconstructive procedures, eg muscle transposition may be applied if nerve regneration even after nerve surgery is not sufficient for regaining function. Knowledge, expertise and dedication in diagnosing and treatment of peripheral nerve lesions as well as interdisciplinary and multiprofessional teamwork are the landmarks of best practice in the treatment of iatrogenc nerve lesions.

WS 2.1 / #156DUX4, ITS ROLE IN DEVELOPMENT AND MUSCLE DISEASE

Topic: 01. Muscle

Stephen J. Tapscott

Fred Hutchinson Cancer Research Center, Seattle, US

Abstract not received.

WS 2.2 / #152TRIALS READINESS IN FSHD: CLINICAL, IMAGING AND BIOMARKERS

Topic: 01. Muscle

Jeffrey M. Statland

Neurology, University of Kansas Medical Center, Kansas City, KS, US

Background: Facioscapulohumeral muscular dystrophy (FSHD) is one of the most common muscular dystrophies, and although it is slowly progressive, it can cause significant morbidity over the course of a lifetime, interfering with the ability to maintain a job or walk independently. There is at present no effective treatment for FSHD. Substantial evidence now implicates aberrant reactivation of DUX4 as the cause of FSHD providing a clear target for therapeutic intervention. The success in identifying the molecular and genetic mechanisms of FSHD provides a strong basis for drug development and therapeutic clinical trials. The key abnormality in FSHD, the aberrant expression of DUX4, is potentially amenable to RNA therapies making possible similar strategies to drugs already approved for spinal muscular atrophy and Duchenne muscular dystrophy, or may be amenable to other disease-directed strategies targeting epigenetic changes in FSHD. In addition, drugs not specifically targeting DUX4 but designed to ameliorate downstream pathology, such as muscle inflammation or muscle atrophy and fibrosis, are either underway now or proposed to start in the next few years. Methods: A prospective study of FSHD was performed in the 1990s that determined the multisite reliability and sensitivity to disease progression of manual muscle testing, quantitative myometry, and timed functional outcomes. However limitations to using strength or functional outcomes for FSHD were identified: the first is that the clinical relevance of relatively small changes in strength is unknown; and the second is that demonstrating arrest of disease progression would require large numbers of participants or long follow up times, creating a significant patient and financial burden. To best inform clinical trial design, it is now necessary to identify and validate measures of disease activity and progression. A conceptual framework for thinking about outcome development in FSHD is built on expert opinion about molecular pathology, disease progression, natural history studies, recent large MRI studies, and patient surveys and registries. It is likely we do not need a single outcome measure for FSHD but rather a clinical trial toolbox: in which clinical outcomes and biomarkers will play an important role. Results: Biomarkers can provide proof of concept a drug is reaching its target, can provide strategies to inform inclusion criteria or stratification, and can provide early signals of disease activity which will predict a later functional change. Here we will review the current state of biomarker development in FSHD, looking at the current experience with: 1) molecular biomarkers in muscle tissue; 2) serum biomarkers; 3) the use of MRI as a measure of disease progression, or for stratification; and 4) other techniques like electrical impedance myography or muscle ultrasound for tracking early changes in muscle quality. Conclusion: Development of robust FSHD-relevant biomarkers can hasten therapeutic development, and form a cornerstone of clinical trial preparedness.

WS 2.3 / #125FSHD’S CHANGING LANDSCAPE AND FUTURE PERSPECTIVES

Topic: 01. Muscle

George W. Padberg

Dep. Of Neurology, Radboud University Medical Center, Nijmegen, NL

Background: Facioscapulohumeral Dystrophy is an autosomal dominant disorder with a major myopathic phenotype and a variable, often incomplete minor phenotype. The myopathy has two components: an intrinsic muscle weakness, possibly congenital, on top of which develops a dystrophic proces with a specific descending sequence of muscle involvement which resembles a replay of embryological somite development. The age at onset and the rate of progression are extremely variable within and between families with FSHD and are used as measures of severity of the disease in individual cases. In earlier studies we estimated that 75% of the age at onset was related to environmental factors other than the primary gene defect. FSHD is caused by an epigenetic dysregulation of the D4Z4 macrosatellite repeat on 4q35 which leads to an aberrant expression of the Double-Homeobox gene Dux4 embedded in the terminal repeat unit. Dux4 can only be stably expressed if the repeat is followed by a PAS-sequence present in 4qA telomeric alleles to be found in 50% of the normal population. Dux4 is a double-homeodomain transcription factor normaly expressed in germ-cells and in the zygote-cleavage stage and repressed in later stages of development. Unknown at present is the rather basic question whether it has a function in myogenic stem-cells. The epigenetic repression of Dux4 has been related to the level of methylation proximal in the repeat. Hypomethylation is caused by a reduction of the number of repeats below 10 (FSHD1) or by mutations in SMCHD1 or DNMT3B (FSHD2), all leading to an identical muscle phenotype.The latter two are able to modulate FSHD1 as well. How the hypomethylation is established is presently under study but hypomethylation in itself appears not the only factor leading to Dux4 mRNA transcription. The upstream factors and modifyers of Dux4 expression and its downstream effects and pathways have to be evaluated for their risks and benefits in emerging therapies. Methods: Review of recent genetic and myo-biological literature in relationship to clinical features against the perspective of emerging therapies. Results: Knowledge of the epigenetic factors preventing Dux4 expression are invaluable for counselling (non-penetrance) and might lead to therapies. The downstream effects have to take into account the inflammatory response in muscles (possibly the onset of the dystrophic process), the distal to proximal fatty infiltration pattern as seen on MRI, the atrophic processes of the muscles, the early involved versus the relatively spared muscles and their genetic make-up and metabolic properties, the characteristic asymmetry of muscle involvement, possible gender differences and their metabolic background, and retinal vascular, cochlear, skeletal and possibly CNS involvement. Review of these aspects will lead to a translational research agenda. Conclusion: All the clinical aspects of the disease have to be explained before we fully understand the possible consequences of therapeutic interventions for this, probably most prevalent genetic risk factor for muscular dystrophy and at the same time indispensible gene for the primate lineage.

WS 3.1 / #123THE ROLE OF PALLIATIVE CARE €– EARLY INVOLVEMENT OR END OF LIFE CARE?

Topic: 12. Patient Issues

David J. Oliver

Tizard Centre, University of Kent, Canterbury, GB

Background: Palliative care is ”an approach that improves the quality of life of patients and their families facing problems associated with life-threatening illness, through the prevention and relief of suffering, early identification and impeccable assessment and treatment of pain and other problems, physical, psychosocial and spiritual”(WHO 2002). Thus within this definition the timing of palliative care involvement is open and should be related to the needs of the patient, and family, as assessed by an holistic assessment by a multidisciplinary team. Methods: A review of the literature was undertaken, together with clinical experience. Results: Although palliative care is often associated with care at the end of life the role is much greater. For a patient with progressive neuromuscular disease, such as ALS, it can be argued that the care should be palliative in it approach from the time of diagnosis. For instance the way the diagnosis is told to the patient and family can have significant effect on the later stages of care – a patient who understands that death may be distressing, from choking or breathlessness, may continue to fear these issues, despite any further discussion and explanation that these risks are small. The care of any patient with neuromuscular disease will need to include the multidisciplinary team assessment of all aspects of care: Physical – the symptoms and mobility issues Psychological – the fears and concerns of the person Social – most patients are part of wider families and have concerns for them or are the cause of concern to them Spiritual – the deeper issues that all people consider, particularly as they face progressive illness, of the meaning of illness and life Thus all professionals involved in the care of people with neuromuscular disease need to provide palliative care – aiming to maximize the quality of life of patients and families and listen and respond to the issues they face as individuals. This is usually from a multidisciplinary team, and may improve not only quality, but length, of life. Some patients and families will need increased care, from a specialist palliative care team because of very complex symptoms or psychosocial issues., perhaps at particular times – such as with the distress of diagnosis, consideration of gastrostomy, commencement of ventilatory support and at the end of life in ALS. At other times the care may be provided by the multidisciplinary team providing palliative care. Conclusion: Close collaboration and communication is essential among all the teams involved always responding to the individual patient’s needs. As the patient deteriorates and comes toward the end of life there may be increasing specialist palliative care, and hospice, involvement to support the patient, family, carers and professionals as death approaches. The care in the earlier stages will influence this time at the end of life and a careful team involvement, using specialist help as required, will allow patients and their families to approach death with confidence in their care and enable a less distressing terminal phase, and later bereavement for their family. Reference World Health Organization. Palliative care 2002 www.who.int/cancer/palliative/definition/en/

WS 3.2 / #110THE ROLE OF THE MULTIDISCIPLINARY TEAM IN NMD – THE EVIDENCE FROM ALS

Topic: 12. Patient Issues

Christopher Mcdermott

University Of Sheffield, Sheffield, US

Abstract not received.

WS 3.3 / #169THE RECOGNITION OF THE END OF LIFE PHASE IN NMD – THE SUPPORT OF PATIENTS, FAMILIES AND PROFESSIONALS

Topic: 12. Patient Issues

Stefan Lorenzl

Insitute of Nursing Science And Practice, Salzburg, DE

Abstract not received.

WS 3.4 / #854INTEGRATING PALLIATIVE CARE INTO SERVICE FOR ALS PATIENTS: REAL-LIFE EXPERIENCE

Topic: 12. Patient Issues

Lev Brylev¹, Vadim Parshikov², Yaroslava Krasnaya², Ekaterina Dikhter², Egor Larin³, Yana Batmanova², Vasiliy Shtabnitskiy⁴, Sergey Avdeykin⁵, Anastasia Ataulina⁵, Daria Puzanok², Anna Kasianova², Vera Fominyh¹, Margarita Fominyh², Maria Ivanova⁶, Elena Lysogorskaya⁶, Anna Vorobyeva⁶, Vera S. Demeshonok⁷, Tatiana Leontyeva², Timur Ivanov⁸, Maria Ilchenko², Alisa Apreleva⁹, Inessa Zakroyshikova⁶, Kirill Gorbachev¹, Artur Volov², Timur Mukhametov², Sergey Korneychuk², Natalia Semina⁸, Maria Zakharova⁶

¹Buyanov City Hospital, Moscow, RU;²ALS center Moscow, Moscow, RU;³Center of palliative medicine, Moscow, RU;⁴Chaika, Moscow, RU;⁵Buyanov city hospital, Moscow, RU;⁶Research center of neurology, Moscow, RU;⁷North-Western State Medical University named after I.I. Mechnikov, Saint Petersburg, RU;⁸Aprel clinic, Moscow, RU;⁹Anglia Ruskin University, Cambridge, GB

Background: The first specialized multidisciplinary outpatient center for ALS patients in Moscow started in 2012 and it is now a part of ENCALS network. The clinic follows about 200 families with ALS every year and is funded by charity foundation ”Live now”. Before 2012 patients with ALS had no access to palliative care, because hospices would not accept them and the national legislation which first mentioned the provision of palliative care for non-cancer patientswas only passed in 2011. Methods: Experience has shown that the main needs of patients and their caregivers are information, symptom management, and social and psychological support. To meet these needs palliative care has been gradually introduced into everyday practice. As we had no specialized education in palliative care for neurological patients in Russia, foreign experts were invited to teach our team and a palliative care physician, who studied palliative care abroad, was invited to the multidisciplinary discussions. Multidisciplinary outpatient consultations were started and the palliative care approach, with the emphasis on patient autonomy, dignity and quality of life, changed our practice completely. Results: Analyzing our data from 672 patients we found out that median disease duration was 1188 days (range 791-1787), the time from first symptom to diagnosis was 365 days (range 191 -587) and the time from diagnosis to referral to the team was 320 days (range 132 - 630) days. Patients on admission to our service had ALS for about 2 years and at this time the median vital capacity of 51% (range 38-80) and it was apparent that they had never talked about advance decision making and only 30% of them had ever talked to their families or physicians about prognosis and death. The training we received enhanced our communication skills and it was possible to talk with patients about prognosis and decisions about life sustaining interventions. This was particularly important if patient and families lack information and symptoms are inadequately controlled to prevent unwanted hospitalizations and prolonged ventilator support, that could affect quality of life. Moreover according to Russian legislation interventions, such as ventilation, cannot be withdrawn. One of the most prevalent end-of-life symptoms is dyspnea, -40% of our patients have persistent dyspnoea with median Borg score 5 out of 10. Dyspnoea is also one of the main reason for admission to Intensive care, especially where there has been limited discussion of the use of life sustaining interventions. We were the first team in Russia to use morphine for dyspnea in ALS patients. Our experience shows that morphine may be used safely, with evidence that there is no increase in pCO2 in arterial blood, and effectively – patients evaluated the response as good for 50%, partial for 40% and only 10% reported no help. Conclusion: There is continued close working between neurologists and palliative care specialists with the aim of integrating palliative care principles in standards of care for ALS patients. There are still many challenges on this way. The reported study was funded by ”Live now” charity foundation and RFBR according to the research project № 18-315-00228мол_–а

WS 4.1 / #33UPDATE ON HISTOPATHOLOGICAL FEATURES OF INFLAMMATORY MYOPATHIES

Topic: 01. Muscle

Anthony Amato

Dep. Of Neurology, Brigham and Women’s Hospital, Boston, US

Abstract: The major types of inflammatory myopathies (IM), including dermatomyositis (DM), polymyositis (PM), immune-mediated necrotizing myopathy (IMNM), antisynthetase syndrome (ASS), and inclusion body myositis (IBM) The characteristic histopathological abnormality on muscle biopsy in DM is perifasicular atrophy, however, this is present in perhaps only 50% of patients. Immunohistochemical staining for myxovirus resistance protein A (MxA) is diagnostically more sensitive and highly specific. The inflammatory cell infiltrate is predominantly perivascular and in the perimysium and is composed primarily of macrophages, B cells, and plasmacytoid dendritic cells (PDCs). PM is a heterogeneous disorder and muscle pathology is variable. Most often, CD8+ T cells and macrophages are evident in perimysial and endomysial locations. These mononuclear inflammatory cells surround fibers with sarcolemmal MHC-I expression, however true invasion of non-necrotic muscle fibers is much more common in IBM than in PM. The major subtypes of IMNM are anti-SRP and anti-HMGCR necrotizing myopathies, though some are paraneoplastic, associated with other connective tissue diseases, or are idiopathic. The hallmark on muscle biopsy are the presence of multifocal necrotic and regenerating muscle fibers with a paucity of inflammatory cells. However, some patients with HMGCR myopathy have endomysial, macrophage-predominant infiltrates similar to what is seen in PM. Overexpression of MHC-I and membrane attack complex (MAC) deposition in capillaries may be evident on sarcolemma of non-necrotic fibers. In ASS, muscle biopsies demonstrate a predilection for perimysial damage including perimysial fragmentation and staining with alkaline phosphatase, plasmacytoid dendritic cells and macrophages in the perimysium and around blood vessels, and MAC deposition on capillaries. Similar to DM there is perifascicular muscle fiber damage, but with AAS there is more perifascicular muscle fiber necrosis compared to DM, while in perifascicular atrophy is more prominent. MHC-1 and MAC deposits on muscle fibers may be seen on sarcolemma of perifascicular muscle fibers. EM may show actin filaments within myonuclei.

WS 4.2 / #101UPDATE ON MYOSITIS SPECIFIC AUTOANTIBODIES / DISCUSSION ON UTILITY OF MSAS IN DIAGNOSIS AND PROGNOSIS

Topic: 01. Muscle

Andrew Mammen

NIAMS/NIH, Bethesda, US

Abstract not received.

WS 4.3 / #115UPDATE ON UTILITY OF SKELETAL MUSCLE MRI AND ULTRASOUND

Topic: 01. Muscle

Jasper M. Morrow

Queen Square Centre For Neuromuscular Diseases, University College London, London, GB

Background: Recent advances in inherited muscle diseases have led to two major challenges. The development of next generation sequencing has made interpretation of genetic results very difficult; whilst the development of potentially effective gene therapies has emphasised the need for robust outcome measures to determine their efficacy. Qualitative and quantitative skeletal muscle imaging, in particular MRI is emerging as useful tools to address these challenges. Methods: The speaker will update recent literature on the topic, in addition to discussing his own research and clinical experience through illustrative case studies. Results: Pattern of muscle involvement on qualitative MRI or ultrasound has an important role in clinical phenotyping to help guide and interpret genetic testing in inherited muscle diseases; most notably in the congenital myopathies. Whilst most research has focussed on the lower limbs, whole body MRI is becoming more common. In acquired myopathies, MRI is useful in diagnosis, targeted biopsy and in aiding treatment decisions. The use of imaging in diagnosis will be illustrated through a number of clinical vignettes. Quantitative muscle MRI is able to measure both acute and chronic changes in skeletal muscle providing potential biomarkers in clinical trials. Fat-fraction quantification using methods such as three-point Dixon is the most robust marker of disease progression and has now been applied across a wide range of diseases in both natural history and interventional studies showing superior responsiveness to other outcome measures. Acute changes in muscle water distribution are sensitive to a number of quantitative techniques with T2 quantification being the most commonly used. Recent studies have shown that these changes are reversible with effective therapy, such as corticosteorids in Duchenne. Conclusion: Skeletal muscle MRI and ultrasound are rapidly becoming essential tools in neuromusuclar diseases. Potential avenues for furture research will be discussed.

WS 5.1 / #120DIAGNOSIS AND TREATMENT OF CIDP: LESSON FROM THE DATABASES

Topic: 02. Neuropathy

Eduardo Nobile-Orazio, Giuseppe Liberatore, Pietro Doneddu

Neuromuscular And Neuroimmunology Service, Humanitas Research Hospital, Milan University, Rozzano, Milan, IT

Background: Chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) is a chronic disabling disease that often improves with immune therapy. A few variants of CIDP have been described but their frequency and possible evolution into typical CIDP are unsettled, possibly because of differences in the diagnostic criteria and in the time of follow-up. To date, the most reliable diagnostic criteria for CIDP are the 2010 EFNS/PNS revised criteria, with a reported sensitivity of 80% and specificity of 90%. Methods: We implemented a web-based database to collect data from patients with CIDP followed by Italian Centers with expertise on CIDP to determine the frequency and characteristic of CIDP and it variants, the diagnostic criteria used for their diagnosis, the possible evolution into typical CIDP, the association with specific anti-nerve antibodies, and their response to therapy. All the patients were evaluated at the time of inclusion and will be followed for two years to monitor their outcome and response to therapy. Results: By February 2018 we enrolled 493 patients in the database, 41 of whom were excluded for the presence of an alternative diagnosis (23 patients) or insufficient data (18 patients). The diagnosis of typical CIDP was made in 368 (81%) of the 452 included patients with 305 (83%) fulfilling the EFNS/PNS criteria. Eighty-four patients (19%) patients had a diagnosis of atypical CIDP, 64 (76%) of whom fulfilled the EFNS/PNS criteria. Thirty-six of these patients (8% of included patients) had distal acquired demyelinating symmetric neuropathy (DADS), 17 (4%) purely motor CIDP, 17 (4%) Lewis-Sumner syndrome (LSS) including two with focal CIDP, 14 (3%) purely sensory including two with chronic immune sensory polyradiculopathy (CISP). Based on the symptoms ad disease onset and for at least one year, 39% of the patients had an initial diagnosis of atypical CIDP that had evolved into typical CIDP in more than 50% of the patients (53.5%) at the time of inclusion after a mean disease duration of 6.5 years. Improvement after therapy was observed in 87% of the 289 treated patients with typical CIDP including response to IVIg in 74% of the patients, steroids in 52%, plasma exchange in 53% and immune suppressant in 37% with Rituximab being the most frequently effective (70%). Patients with DADS and LSS had a less frequent response to therapy than those with typical CIDP (p=0.0006; p=0.0185), mainly reflecting a less frequent response to IVIg (p=0.0440; p=0.0136). Patients with pure motor and sensory CIDP did not differ from typical CIDP. In 63 patients the diagnosis of CIDP was not supported by nerve conduction studies according to the EFNS/PNS diagnostic criteria. In 74% of them there were however at least two supportive criteria for the diagnosis of CIDP including response to immune therapies (94%) and increased CSF proteins (82%). Similarly to typical CIDP, 50% of the patients with clinical CIDP had a relapsing course increasing the reliability of the diagnosis for CIDP. Conclusion: This study on a large population of patients is providing useful information that may help to revise the current diagnostic criteria for CIDP.

WS 5.2 / #93PARAPROTEINEMIC NEUROPATHIES: WHEN AND HOW TO TREAT

Topic: 02. Neuropathy

Jean-Marc Léger

National Referral Center For Neuromuscular Diseases, University Hospital Pitié-Salpêtrière, Paris, FR

Abstract: Since the first description 25 years ago of a high prevalence of monoclonal gammopathy (MG) in a context of peripheral neuropathy (PN), an increased number of such associations has been reported. However, neuropathies associated with MG have heterogeneous clinical, neurophysiological, neuropathological, and haematological features. The more pertinent relationship seems that found in distal acquired demyelinating sensory (DADS) neuropathy associated with IgM MG of unknown significance (MGUS), and the presence of serum auto-antibodies reacting with myelin-associated-glycoprotein (MAG). However in the absence of adequate data concerning relationship in most of cases, the following good practice points may be agreed: (1) Patients with demyelinating neuropathy (DNP) associated with MG should be investigated for a malignant plasma cell dyscrasia. The MG is more likely to be causing the neuropathy if it is IgM, autoantibodies (mainly directed to MAG) are present in serum or on nerve biopsy, or the clinical presentation is chronic distal sensory neuropathy. DNP associated with IgM MGUS sometimes responds to immune therapies. Their potential benefit should be balanced against their possible side-effects. Rituximab, an anti-CD 20 monoclonal antibody, seems a promising therapy. DNP associated with IgG or IgA MGUS is indistinguishable from chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), on clinical, electrophysiologic, and therapeutic issues. For POEMS (polyneuropathy, organomegaly, endocrinopathy, M-protein, skin changes) syndrome, suited therapy may be followed by dramatical improvement of the neuropathy. (2) Patients with chronic axonal polyneuropathy associated with IgG MG should be investigated for Al amyloidosis. However, the majority of chronic axonal polyneuropathies associated with IgG or IgM MGUS are indistinguishable from chronic idiopathic axonal polyneuropathies and do not need any treatment.

WS 5.3 / #107POEMS SYNDROME: FROM DIAGNOSIS TO THERAPY

Topic: 02. Neuropathy

Michelle Mauermann

Mayo Clinic, Rochester, MN, US

Background: Monoclonal gammopathies affect 3-4% of the population older than 50 years and affect more than 5% of the population older than 70 years. They reflect a diverse group of disorders that share the secretion a monoclonal Immunoglobulin produced by the bone marrow. POEMS syndrome is a rare paraneoplastic syndrome associated with a monoclonal plasma cell disorder. It frequently presents with a subacute sensorimotor peripheral neuropathy that can progress to a severe polyradiculoneuropathy. The diagnostic criteria for POEMS syndrome require the presence of a monoclonal plasma cell proliferative disorder and a polyneuropathy. Other major criteria include elevated vascular endothelial growth factor (VEGF), Castleman disease and sclerotic bone lesions. There are several minor criteria including organomegaly, extravascular volume overload, endocrinopathy, skin changes, papilledema and thrombocytosis/polycythemia. Methods: In this course we will review the challenges in making the diagnosis of POEMS syndrome. We will also review the clinical, electrophysiological and pathologic features of the peripheral neuropathy associated with POEMS syndrome. We will discuss the rationale behind the treatments available for POEMS syndrome and the future directions in therapy. Results: POEMS syndrome typically presents with a demyelinating sensorimotor peripheral neuropathy that progresses to a polyradiculoneuropathy. It is often mistaken for chronic inflammatory demyelinating polyneuropathy (CIDP). Distinguishing features include older age of onset, infrequent cranial nerve involvement, more severe distal lower extremity involvement and frequent pain. The electrophysiological features show uniform demyelination with less frequent conduction block and temporal dispersion. Recent studies have showed the utility of blink reflexes in demyelinating neuropathies and its utility in assessing treatment responses in POEMS syndrome. The monoclonal plasma cell disorder associated with POEMS syndrome is lambda light chain restricted in greater than 95 percent of patients. Radiologic evaluation for the presence of sclerotic bone lesions is recommended, with CT providing increased sensitivity over skeletal survey. Currently there is no approved treatment for POEMS syndrome. Radiation is used for patients with limited bone lesions without evidence of systemic disease. For patients with greater numbers of bone lesions or bone marrow involvement, systemic therapy is recommended. Autologous stem cell transplantation has been shown to be beneficial in the improvement of overall survival and progression free survival. Studies of also shown that the peripheral neuropathy improves after autologous stem cell transplantation. In patients ineligible for radiation therapy or autologous stem cell therapy other systemic therapies are available and have been shown to be efficacious. Conclusion: POEMS syndrome typically presents with a subacute painful demyelinating polyradiculoneuropathy. It is differentiated from other monoclonal protein associated disorders by the presence of a lambda monoclonal protein, demyelinating features on nerve conduction studies as well as systemic symptoms. It is important to consider this diagnosis in cases of treatment refractory CIDP. Early diagnosis is necessary to prevent worsening disability. There are several therapies shown to be beneficial in the treatment of POEMS syndrome but there is lack of comparison between these treatments.

WS 6.1 / #195ULTRASOUND IN CRANIAL NERVES

Topic: 07. Cranial Nerves

Stefan Meng

KFJ Hospital, Vienna, AT

Abstract not received.

WS 6.2 / #141CLINICAL AND MICROSURGICAL SIGNIFICANCE OF CRANIAL NERVE VISUALIZATION

Topic: 07. Cranial Nerves

Andres Rodriguez

Uppsala University, Uppsala, SE

Abstract not received.

WS 6.3 / #89HIGH RESOLUTION MRI OF CRANIAL NERVES

Topic: 07. Cranial Nerves

Jennifer Kollmer

Heidelberg University Hospital, Heidelberg, DE

Abstract not received.

WS 7.1 / #71CACHEXIA AND LATE EFFECTS OF CANCER (FROM AN ONCOLOGICAL PERSPECTIVE)

Topic: 08. Cancer

Ioannis Gioulbasanis

Chemotherapy, Larissa General Clinic ”E Patsides”, Larissa, GR

Background: Cancer cachexia is a syndrome characterized by progressive loss of weight and muscle wasting that eventually leads to functional decline and adversely affects survival. When fully developed, even patients themselves can easily recognize it, as it is associated with major changes in body image. However, a key prerequisite for a successful therapy is the timely initiation of any intervention - before the syndrome becomes irreversible. An important limitation, however, is that there are no specific symptoms, signs or laboratory tests that could trigger well-timed clinical attention and diagnosis. Methods: According to our current perception, there is a pre-cachectic stage characterized by anorexia and ”minor metabolic changes”. Anorexia, however, is a non-specific symptom that may be present in about half of cancer patients at diagnosis and could be attributed to a variety of causative factors that may or may not be related with the pathogenesis of the syndrome. When the syndrome is progressing, reduced food intake (the unavoidable consequence of persistence anorexia) will lead to decrease energy intake. Moreover, systemic inflammation, measured in practice by increased levels of C-reactive protein, is usually present and is associated with increased metabolic rate and energy consumption. These conditions result in negative caloric and protein balance and they can be routinely identified in the context of a detailed nutritional assessment. They also lead to depletion of fat and muscle stores quantified as weight loss >5% or >2% when either body mass index is <20kg/m² or sarcopenia is present. Patients at this stage of cachexia may frequently experience fatigue, a symptom causally related to cachexia and, together with anorexia, they composed one of the most prevalent symptom clusters. Results: In the last (refractory) phase, the most characteristic feature is the deterioration of the performance status and patients commonly suffer from asthenia (a subjective sensation of tiredness without any effort) and/or depression. Moreover, because the tumor is no longer responsive to anticancer treatment, many of them experience uncontrolled symptoms like pain and dyspnea and their quality of life deteriorates further. Conclusion: While these aforementioned phases of the syndrome usually cannot be clearly distinguished from one another, most patients with advanced cancer with ultimately develop cachexia.

WS 7.2 / #130SARCOPENIA

Topic: 08. Cancer

Alan Pestronk

Washington University School of Medicine, Neuromuscular Clinic, St. Louis, US

Abstract not received.

WS 7.3 / #30OUTLINE ON MYOPATHIES / NEUROMUSCULAR COMPLICATIONS ASSOCIATED WITH CANCER, INCL. STEROID MYOPATHY

Topic: 08. Cancer

Anthony Amato

Dep. Of Neurology, Brigham and Women’s Hospital, Boston, US

Abstract: Weakness in patients with cancer is often multifactorial. Most common etiology is sarcopenia related to cachexia and disuse. Corticosteroids used to treat edema (brain tumors) can cause type 2 muscle fiber atrophy leading to weakness as well. Dermatomyositis, polymyositis, and autoimmune necrotizing myopathy as well as Lambert-Eaton myasthenic syndrome can be paraneoplastic and these disorders be the presenting manifestation. Check-point inhibitors have recently been shown to be associated with autoimmune myopathies and neuropathies. Only rarely have chemotherapies been associated with a direct toxic effect on muscle.

WS 7.4 / #103CANCER REHABILITATION

Topic: 08. Cancer

Christine Marosi

Medical University of Vienna, Vienna, AT

Abstract not received.

WS 8.1 / #118SPECTRUM OF PARAPROTEINEMIC NEUROPATHIES

Topic: 02. Neuropathy

Eduardo Nobile-Orazio

Neuromuscular And Neuroimmunology Service, Humanitas Research Hospital, Milan University, Rozzano, Milan, IT

Background: A consistent proportion patients with neuropathy have a monoclonal gammopathy (or paraprotein) in their serum suggesting a possible pathogenetic link between the two abnormalities. In a series from an highly specialized Center for the diagnosis of neuropathy in the United States, 4% of patients with neuropathy had a monoclonal gammopathy being the third leading cause of neuropathy after diabetes (31%) and genetic disease (7%). A similarly high frequency was observed in an unselected series of patients with neuropathy from Sweden where monoclonal gammopathy was only less frequent than diabetes (19%), genetic diseases (12%), alcohol (10%), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP) (8%) other toxic neuropathies (6%) and connective tissue disorders (5%). On the other hand monoclonal gammopathy is frequent in the adult population being found in 3% of the popula­tion above 50 years of age and 7.5% above 85 years indicating that a coincidental association may also frequently occur. It is therefore important for the neurologist to clarify the pathogenetic significance of this association since the neuropathy may occur in patients with an otherwise asymptomatic monoclonal gammopathy not requiring for the hematologist any treatment. Methods: Neuropathy has been associated with several diseases characterized by the presence of a monoclonal gammopathy being reported in 3-14% of patients with multiple myeloma, 30-50% of those with Waldenström’s macroglobulinemia (WM), 2-8% with Lymphoma, and 10-20% with light chain amyloidosis (AL). In these conditions the treatment is mainly addressed by the hematologist while neurologist are mainly involved in the initial diagnosis, since neuropathy may be the presenting symptom, or in assessing the possible occurrence of neuropathy induced by the chemotherapy used for the hematological disorder. More relevant for the neurologist is the occurrence of neuropathy in patients with monoclonal gammopathy of undetermined significance (MGUS), where the prevalence of symptomatic neuropathy range form 8% to 36%. In all these studies the prevalence of neuropathy is higher in patients with IgM than with IgG or IgA MGUS, indicating that IgM monoclonal gammopathy are more likely to have a pathogenetic role in the neuropathy. This is also supported by the frequent occurrence of IgM antibodies against nerve antigens in patients with IgM monoclonal gammopathy that may be found in over 50% of the patients with neuropathy. Results: An additional condition presenting to the neurologist is the POEMS syndrome, a rare multisystem disease characterized by the presence polyneuropathy (P), organomegaly (O), endocrinopathy (E), monoclonal gammopathy (M) and skin changes (S). The pathogenesis of POEMS syndrome is poorly understood but overproduction of vascular endothelial growth factor (VEGF) is considered to play a major role. A severe neuropathy with electrophysiological signs of both axonal and myelin involvement is the predominant manifestation of this syndrome and requires aggressive therapy to prevent a disabling clinical course. Conclusion: We will address in this lecture the therapy used by the neurologist in the treatment of these neuropathies and only briefly mention the therapies used by the hematologist to treat the malignant forms of monoclonal gammopathy.

WS 8.2 / #153ANTI-MAG NEUROPATHY: CURRENT AND NOVEL TREATMENTS

Topic: 02. Neuropathy

Andreas Steck

Department Neurology, Basel, CH

Abstract: Anti-MAG (myelin-associated glycoprotein) neuropathy is a chronic disabling demyelinating peripheral neuropathy with an autoimmune etiology. Anti-MAG antibodies are detected in half of IgM paraproteinaemic neuropathy cases. Monoclonal IgM autoantibodies recognize the HNK-1 trisaccharide epitope that is present on MAG as well as on other glycoconjugates of the peripheral nervous system. Electrodiagnostic tests reveal a distal demyelinating polyneuropathy with marked prolonged distal motor latencies. Nerve biopsy shows demyelinating characteristics with pathognomonic features: IgM deposits in the myelin sheaths and widening of myelin lamellae. Anti-MAG antibodies are detected by ELISA. The goal of current therapies is the reduction of pathogenic autoantibodies, the decrease of expanded autoantibody-producing B cell clones, and/or the interference with antibody-effector mechanisms. We will review current and novel treatments. Cytostatics (e.g. cyclophosphamide), plasma exchange (for acute worsening), intravenous immunoglobulin, and the CD20+ B cell-depleting agent Rituximab have been used for the therapy of anti-MAG neuropathy. New anti- B cells drugs such as Ofatumumab, Ocrelizumab, Obinutuzumab and Ibrutinib have been proposed. However, these approaches lack selectivity, and thus so far no satisfactory treatment is available. Because clinical improvement of patients’ neuropathic symptoms correlates with reduced serum levels of anti-MAG antibodies and disease worsening is associated with increasing anti-MAG levels during treatment follow-up, a more efficient and safe therapy might be achieved with antigen-specific agents that selectively target anti-MAG IgM antibodies or antibody-producing B cells. We will present data showing that a synthetic glycomimetic of the natural HNK-1 glycoepitope efficiently remove pathogenic anti-MAG antibodies in an immunological mouse model for anti-MAG neuropathy thus opening a new avenue for treatment. References: Herrendorff R. et al. Selective in vivo removal of pathogenic anti-MAG autoantibodies, an antigen-specific treatment option for anti-MAG neuropathy. Proc Natl Acad Sci U S A. 2017;114(18):E3689-E3698 Pruppers M.H.J. et al. Improving future assessment and research in IgM anti-MAG peripheral neuropathy: A consensus collaborative effort. Neuromuscular Disorders 27 (2017) 1065–1072

WS 8.3 / #111CREATING PROPER OUTCOME MEASURES

Topic: 02. Neuropathy

Ingemar Merkies

Department Of Neurology, Maastricht University Medical Center, Maastricht, NL

Abstract not received.

WS 9.1 / #56NERVE FIBRE TRANSFER VERSUS NERVE RECONSTRUCTION

Topic: 06. Mononeuropathy

Robert Schmidhammer

Ludwig Boltzmann Institute for Experimental and Clinical Traumatology, Vienna, AT

Abstract not received.

WS 9.2 / #81NERVE REGENERATION

Topic: 06. Mononeuropathy

Ahmet Hoke

Johns Hopkins University School of Medicine, Baltimore, US

Abstract not received.

WS 9.3 / #179BRAIN PLASTICITY IN NERVE REGENERATION

Topic: 06. Mononeuropathy

Thomas Hausner

Trauma Surgery, Lorenz Böhler Trauma Hospital, Vienna, AT

Background: Injuries to the peripheral nervous system induces reorganization of the projections to the Central Nervous System (CNS). This reorganization occurs in the cortex and in different other levels of the CNS, such as the thalamus, brainstem relay nuclei, and spinal cord. In general, this reorganization is referred to as cerebral plasticity or as brain plasticity.Injuries to the peripheral nervous system induces reorganization of the projections to the Central Nervous System (CNS). This reorganization occurs in the cortex and in different other levels of the CNS, such as the thalamus, brainstem relay nuclei, and spinal cord. In general, this reorganization is referred to as cerebral plasticity or as brain plasticity. Methods: Functional recovery after nerve injury and repair relates to the plastic changes in the CNS. The reorganization of the cortex and subcortical structures occur very rapid and therefore influence the outcome of a peripheral nerve repair. To provide cortical reorganization different methods based on the phenomenon of transmodality - converging of a unimodal sensoric input to multimodal association areas of the cortex - have been established. Results: Rosen and Lundborg in 2007 published the ”Sensor Glove System” which mediates impulses to the somatosensory cortex through the hearing sense initiated early after surgery. Schmidhammer and his group also in 2007 extended the sensoric input by using both the hearing and the optical sense starting the treatment the day after surgery. The same group could demonstrate recovery of primary activation of the affected hemisphere in a longitudinal functional magnetic resonance imaging (fMRI) observation of cortical somatosensory reorganization. Conclusion: The use of brain plasticity thus is one part of the complex treatment strategies in the repair and rehabilitation after peripheral nerve injuries. The author will give a review of the literature and report clinical experience and results in this field.

WS 10.1 / #183HOW TRANSTHYRETIN BECOMES TOXIC

Topic: 02. Neuropathy

Laura Obici

Fondazione IRCCS Policlinico San Matteo, Pavia, IT

Abstract not received.

WS 10.2 / #198CHALLENGES IN DIAGNOSING AND MONITORING ATTR AMYLOIDOSIS

Topic: 02. Neuropathy

Davide Pareyson

Dept Of Clinical Neurosciences, IRCCS Foundation, C.Besta Neurological Institute, Milan, IT

Abstract: Inherited transthyretin amyloidosis (ATTR) has become a treatable disorder with effective therapies available. Early diagnosis is therefore fundamental for preventing progression in this disease, lethal if left untreated. Diagnosis is easier in familial cases in endemic regions, where Val30Met is the most frequent mutation, degree of awareness is high, and presentation is typical, with a predominantly small-fibre length-dependent sensory neuropathy with dysautonomia, only later involving motor fibres. On the other hand, diagnosis is often delayed in non-endemic region where the neuropathy occurs late in life, the spectrum of mutations is much wider, family history if often negative or misleading, signs of dysautonomia are subtle, presentation is atypical with a sensory-motor polyneuropathy involving all fibre types, and progression is faster. High degree of clinical suspicion, careful investigation of neuropathy features, of early autonomic manifestations, of carpal tunnel syndrome, and of cardiac, ocular or renal involvement allow prompt identification of the disease and early treatment. Careful monitoring of presymptomatic mutation carriers permits early detection of the first symptomatic phases of the disease. Systematic and homogenous follow up of treated patients, with common core protocols, will allow the collection of data useful to optimize treatment and select the best therapeutic options according to disease type and stage. Improvement of clinical and paraclinical outcome measures is a challenging task. The currently used types of Neuropathy Impairment Score (NIS) scores should be unified and simplified. Linear scales should be designed. Glomerular filtration rate (GFR) seems to be a reliable biomarker for disease staging and possibly for monitoring disease evolution, to be added to Brain Natriuretic Peptide (BNP) as a marker of cardiac disease. mBMI is another important parameter easy to calculate. Standardized nerve conduction studies, nerve echography, nerve MRI, skin biopsy, echocardiography, cardiac scintigraphy, cardiac MRI, autonomic function tests are all important tools for diagnosis and monitoring disease course during treatment.

WS 10.3 / #194THE NOVEL SCENARIO OF ATTR AMYLOIDOSIS TREATMENT

Topic: 02. Neuropathy

Teresa Coelho

Hospital de Santo Antonio, Porto, PT

Abstract not received.

WS 11.1 / #918VITAMIN DEFICIENCIES AND NEUROPATHY

Topic: 09. Systemic Diseases

Carrie K. Grouse

Neurology, University of California San Francisco, San Francisco, US

Background: Vitamin deficiencies may result in neurologic deficits, including neuropathy. Methods: Review of published literature on the topic of vitamin deficiencies and neuropathy. Results: Vitamin B12 (cobalamin), B1 (thiamine), B6 (pyridoxine), and vitamin E (alpha-tocopherol) are all essential vitamins that can become deficient, causing a peripheral neuropathy. Conclusion: It is important for neurologists to recognize the role of vitamin deficiencies in causing treatable sensory and motor neuropathies.

WS 11.2 / #217MINERAL DEFICIENCIES AND NEUROPATHY

Topic: 09. Systemic Diseases

Steven L. Lewis

Neurology, Lehigh Valley Health Network, ALLENTOWN, PA, US

Background: Mineral deficiencies may result in various neurologic manifestations including neuropathy. Methods: Review of published literature on the topic of mineral deficiencies and neuropathy. Results: Copper deficiency may cause a primarily sensory axonal polyneuropathy in addition to a myelopathy; optic neuropathy can also occur. Hypophosphatemia, occurring due to intravenous hyperalimentation without inorganic phosphate, has been associated with an acute sensorimotor polyneuropathy resembling Guillain–Barre syndrome. Molybdenum deficiency has been reported to be associated with a motor neuron disorder in sheep. Conclusion: Although less common than vitamin deficiencies as a cause of neuropathy, it is important for neurologists to recognize the role of some mineral deficiencies in causing treatable peripheral and optic neuropathies.

WS 11.3 / #223VITAMIN AND MINERAL TOXICITIES AND NEUROPATHY

Topic: 09. Systemic Diseases

Nathan Staff

Neurology, Mayo Clinic, Rochester, MN, US

Background: Peripheral nerves are uniquely susceptible to a variety of toxic insults, which is likely attributable to the metabolic demands on these neurons that span up to 1 meter in length. Peripheral neuropathy due to vitamin and mineral toxicities has been reported due a number of environmental, medicinal, and industrial exposures. While advances in public and occupational health have rendered many of these causes as very rare, these important and preventable etiologies may be overlooked in clinical practice if not considered in the differential diagnosis of peripheral neuropathy. Methods: Literature review was performed. Results: While most vitamins lead to neurological disease due to their deficiency, vitamin B6 leads to neurotoxicity from overuse and presents as a sensory-predominant axonal neuropathy or neuronopathy. Neurotoxicity from heavy metals arises from exposure to lead, mercury, inorganic arsenic, or thallium. Heavy metal neurotoxicity often has multisystem involvement, including abnormalities in the central nervous system (lead, mercury), integument (lead, arsenic, thallium), or gastrointestinal system (lead, arsenic, thallium). The peripheral neuropathy in heavy metal intoxication is variable and may range from motor-predominant (lead), sensory-predominant (mercury, arsenic, thallium), or polyradiculoneuropathy (arsenic, thallium). Treatment for heavy metal intoxication includes removal of exposure and chelation. Conclusion: Peripheral neuropathy due to vitamin and mineral toxicities continues to be a rare, but important cause of peripheral neuropathy. Oftentimes, these toxic neuropathies occur in the setting of multisystem disease, which may be a clue to the etiology. Furthermore, understanding the pathomechanisms of these rare neuropathies can provide important insights more broadly into peripheral nerve biology.

WS 12.1 / #165MULTIDISCIPLINARY CLINICS- WHAT IS THE EVIDENCE AND HOW CAN WE DO BETTER?

Topic: 03. Motor Neurone

Leonard Van Den Berg

Department Of Neurology, University Medical Center Utrecht, Utrecht, NL

Abstract not received.

WS 12.2 / #77MEASUREMENT OF DISEASE PROGRESSION, CAN WE DO BETTER?

Topic: 03. Motor Neurone

Orla Hardiman

Trinity College Dublin, Dublin, IE

Abstract not received.

WS 12.3 / #113REHABILITATION INTERVENTIONS THAT CHANGE OUTCOME IN ALS/MND

Topic: 03. Motor Neurone

Presenter TBD

WS 13.1 / #1030CRANIAL NERVES

Topic: 08. Cancer

Wolfgang Grisold¹, Anna Grisold², Stefan Meng³

¹Ludwig Boltzmann Institute for Experimental und Clinical Traumatology, Vienna, AT;²Dep. Neurology, Allgemeines Krankenhaus Vienna, Vienna, AT;³Institute for Radiology, KFJ hospital, Vienna, AT

Abstract: In cancer patients the cranial nerves (CN) can be affected by several mechanisms as infections, therapy related, and neoplastic. They can present as singular, or multiple lesions. Infections: Herpes Zoster is the most prominent infection in immune compromised patients. Usually the trigeminal nerve is involved resulting in sensory loss and pain. In caudal CN lesions local mucosatoxic effects need to be excluded. Therapy related effects can be classified into radiotherapy (RT) induced damage, damage by surgical interventions and embolization and a spectrum of chemotherapy induced effects as dysgeusia, which is prominent for hedgehog pathway inhibitors. Motor dysfunction is rare, but has been observed in vinka alkaloids. Neoplastic involvement within the skull is often caused by neoplastic CSF involvement, but also focal tumor seeding. Metastases at the base of the skull, and also in the major cavities present with pain in combination with CN lesions. Also skin tumor may spread retrogradely into the CNS. A very important model for CN lesions is the neoplastic spread via CN, either antero- or retrogradely. This mechanism is most frequently observed in ENT tumors. In addition to clinical neurological examination imaging techniques are the most useful tool to determine the site and cause of the CN lesions. For the extracranial parts of the CN, increasingly High frequency ultrasound is useful.

WS 13.2 / #64PERIPHERAL NERVE LYMPHOMA

Topic: 08. Cancer

P. James B. Dyck

Mayo Clinic, Rochester, US

Background: Lymphoma can involve almost any organ in the body including the nervous system. Neurolymphomatosis (NL) is a rare presentation of lymphoma involving the peripheral nerves. NL can be subdivided into those patients in whom the lymphoma began in the peripheral nervous system (primary NL) and those in whom it began in another organ system but spread to peripheral nerves (secondary NL). Methods: We have studied NL in terms of clinical, electrophysiological, radiographical and pathological features in a cohort of Mayo Clinic patients with NL proven by nerve biopsy. Results: We identified 48 NL patients (28 primary and 20 secondary). The most common presentations were asymmetric, painful radiculoplexus neuropathy (37.5%), polyradiculoneuropathy (23%) and multiple or single mononeuropathy (18%). Primary and secondary NL present similarly with primary NL having longer symptoms duration (10 vs. 6 months, p<0.001), single disease episodes (96% vs. 35%, p<0.001), more disease remission (58% vs. 20%, p=0.056) and lower rates of mortality (25% vs 67%, p=0.054). 11 of the 42 patients had electrophysiology showing demyelination. Nerve biopsies diagnostic of lymphoma were distal cutaneous (sural 9/11) or proximal targeted fascicular (35/35) nerves. MRI was better identifying lymphoma than CT or PET (84% vs. 46% vs. 58%). The lymphoma types were B-cell (46/48) and rarely T-cell (2/48) with diffuse large B-cell most common. Teased fiber showed increased rates of demyelination (19/24), increased rates of axonal degeneration (18/24) and increased numbers of empty nerve strands (9/24). The location of nerve lymphoma within the nerve was most commonly in the endoneurium (43/48), followed by epineurial (29/33). Clinical and pathological findings of primary and secondary NL were similar except secondary NL had a shorter duration of neuropathic symptoms (8.5 vs 4.5 months, p=0.01), more frequent other organ involvement (p=0.045), more axonal degeneration (31% vs. 7%, p=0.005), less favourable response to treatment and a higher mortality rate. Conclusion: 1) peripheral nerve lymphoma (NL) is a multifocal painful neuropathy that causes endoneurial inflammatory demyelination; 2) primary NL presents as a single episode whereas secondary NL often presents after remission of the lymphoma. These findings suggest that the nerve may act as a ”safe-haven” for NL as most chemotherapeutic agents don’t cross the blood nerve barrier and 3) primary NL is less severe with longer duration, less axonal degeneration, more favourable response to treatment and higher survival rates.

WS 13.3 / #270CANCER-ASSOCIATED MYOSITIS

Topic: 08. Cancer

Yves Allenbach

Department Of Internal Medicine And Clinical Immunology, APHP Pitié-Salpêtrière Hospital, Paris, FR

Abstract not received.

WS 14.1 / #143MOLECULAR MECHANISMS AFFECTING NEUROMUSCULAR JUNCTION DEVELOPMENT AND MAINTENANCE

Topic: 04. Neuromuscular Junction

Markus Rüegg

University Of Basel, Basel, CH

Abstract not received.

WS 14.2 / #193SALBUTAMOL AND DOK-7 AS POTENTIAL TREATMENT OPTIONS FOR NEUROMUSCULAR DISORDERS

Topic: 04. Neuromuscular Junction

David Beeson

Nuffield Department Of Clinical Neurosciences, University of Oxford, Oxford, GB

Abstract not received.

WS 14.3 / #142SYMPATHETIC INNERVATION OF THE NMJ; A POSSIBLE EXPLANATION FOR THE THERAPEUTIC EFFECT OF SYMPATHICOMIMETICS IN NMDS?

Topic: 04. Neuromuscular Junction

Rüdiger Rudolf

Institute Of Molecular And Cell Biology, Mannheim University of Applied Sciences, Mannheim, DE

Background: Recently, sympathicomimetic drugs, such as albuterol or salbutamol, have been increasingly used to treat a wide range of congenital myasthenic syndromes. However, the rationale underlying the effectiveness of these drugs has remained elusive. Methods: The distribution of sympathetic neurons in skeletal muscle was investigated with immunofluorescence and confocal microscopy. Functional interaction between sympathetic neurons and skeletal muscle was investigated by combined electrical stimulation of sympathetic ganglia and in vivo two-photon microscopy. Effects of local chemical sympathectomy or congenital myasthenic syndrome on muscle atrophy and NMJ function and morphology as well as their rescue by systemic treatment with sympathicomimetics, were probed using in vivo confocal microscopy and measurement of compound muscle action potentials. Results: We found that sympathetic neurons form a dense network in skeletal muscle already in the newborn mouse and make close contact with neuromuscular junctions. Functionally, they seem to connect different targets including blood vessels, motor neurons, and muscle fibers. Electric stimulation of sympathetic neurons triggered immediate activation of muscle postsynaptic ß2-adrenoreceptor (ADRB2), cAMP production, and nuclear import of PGC1alpha. Systemic treatment with the sympathicomimetic clenbuterol rescued electrophysiological and morphological defects of neuromuscular junctions as well as muscle atrophy upon local chemical sympathectomy and in myasthenic mice. Conclusion: In summary, this work shows intense sympathetic innervation of skeletal muscle that plays functions beyond the control of blood flow. Indeed, it appears to be of fundamental importance for muscle trophism and regulates the functionality and maintenance of neuromuscular junctions. Sympathetic innervation of skeletal muscle could be a link to the understanding of the therapeutic effects of sympathicomimetics in congenital myasthenic syndromes.

WS 15.1 / #178PLECTIN: OVERVIEW AND LESSONS FROM MOUSE MODELS

Topic: 01. Muscle

Gerhard Wiche

Biochemistry And Cell Biology, University of Vienna - MFPL, Vienna, AT

Background: Plectin is the prototype of a family of proteins known as cytolinkers, or cytoskeletal linker proteins. Mainly associating with intermediate filaments (IFs) and acting as a cytoskeletal crosslinker, plectin strengthens cells mechanically. Plectin’s large size of >500 kDa, multi-modular surface structure, and oligomerization potential enable it to undergo a broad spectrum protein-protein interactions that dic­tate its spatial localization, regulate cellular dynamics, and create cytoskeleton based signaling scaffolds. Plectin binds not only to all types of IFs, the actomyosin network system, and microtubules, but also to transmembrane receptors, proteins of the subplasma membrane protein skeleton, components of the nuclear and mitochondrial envelopes, and signaling proteins such as kinases with key roles in migration, proliferation, and energy metabolism of cells. Due to alternative splicing, plectin is expressed as multiple isoforms bearing distinct N-terminal head domains that dictate the differential subcellular targeting of the isoforms. Through specific interactions with proteins at their target sites and their high-affinity bind­ing to IFs of all types, distinct plectin isoforms provide site-specific and robust IF-docking sites. Plectin isoforms are thus central to IF network organization, compartmentalization, and connectivity. In fact, the functional repertoire of IF networks in different cell types is largely dependent on the type and ex­pression levels of individual plectin isoforms. IF anchorage has profound effects on the cytoplasmic microenvironment, including the redirection of actomyosin-driven forces and the repression of microtu­bule networks. Moreover, plectin isoform-mediated linkage of peripheral junctional complexes, interior organelles, and specialized cellular machineries (e.g. the contractile apparatus of muscle cells) to the IF network creates a tension-sensitive communication system which is key to mechanotransduction. Methods: To decipher plectin’s diverse functions and role in disease, we have generated a large collection of genetically altered mouse lines, comprising full-knockouts (null-KOs), tissue/cell type-restricted condi­tional-KOs, isoform-specific KOs, double-KOs, and knock-ins. This unique assemblage of mouse models serves as a powerful tool for studying consequences of plectin gene defects on the organismal, cellular, and molecular levels. Results: As constituent and interaction partner of vital cellular elements, dysfunctional plectin leads to multiple disorders and diseases, some of which are multi-systemic, i.e. affecting more than one tissue and cell type. The most common disease caused by plectin deficiency is epidermolysis bullosa simplex (EBS)-MD, an autosomal-recessive skin blistering disorder with late-onset muscular dystrophy. Other subtypes of EBS, EBS-PA and EBS-Mys, manifest with pyloric atresia and congenital myasthenia, respectively, and a dominant subtype, EBS-Ogna, results in a skin-only phenotype. Mutations in isoform-specific sequences of the plectin gene can cause either muscular dystrophy without skin phenotype, or skin blistering without muscular phenotype, in accordance with the isoforms’ specific functions. Conclusion: The analysis of mouse mutants revealed plectin to play an essential role in maintain­ing the integrity of the neuromuscular system, including the contractile apparatus of myofibers, the neuromuscular synapse, myonuclei and mitochondrial networks, as well as motor neuron and Schwann cell dependent functions. Furthermore, the role and pathomechanisms involving individual isoforms could be dissected and advances were made towards the development of treatment and therapeutic strategies of muscle-related plectinopathies using mutant mice-derived immortalized cell cultures.

WS 15.2 / #184HUMAN PLECTIN AND CLINICAL ASPECTS

Topic: 01. Muscle

Rolf Schröder

Neuropathology, University Hospital Erlangen, Erlangen, DE

Background: Plectin, a multi-functional linker protein of exceptionally large size (> 500kDa), is abundantly expressed in a wide range of mammalian cells and tissues, most prominently in muscle, brain and stratified squamous epithelia. Mutations in the human plectin gene (PLEC) on chromosome 8q24 cause a variety of rare human disorders (referred to as ”plectinopathies”), namely autosomal recessive epidermolysis bullosa simplex with muscular dystrophy (EBS-MD), EBS-MD with myasthenic features (EBS-MD-MyS), limb girdle muscular dystrophy (LGMD) type 2Q (LGMD2Q), EBS with pyloric atresia (EBS-PA), and the autosomal dominant variant EBS-Ogna. Methods: Clinical, genetic, myopathological and biochemical analyses of patients with plectinopathies. Results: In addition to an overview on the broad spectrum of clinical presentations of plectinopathies, this lecture will focus on the essential features of plectin-related human skeletal muscle pathology. Furthermore, recent ­advances in our current understanding of the molecular pathogenesis of human plectinopathies will be discussed in relation to future targeted treatment concepts. Conclusion: Plectin has an essential role for the structural and functional integrity of human skeletal muscle tissue. To date, mutations in the plectin gene account for three distinct forms of human myopathies. Given the recent advances of next generation sequencing approaches, more plectin-related myopathies and cardiomyopathies are likely to be discovered.

WS 15.3 / #191PLECTIN AND MITOCHONDRIA (MICE AND MEN)

Topic: 01. Muscle

Lilli Winter

Center For Anatomy And Cell Biology, Medical University of Vienna, Vienna, AT

Background: Plectin, a 500-kDA multifunctional cytolinker protein, interlinks intermediate filaments (IFs) with each other and anchors them to sites of strategic importance for the organization and function of cells. Plectin’s versatility is in part due to complex splicing events in the N-terminal region of its gene (PLEC), giving rise to a multitude of alternatively spliced isoforms containing different first exons. In skeletal muscle, plectin is essential for myofiber integrity and function: by specifically targeting and anchoring desmin IFs to Z-disks (plectin 1d, P1d), costameres (P1f), mitochondria (P1b), and the nuclear/ER membrane system (P1), the muscle-specific set of plectin isoforms determines the cytoarchitecture of the IF network and thereby ensures the precise alignment of sarcomers. Accordingly, mutations in the human plectin gene cause epidermolysis bullosa simplex with muscular dystrophy (EBS-MD), an autosomal recessive skin blistering disorder associated with progressive muscle weakness. In addition, PLEC mutations lead to EBS-MD with myasthenic syndrome, EBS with pyloric atresia, limb-girdle muscular dystrophy type 2Q, or EBS-Ogna. With skeletal muscles harboring desmin-positive protein aggregates, degenerative changes of the myofibrillar apparatus, and mitochondrial abnormalities, most plectinopathies can be annotated among the expanding group of myofibrillar myopathies (MFM). All MFM show a progressive clinical course, lead to severe physical disability and premature death. The knowledge of the precise molecular mechanisms that translate MFM-causing gene mutations into the myopathic phenotype is still limited, but critical for the understanding of patients’ needs and the development of treatments. Methods: To assess the mitochondrial pathology of plectinopathy patients, skeletal muscle tissues derived from three EBS-MD patients were analyzed for mitochondrial abnormalities, including altered subcellular localization and expression of respiratory chain enzymes. In addition, to better understand the mechanisms behind mitochondrial defects in plectinopathies and to dissect the role of individual plectin isoforms, we comparatively analyzed morphological and functional characteristics of mitochondrial networks in skeletal muscle tissues and teased muscle fibers derived from wild-type, muscle-specific conditional plectin knockout (MCK-Cre/cKO), and plectin-isoform-specific knockout mice, lacking just one isoform (either P1b or P1d) while expressing all others. Results: In muscle sections from EBS-MD patients and plectin-deficient mice, mitochondrial content appeared reduced. Mitochondria were abnormally distributed within muscle fibers, aggregated, and no longer associated with the Z-disks. Mitochondrial clusters were observed in sarcoplasmic and subsarcolemmal regions. Additionally, decreased citrate synthase activity, decreased mitochondrial respiratory functions, and altered ADP kinetics were detected in plectin-deficient mouse muscles. By comparing mitochondrial networks in muscle sections and teased muscle fibers derived from isoform P1b or P1d-specific knock-out mice, we found plectin-isoform-dependent morphological alterations of mitochondria. In P1d-KO muscle, where Z-disks appeared misaligned, mitochondria lost their regular cross-striated staining pattern, but remained in close contact to the Z-disks. In contrast, mitochondria in P1b-KO muscle were more elongated and loosely arranged around the Z-disks; however, no Z-disk misalignment occurred in this case. Conclusion: Plectin (isoform) mutations dramatically affect the subcellular distribution and biochemical properties of mitochondria in men and mice. The depletion of distinct plectin isoforms affected mitochondrial network organization in different ways.

WS 15.4 / #192PLECTIN, CARDIOMYOPATHIES, AND THERAPEUTIC APPROACHES (MICE)

Topic: 01. Muscle

Oliver Mueller

University Of Kiel, Kiel, DE

Abstract not received.

WS 16.1 / #292THE CLINICAL PHENOTYPES OF CALPAINOPATHY

Topic: 01. Muscle

Andoni Urtizberea

Aphp - Filnemus, Hendaye, FR

Abstract: Primary calpain deficiency, or LGMD2A, is characterized by a selective, slowly progressive involvement of proximal muscles of pelvic and scapular girdles. In most LGMD2A patients, the typical overall picture corresponds to the clinical phenotype originally described by W. Erb in 1884 and revisited by M. Fardeau in the 1980s in a genetic isolate of patients living in the Reunion Island. The onset of weakness occurs in the early teens, in most cases in the lower limbs rather than in the upper limbs. Difficulties in running or in climbing stairs, tiptoe walking and scapular winging are classical symptoms/signs at presentation. Marked contractures in elbows or ankles, and muscle pseudo-hypertrophy may exist but are rarely observed in the first years. Muscle weakness and wasting are noted predominantly in the the scapular fixators, the biceps brachialis, the glutei muscles as well as in the posterior compartment of legs and thighs suggesting a high selectivity, a clue that is usually confirmed on muscle imaging. A gradual drop of the forced vital capacity (FVC) may be noted i a few patients especially after they turn wheelchair bound (on average 20-30 years after onset). Primary cardiac compromise has never been reported to date allowing these patients to live long. The pace of functional deterioration remains variable but overall seems slow as established by a natural history of disease studied on a four-year duration. A number of clinical variants of LGMD2A have been described in the literature. Pseudometabolic forms include exercice intolerance and myalgias. Unusual cases have been reported at both ends of the age spectrum: benign cases can present with very mild, late-onset non-progressive muscle weakness and moderately high CK levels whereas early onset, even before age 5 years, and rapid loss of ambulation are also observed. Eosinophilic myositis presentation is rare, often misleading and most probably not specific to LGMD2A. Although an autosomal recessive mode of inheritance remains the rule, a very few cases of dominantly transmitted calpain-related LGMD have recently been reported. Similarly cases where marked intra-familial variability are not that exceptional. Likewise, when it comes to compare the phenotypes between families harbouring the very same genotype suggesting the existence of modifying and/or epigenetic factors. With a wider, easier access to NGS studies, it is likely that the spectrum of these clinical exceptions to the rule will expand over time.

WS 16.2 / #54MUSCLE PATHOLOGY OF LIMB-GIRDLE MUSCULAR DYSTROPHIES (LGMD)

Topic: 01. Muscle

Kristl G. Claeys

Neurology, University Hospitals Leuven and KU Leuven, Leuven, BE

Abstract: Limb-girdle muscular dystrophies (LGMD) are a heterogeneous group of rare, genetic and progressive muscle disorders, characterized by weakness and atrophy of predominantly pelvic and shoulder girdle muscles. The inheritance pattern in LGMD is mostly autosomal recessive (LGMD2), and less frequently autosomal dominant (LGMD1). So far, 26 subforms of LGMD2 (LGMD2A-2Z) and 8 subtypes of LGMD1 (LGMD1A-1H), caused by respectively two or one mutation(s) in mostly distinct genes, have been identified. In most LGMD patients, creatine kinase (CK) level in serum is elevated. To date, pathomechanisms in LGMD are not well understood and curative treatments do not exist. Muscle biopsy in LGMD usually shows dystrophic changes consisting of necrotic and regenerating muscle fibers. Further histopathological abnormalities are increased variability in fiber diameter, elevated number of internalized nuclei and increased amount of endomysial connective tissue. Besides the general findings of necrosis and regeneration, additional pathological features can be identified in the muscle biopsy of some LGMD subforms, such as lobulated fibers in LGMD2A, eosinophils in LGMD2A, amyloid deposits in myofibers and the perivascular area in LGMD2B and LGMD2L, rimmed vacuoles in LGMD2G, LGMD1A, LGMD1D, LGMD1F and LGMD1G, and protein aggregates in LGMD1D. Perivascular and/or endomysial inflammation can be observed in some biopsies of LGMD2A, LGMD2B, LGMD2C, LGMD2I or LGMD1A patients. In some cases, the inflammatory infiltrates can even be associated with up-regulation of the major histocompatibility class 1 antigen (MHC-I), which might lead to erroneous treatment of these genetic muscle diseases with immunosuppressive agents. Also the presence of mitochondrial abnormalities in some LGMD subforms, such as LGMD1H, can lead to a wrong diagnosis of mitochondrial disease. Immunohistochemistry and immunoblotting with antibodies directed against distinct affected proteins are very helpful in the diagnosis of some LGMD subforms. Furthermore, ultrastructural findings can also add important information to the diagnosis in a few LGMD subtypes, such as the presence of sarcolemmal defects with replacement of the membrane by layers of small vesicles in LGMD2B and LGMD2L, or a reduction in caveolae in LGMD1C. With the novel massive parallel sequencing technologies rapidly entering clinical practice, there is more and more a shift in the order of diagnostic examinations to be expected. In the traditional diagnostic work-up of patients with muscle disease, a muscle biopsy is performed followed by Sanger sequencing of single candidate genes. Because of the high diagnostic rates of neuromuscular gene panels and whole-exome sequencing (WES) and their favorable cost-effectiveness, these novel massive parallel sequencing technologies are increasingly being used even before a muscle biopsy is performed. However, muscle histopathology will remain very important to study pathogenicity of the large number of variants that frequently evolve from these large genetic analyses.

WS 16.3 / #117THE ADVENT OF NGS IN LGMD DIAGNOSIS

Topic: 01. Muscle

Vincenzo Nigro¹, Marco Savarese², Annalaura Torella¹

¹Precision Medicine, Università degli Studi della Campania ”Luigi Vanvitelli”, Naples, IT;²Medical Genetics, Medicum, Folkhalsan Institute of Genetics, Uni Helsinki, Helsinki, FI

Background: Next generation sequencing (NGS) has revolutionized our approach to genetic disorders, from a single gene testing, to genomic studies. This is especially true for heterogeneous conditions with overlapping phenotypes, like limb girdle muscular dystrophies. Methods: Three different NGS strategies for DNA sequencing have been developed: a targeted re-sequencing of specific regions/genes of interest captured by specific probes or amplified by PCR; a whole exome sequencing (WES) targeting the whole set of coding regions (about 1.5% of the human genome); and a whole genome sequencing (WGS) which has no preselection of DNA fragments. Different targeted approaches have been described so far. In particular, we originally developed a strategy based on Haloplex selection MotorPlex) and capture of 89->270 genes characterized by a megabase size of the targeted regions. Using that approach about 50% of >500 undiagnosed LGMD were solved. However, the further reduction of sequencing costs provides us the opportunity to move towards WES: a unique test able to investigate, at the same time, both disease-genes and novel candidate ones. Results: Patients with undiagnosed LGMD undergo a standardized annotation using Phenotips and selected cases are recruited for trio/quartet whole exome analysis. We adopted a complete whole exome enrichment with a target of ~69Mb and a coverage of ~200x. Results are shared mainly using Phenome Central to recognize similar patients with the same genetic disease. We also optimized the bioinformatic pipeline thank to a collaboration with the Telethon Undiagnosed Program. In addition, we developed a next approach for the still negative cases. We designed a ”ultra exome” probe collection to be used in connection with the 10x Genomics. This produces a partitioning of high molecular weight DNA fragments (HMW-gDNA) into micelles, along with an adapter molecule and a barcode sequence. With this strategy, WES are fully covered and phased and even small structural variations may be detected. Conclusion: Unbiased NGS methods (like WES or WGS) may represent the first step of a comprehensive diagnostic workflow for LGMD, including traditional investigations, such as muscle biopsies and electromyography, and more specialized procedures like ultrasound muscle imaging and magnetic resonance imaging.

WS 16.4 / #35PERSPECTIVES IN CLINICAL TRIALS OF RECESSIVE AND DOMINANT LGMD

Topic: 01. Muscle

Corrado Angelini

IRCCS S.Camillo Hospital, Venice, IT

Background: The term Limb Girdle Muscular Dystrophy(LGMD) defines a progressive weakness with onset in the proximal limb girdle muscles, with age at onset of symptoms varying from early childhood(not congenital)to late adulthood. The progression of muscle weakness is usually symmetrical and variable among individuals and genetic type. These disorders present a wide spectrum of muscle involvement and wasting, spanning from very severe forms with childhood onset and rapid progression, to relatively benign forms with late onset. Methods: A consortium meeting, under the auspices of the European Neuromuscular Center, introduced a classification of LGMD based on molecular/genetic criteria. The autosomal dominant loci were designated as LGMD1, and the autosomal recessive loci were designated as LGMD2. LGMD nomenclature adopted a progressive alphabetical letter indicating the order of gene mapping identification. A new classification was proposed in an ENMC meeting held in 2017 naming autosomal dominant LGMD D and recessive forms R and numbering them. This new classification has included dystrophies with proximal or disto-proximal features, high CK presentation with histopathological evidence at biopsy of fiber degeneration/regeneration, fiber splitting, MRI imaging consistent with degenerative changes, fibro-fatty infiltration. In differential diagnosis appear the inflammatory myopathies, myofibrillar myopathies and metabolic myopathies, which can be excluded on the basis of clinical features muscle histopathology and laboratory exams. Results: LGMDs constitute a considerable fraction of all dystrophic patients and their prevalence ranges from about 8 to 70 cases per million inhabitants(1:123,000-1:14,500) depending on the geographical area and ethnic origin. The frequency of each form of LGMD is variable in different populations Calpainopathy is the most prevalent form in the majority of countries, its frequency ranges from about 10% of LGMD cases in the United States , to 80% in Basque country. Calpainopathy and Dysferlinopathy account for about 50% of total cases and primary sarcoglycanopathies are about 10-15% of cases.LGMD2I is the most common form in Northern Europe. To perform clinical trials similar pathomechanisms and homogeneous phenotypes are required. The clinical phenotypes due to mutation in the LGMD genes include instead severe childhood-onset forms, distal and proximal myopathies, pseudo-metabolic myopathies, eosinophilic myositis, and hyperCKemia. It is crucial to identify suitable selection criteria to be used in trials when treating patients after identifying defective for genes responsible for LGMD. Nowadays therapy is still an unresolved problem in LGMD mostly limited to rehabilitation, clinical follow-up of cardiological and respiratory complications.Several drugs have been tested such as corticosteroids and myostatin inhibitors with variable success. There is active pursue of new drugs and of genetic and cell therapy and a number of clinical trials are undergoing development. Conclusion: LGMDs are relatively rare and clinical trials should be done in homogeneous groups of patients after careful study of outcomes. About 8% of patients with a diagnosis of LGMD may actually have FSHD, and misdiagnosis can occur. Muscle imaging (CT-scan and MRI)may be helpful to characterize the severity at the pattern and distribution of muscle wasting and in follow up of LGMDs. Outcome measures for each clinical subtype should be carefully studied and tailored for each clinical trial.

WS 17.1 / #76PRIMARY AND SECONDARY VASCULITIC NEUROPATHY

Topic: 09. Systemic Diseases

Gerard Said

Institut Vernes, PARIS, FR

Abstract: Ischemic nerve lesions occur in primary or secondary vasculitis. The consequences of vascular inflammation and occlusion depend on the size and number of blood vessels affected. Clinical neuropathy occurs in more than 75 per cent of the patients with systemic vasculitis of the PAN group. Typically the clinical picture is that of an acute or subacute mononeuritis multiplex, with successive or simultaneous involvement of multiple nerve trunk territories over days, weeks or months. Distal symmetrical sensory or sensorimotor neuropathy also occurs. The peroneal nerve is the most commonly affected nerve. The onset of the neuropathy is typically abrupt and the deficit severe, but in many cases only partial deficit in a nerve territory is observed. Recovery from motor deficit due to ischemic neuropathy takes months, because of the axonal pattern of nerve lesions. Residual pains may be difficult to differentiate from relapses of the neuropathy. In polyarteritis nodosa (PAN) the ischemic neuropathy induced by NA can be observed as an isolated manifestation, or in the context of a multisystemic disorder. In classic PAN cutaneous vasculitis is the most common non neurological manifestation. Arthritis, renal involvement and asthma are present in 10% of patients on average. Biological markers of inflammation including CRP and ESR, increased platelet and white blood cell count with eosinophilia are often markedly elevated, but remain normal in nearly 30% of the patients seen in neurology. Churg and Strauss syndrome : In the CSS, disseminated necrotizing vasculitis occurs among asthmatic patients, with fever, eosinophilia, and a fulminant multisystem disease with pathology of NA, eosinophilic infiltration and extravascular granulomas. The vascular and nerve lesions observed in nerve biopsies from patients with this syndrome and response to treatment are actually similar to those observed in PAN, with sometimes presence of elevated ANCA. The occurrence of NA in the context of rheumatoid arthritis is associated with a poor outcome Granulomatous vasculitis (GV) is characterised by vasculitis of upper and lower respiratory tract with or without glomerulonephritis. Peripheral neuropathy has been observed in 25% of the patients with GV but peripheral neuropathy seldom is the first manifestation of the disease. Of major interest to neurologists is the occurrence of peripheral neuropathy as the only clinical manifestation of vasculitis. General signs or symptoms, usually minor, including fever and loss of weight are present in half of them. One fourth of the patients presented with a distal symmetrical ­neuropathy. The diagnosis of NA had seldom been considered before the results of the nerve and muscle biopsies. One third of patients with the so-called non systemic vasculitis subsequently developed systemic manifestations within an average 6 years, but the overall outcome remains better than in classic PAN. Vasculitic neuropathy is a frequent factor of disability in the elderly. The diagnosis of NA needs histological confirmation: the specific lesion can be found in the muscle, in the nerve, or both in the nerve and the muscle specimens, which must be studied on serial sections because NA is segmental. Nerve ischemia due to vasculitis neuropathy induces acute axonal degeneration. Secondary vasculitis: Symptomatic viral infection, by HIV infection, CMV; B and C virus hepatitis, and HTLV-1, can be associated with neuropathy and necrotizing vasculitis. Angiitis has been recognized at autopsy in the CNS and occasionally in patients with sarcoid neuropathy. A small proportion of diabetic patients over the age of 50, may present proximal neuropathy of the lower limbs characterised by a variable degree of pain and sensory loss associated with uni- or bilateral proximal muscle weakness and atrophy. Treatment: Prednisone is usually started at 1mg/Kg/day. Simultaneous treatment with cyclophosphamide, 2 mg/Kg/day, or Imuran may help reducing the doses of corticosteroids. Full dose of steroids is prescribed for 6-8 weeks and then tapered. Markers of disease activity must be checked periodically to monitor the treatment. Half of the patients relapse during tapering of prednisone or after treatment has been stopped. In some patients treatment with low dose prednisone must be pursued indefinitely. Spontaneous remissions of several years duration occur.

WS 17.2 / #102STATIN NEUROPATHIES

Topic: 09. Systemic Diseases

Hadi Manji

Mrc Centre For Neuromuscular Diseases, National Hospital for Neurology, London, GB

Background: In the United States, 37 milllion people are on statins; in the UK 13% of the population are on statins. Despite this huge number of patients taking this class of drug, reports of a peripheral neuropathy due to statins are relatively sparse when compared to the well-known myopathic side effects. It was the publication by Gaist et al, in Neurology in 2002, that the first red flag was raised regarding the risk of neuropathy with statins. This community based case control study found that stain users were 4 – 14 times more likely to develop a polyneuropathy.¹ The study was subsequently critisised on the grounds of patient selection and the criteria used for a diagnosis of neuropathy. In 2017, Gaist and colleagues published their results from a similar but larger cohort study and concluded ”statin use was not associated with an increased risk of idiopathic neuropathy.²” Nevertheless, anecdotal reports of statin related neuropathic syndromes continue to be published in the literature which are difficult to ignore. For example, Rajabally et al reported a well studied case of ”a disorder resembling Guillain-Barre syndrome on initiation of statin therapy.”³ On the contrary, the Fremantle Diabetes Study into lipid lowering therapy and peripheral sensory neuropathy in type 2 diabetes suggested that statins may in fact protect patients against the development of diabetic neuropathy.⁴ Similarly, in HIV infected patients on anti-retroviral drugs, again statins were associated with a protective effect against the development of a neuropathy.⁵ More recent evidence suggests that statins may have a role to play in the treatment of neuropathic pain. Zhang et al generated experimental models in mice and rats that mimicked trauma associated neuropathic pain. Their results indicated that simvastatin and rosuvastatin could prevent or reverse mechanical and thermal hypersensitivity in a dose dependant manner.⁶ The underlying mechanism of action is hypothesized to be related to the reduction of the expression of proinflammatory cytokines and reducing the activation of spinal microglia and astrocytes. Conclusion: The risk of statin induced neuropathy is low although it is not always possible to exclude individual idiosyncratic reactions. Statins may have a role in the prevention of neuropathy in some situations such as diabetes and HIV infection. Statins may help in the treatment of neuropathic pain as a results of their anti-inflammatory properties. References: 1) Gaist D et al. Neurology 2002;58:1333-1337 Statins and risk of polyneuropathy. 2) De Koning Svendsen et al. British Journal of Clinical Pharmacology 2017(83) 2087-2095 Statins and polyneuropathy revisited: case-control study in Denmark, 1999-2013. 3) Rajabally Y et al. Muscle and Nerve 2004:30:663-666. Disorder resembling Guillain Barre Syndrome on initiation of statin therapy. 4) Davies TME et al Diabetologia 2008:51:562-566 Lipid lowering therapy and peripheral neuropathy in type 2 diabetes: the Fremantle study 5) Chen H et al. Peripheral neuropathy in ART –experienced patients: Prevalence and risk factors. J Neurovirol 2013:19(6):557-564. 6) Xiang Qun Shi et al. Pain 2011 (152): 1033-1043. Statins alleviate experimental nerve injury-induced neuropathic pain.

WS 17.3 / #154MGUS ASSOCIATED PERIPHERAL NEUROPATHY: DIAGNOSIS AND TREATMENT

Topic: 09. Systemic Diseases

Andreas Steck

Department Neurology, Basel, CH

Abstract: A monoclonal gammopathy of undetermined significance (MGUS) is a frequent diagnosis in an elderly patient with a peripheral neuropathy (PN). It is important for the clinician to be able to determine whether an association exists between the paraprotein and the PN. The clinical phenotypes of the neuropathy, as well as the type of monoclonal protein are important clues for the diagnosis and optimal management. The prevalence of PN in patients with MGUS is about 5% in IgG, 15% in IgA and up to 30–50% in IgM MGUS. We first discuss the broad concepts of diagnostic evaluation, before presenting specifics relating to each diagnosis. The evaluation for a monoclonal protein in a patient with a peripheral neuropathy should include a serum protein ­electrophoresis and serum immunofixation electrophoresis and quantitative immunoglobulins, and serum free light chains should be obtained. The nature of the symptoms, clinical course, and involvement of motor, sensory or autonomic systems helps in the differential diagnosis. Electrophysiology delineates specific features of the different paraprotein- associated PN. Anti-MAG and anti-ganglioside antibodies (GQ1b, GM1, GD1a, GD1b) are useful tests. We will discuss and present clinical vignettes of the major clinical syndromes such as the NP associated with anti-myelin-associated glycoprotein IgM antibodies and the chronic sensory ataxic neuropathy with monoclonal IgM anti-disialosyl antibodies. NP associated with IgG and IgA MGUS often present with a CIDP phenotype. Treatment strategy for these disorders will be presented. Finally important differential diagnoses will be mentioned. This clinically oriented presentation should help neurologists improve their knowledge and stay abreast of recent advances in the field of MGUS PN.

WS 18.1 / #69AUTOANTIBODIES IN MYASTHENIA GRAVIS

Topic: 04. Neuromuscular Junction

Nils Erik Gilhus

Department Of Clinical Medicine, University of Bergen, Bergen, NO

Abstract: Myasthenia gravis (MG) is an autoimmune disease characterized by autoantibodies. The autoantibodies are directed against acetylcholine receptors (AChR) in the postsynaptic muscle membrane, or alternatively against molecules nearby that interact with AChR. The antibodies bind in vivo leading to dysfunction and reduction in AChR and defective postsynaptic signaling in muscle. MG patients should always be classified into subgroups. This classification depends on autoantibody detection, as well as age, clinical manifestations and thymus pathology.

Antibodies against muscle-specific kinase appear in 1-10% of patients, and against LRP4 in 1-3%. MG in childhood is nearly always of the early onset or ocular type. Detection of AChR, MuSK or LRP4 antibodies has a near 100% specificity for MG. The sensitivity is around 80%, highest for thymoma and lowest for ocular MG. More sensitive techniques have been developed for antibody detection, reducing the seronegative MG subgroup with one half. However, it is not known if the most sensitive assays have the same high MG specificity, and these assays are not commercially available. There is no correlation between antibody concentration and MG severity. This reflects that pathogenicity varies between antibody isotypes and idiotypes. There is a tendency for some correlation between changes in antibody concentration and clinical development in the same patient over time, so that repeated antibody measurements can be of value. Some MG patients have additional antibodies against intracellular muscle antigens, titin and ryanodine receptor in particular. Presence of such antibodies indicates thymoma or late onset MG. Patients with the antibodies tend to have more severe disease and a greater need for long-term immunosuppressive treatment. Antibodies against agrin, cortactin, and collagen Q in muscle have been detected in some MG patients without other antibodies. The MG specificity of these antibodies is not known in detail. The disease-inducing antibodies against AChR, MuSK and LRP4 all pass placenta and into the fetus during pregnancy. In approximately 20% of the newborn of MG mothers they lead to a transient neonatal myasthenia, usually with only mild symptoms for some days or a few weeks. Arthrogryposis and spontaneous abortions induced by mother’s AChR antibodies have been described in rare cases. MG is the prototype of an antibody-mediated autoimmune disease. It usually responds well to immunosuppressive therapy, so that the great majority of MG patients have rather mild disease or are in remission.

WS 18.2 / #135CIRCULATING MICRO-RNA AS BIOMARKERS IN MYASTHENIA GRAVIS

Topic: 04. Neuromuscular Junction

Anna R. Punga

Neuroscience, Uppsala University, Uppsala, SE

Background: MicroRNAs (miRNAs) are small noncoding RNA molecules, which bind specifically to different mRNA targets and thereby regulate several important intracellular biological processes. Circulating (extracellular) miRNAs can be measured in most biofluids, and therefore they have emerged as easily accessible markers in various body fluids, including blood serum and plasma, with disease-specific profiles for example in autoimmune conditions. In myasthenia gravis (MG), there is a great need for reliable objective biomarkers to monitor the disease course and therapeutic response. Recent studies in MG patients have focused on early onset MG with generalized disease phenotype. In acetylcholine receptor antibodypositive (AChR+) MG, levels of the miRNAs miR-150-5p and miR-21-5p were elevated. Further, miR-150-5p levels were lower in patients receiving immunosuppression and those having undergone thymectomy. In MuSK+ MG, another profile of circulating miRNAs is present, including upregulation of the let-7 family of miRNAs. Methods: The aim was to determine disease specific pattern of miRNAs in other subgroups of MG, including late onset MG (LOMG) and ocular MG. Different discovery cohorts consisted of patients with generalized LOMG and ocular MG as well as age- and gender-matched healthy controls (HCs). We also included longitudinal validation sets of LOMG patients to correlate disease over time with miRNA pattern. For the ocular MG cohort, we had longitudinal data and aimed at determining whether certain miRNA levels would predict generalization of MG weakness. Total RNA was isolated from 200 μl blood serum and cDNA synthesis was performed by reverse transcription, followed by real-time PCR amplification. MicroRNA expression was analyzed using the Serum/Plasma Focus microRNA PCR Panel (Exiqon) in the discovery cohorts and in the validation cohorts we added selected primers detected from the discovery cohort to the qPCR plates. Internal technical controls included interplate calibration with UniSp3, quality of RNA isolation with UniSp2 and UniSp4, cDNA synthesis control with UniSp6 and hemolysis control ΔCq (miR-23a - miR-451a). miRNA data were converted to the logarithmic scale and paired two-tailed T-test or the Wilcoxon matched paired test was used to compare the values of miRNA over time. Spearman Rank correlation was performed to find correlation between continuous factors (age, disease duration, disease severity) and different miRNAs. Statistical significance was defined as p < 0.05. Results: A pattern of miRNAs was found to be strongly elevated in the LOMG cohort and in the ocular MG cohort another pattern of elevated miRNAs was found. A few miRNAs correlated with the clinical MG composite score (MGC) and were reduced in parallel with initiation of immunosuppression and clinical improvement at 1-year follow-up. Further, levels of some miRNAs differentiated generalized from ocular MG. Conclusion: In conclusion, we found a specific pattern of miRNA expression in the subgroup of MG patients with LOMG and in the cohort of ocular MG. The correlation between some of these miRNAs with the MGC score and the clinical course strengthen the potential role of these miRNAs as biomarkers in follow-up of MG.

WS 18.3 / #105THYMUS BIOMARKERS AND CLINICAL RELEVANCE

Topic: 04. Neuromuscular Junction

Alexander Marx

Pathology, University Medical Centre Mannheim/University of Heidelberg, Mannheim, DE

Abstract not received.

WS 19.1 / #147MUSCLE BIOPSIES

Topic: 01. Muscle

Rolf Schröder¹, Monika Hofer²

¹Neuropathology, University Hospital Erlangen, Erlangen, DE;²Oxford University Hospitals, Oxford, GB

Background: Although next generation sequences approaches have certainly revolutionised the diagnostics of human muscle and nerve diseases, there is still an essential role for muscle biopsies in the diagnostic work-up of patients with neuromuscular symptoms. However, appropriate indications, careful choice of muscle to biopsy and appropriate handling and work-up of the muscle tissue are of paramount importance to ensure a high diagnostic yield. Methods: Light and electron microscopic analysis of skeletal muscle tissue in conjunction with immunohistochemistry of essential disease-related muscle proteins. Results: Our talk will address the following issues: 1. Indications and contraindications 2. Choosing the right muscle for biopsy 3. Essentials for handling and further work-up of muscle tissue 4. Standard histochemical staining panel and basic interpretation of results 5. Standard immunohistochemical staining panel and basic interpretation of results 6. Indications for electron microscopy analysis and basic interpretation Conclusion: Diagnostic muscle biopsies are still an invaluable tool in the diagnostic work-up of neuromuscular patients. This presentation discusses the aspects mentioned above and is primarily aimed at neurologists looking after muscle patients. Selected cases will be used to demonstrate the principles.

WS 19.2 / #65NERVE BIOPSIES:  THERE IS STILL A PLACE FOR NERVE BIOPSY IN MODERN CLINICAL PRACTICE

Topic: 01. Muscle

P. James B. Dyck

Mayo Clinic, Rochester, US

Background: Nerve biopsy is a useful tool for the diagnosis and treatment of peripheral neuropathies but the need for its continued use in the future has been questioned. With improvement in laboratory, radiographic and electrophysiological evaluations, nerve biopsy use has been on the decline. With better understanding of the pathophysiology, some neuropathies no longer need to be biopsied (inherited) whereas others can be recognized by the disease pattern (CIDP). Methods: Herein, we review our approach to doing nerve biopsies including selection of appropriate patients and nerve biopsy sites. Results: When deciding to do a nerve biopsy, there are some features that are helpful. A thorough neurological evaluation should be completed before nerve biopsy is performed. Patients with rapidly worsening, progressive neuropathies who have major clinical deficits are good biopsy candidates. Traditionally, whole distal cutaneous nerve biopsies are performed. These are taken from sensory nerves (e.g. sural, superficial peroneal, saphenous, superficial radial, etc.) and so are only useful in sensorimotor or pure sensory neuropathies. The nerve needs to be clinically affected in order for a nerve biopsy to show findings. Nerve biopsies laboratories should do a wide variety of preparations including teased fibers, paraffin and epoxy sections, immunohistochemistry and electron microscopy. Reports on the diagnostic yield of nerve biopsy vary and the findings are hard to validate because the quality of the evaluations and of the pathological specimens vary. In our experience, nerve biopsies from carefully selected patients frequently show important findings that change clinical management. For motor predominant, focal or proximal neuropathies the traditional distal cutaneous biopsy may be inadequate. With improved resolution of MRI, focal lesions along the nerve can now be identified and biopsied. We have extensive experience with targeted fascicular nerve biopsies and find that about 84% of these targeted biopsies reveal meaningful pathology from which 76% are potentially treatable. Such cases usually are focal or multifocal, proximal or motor predominant. The causes include inflammatory demyelinating, vasculitis, sarcoidosis, amyloidosis, leprosy, lymphoma, metastatic tumors, vascular malformations and others. Conclusion: There is strong evidence that nerve biopsy should still be performed in selected patients in modern neurological practice. For most typical length-dependent neuropathies whole distal cutaneous biopsy is the procedure of choice. In contrast, for focal motor predominant or proximal neuropathies targeted fascicular nerve biopsy is a superior approach. Patients should be carefully screened and have a thorough evaluation and only patients with severe neuropathies that have a high likelihood of being treatable should be biopsied to offset potential side effects. Biopsies should be performed at centers with expertise in peripheral nerve diseases with specialized neurologists, radiologists, peripheral nerve surgeons and pathologists and laboratories that offer a variety of nerve preparations to ensure maximal benefit with minimal morbidity.

WS 19.3 / #91SKIN BIOPSIES

Topic: 01. Muscle

Giuseppe Lauria

”Carlo Besta” Neurological Institute, Milan, IT

Abstract not received.

WS 20.1 / #99DIABETIC CRANIAL NEUROPATHIES

Topic: 09. Systemic Diseases

Tudor Lupescu

Department Of Neurology, ”Agrippa Ionescu” Hospital,, Bucharest, RO

Background: Diabetes mellitus is a frequent condition representing nowadays practically a pandemic with a prevalence of almost 1 in every 10 people. There is also a high prevalence of neuropathy among diabetic patients, of about 50%. The cranial nerves affected in diabetes are the oculomotor (3rd, 4th, and 6th) and the facial. Although cranial neuropathies represent 1-2% of the total diabetic neuropathies, due to the very high number of diabetic patients, most neurologists will encounter such cases. Methods: The presentation will deal with the two most frequent types of cranial neuropathies, namely those that involve the oculomotor and the facial nerves. Results: All the oculomotor nerves can be involved, but neuropathy of the 3rd cranial nerve is the most frequent. It is followed by involvement of the abducens and the trochlear nerve. The common oculomotor diabetic neuropathy is characterized by sudden onset of palpebral ptosis, diplopia, divergent strabismus, usually preceded by ocular pain. Sparing of the pupillary function is quite typical for diabetic palsy of the third cranial nerve. This feature is explained by the ischemic mechanism of this neuropathy, with involvement of the centrofascicular portion of the nerve, leaving intact the fibres concerned with pupillary function that are situated more peripherally. Abducens nerve palsy can be recognized by the convergent strabismus. Trochlear nerve palsies are rare. The differential diagnosis of these cranial neuropathies is very important, since other conditions in which the oculomotor nerves are affected can be very significant and dangerous. We must exclude an aneurysm of the posterior communicating artery, midbrain ischemia, or tumour. Therefore a thorough clinical examination and neuroimaging are very important in the management of these cases. The prognosis for recovery is good. The diabetic facial palsy is more frequent in older diabetics than in non-diabetic patients. The clinical presentation is similar to the common Bell’s palsy. There is an acute onset of unilateral weakness of facial muscles, often preceded by retroauricular pain. A study showed that in the majority of diabetic patients, there was no taste abnormality. Therefore it was assumed that the lesion in diabetic facial palsies is most often distal to the chorda tympani. Of course it is important to see that other signs of central nervous involvement are absent, otherwise we might misdiagnose important clinical conditions (stroke, multiple sclerosis). The clinical examination and neuroimaging are useful here. Sometimes, electrodiagnosis (nerve conduction studies, blink reflex) can add important functional data. As in idiopathic facial palsy, the prognosis for recovery is good. There are situations in which cranial nerve palsies accompany more serious conditions, associated or not with diabetes. There are cases with oculomotor nerve involvement in mucormycosis, and also cases with facial and cervical radiculoplexus neuropathy. Conclusion: Although rare among associated neuropathies, the high prevalence of diabetes mellitus provides a significant number of cases with cranial nerve neuropathies. Thus, knowledge regarding these conditions is important, since they present with an acute onset, pain, and may mimic other important and sometimes life-threatening diseases.

WS 20.2 / #75MUSCULOSKELETAL COMPLICATIONS OF DIABETES ARE COMMON AND UNDERDIAGNOSED

Topic: 09. Systemic Diseases

Anna Grisold

Medical University of Vienna, Vienna, AT

Background: Diabetes mellitus (DM) is a disease with an enormous socio-economic impact and a still increasing prevalence worldwide. The underlying pathophysiology of type I DM is an autoimmune destruction of pancreatic cells, whereas in type II DM insulin resistance, hyperglycemia and inadequate insulin secretion are the main mechanisms. Persistent hyperglycemia subsequently leads to microvascular complications such as nephropathy, neuropathy and retinopathy and macrovascular complications like stroke, coronary and peripheral artery diseases. Further, musculoskeletal disorders represent a broad spectrum of still underestimated comorbidities in diabetes. The exact pathomechanisms of musculoskeletal complications still remain elusive. Muscle inflammation, fibrosis, infarction, hemorrhage, necrosis, neuropathy and vasculopathy have been discussed as concomitant structural alterations. From an etiological point of view, disease duration as well as disease control, age and comorbidities play a crucial role in the development of musculoskeletal complications. Musculoskeletal complications in DM: Regarding complications of the skeleton, upper extremities are more often affected than lower extremities. Common manifestations include ”frozen shoulder” syndrome due to adhesive capsulitis, but also limited joint mobility, Dupuytren’s contractures, flexor tenosynovitis, carpal tunnel syndrome and diffuse idiopathic skeletal hyperostosis. In the lower extremities, especially in the feet, skeletal complications are usually more disabling, for example Charcot’s joint of the ankle and foot. Apart from the aforementioned skeletal involvement, also muscle tissue might be affected by DM. Sarcopenia and muscle atrophy as generalized presentations, but also painful muscle infarcts are characteristic. Additionally, infectious and inflammatory myositis may be observed. Given their generally impaired metabolic state, diabetic patients are particularly prone to infectious complications in articular structures. Also a decreased bone density has been described in the literature. Therapy: Glycemic control due to pharmacotherapy and diet are the most important therapeutic options. Besides, the anti-inflammatory and immune-mediating effect of corticosteroids may be used in the treatment of musculoskeletal disorders in DM patients. However, the indication has to be chosen carefully in consideration of potentially resulting metabolic perturbations. A regular and sensible physiotherapy program is an important cornerstone of DM management to prevent further musculoskeletal complications and strengthen the patient. Conclusion: Musculoskeletal complications are frequent, but still underestimated in patients with DM. They often present with reduced mobility and pain, which might be difficult to distinguish from peripheral nerve lesions. This lecture points out the most important and frequent musculoskeletal complications in patients with DM.

WS 20.3 / #128ATYPICAL NEUROPATHIES IN DIABETES: DIAGNOSIS AND MANAGEMENT

Topic: 09. Systemic Diseases

Amanda Peltier

Vanderbilt University, Nashville, US

Abstract not received.

WS 20.4 / #50TREATMENT INDUCED AND INFLAMMATORY NEUROPATHIES IN DIABETES

Topic: 09. Systemic Diseases

Brian Christopher Callaghan

University of Michigan School of Public Health, Ann Arbor, US

Abstract: Patients with diabetes may experience multiple types of periperhal neuropathies. The most common is distal symmetric polyneuropathy; however, other less common neuropathies such as treatment induced neuropathy (TIND), chronic inflammatory demyleinating polyneuropathy (CIDP), and diabetic lumbosacral radiculoplexus neuropathy (LSRPN) may also occur. In patients with diabetes, TIND is often unrecongnized. The neuropathy predominantly affects small nerve fibers leading to a length dependent, painful neuropathy as well as an autonomic neuropathy. This neuropathy usually occurs when the HA1C falls 3 or more points in 3 months. Patients with type 1 and type 2 diabetes can both have this complication. Recurrent events can lead to large fiber injury and worse patient outcomes. The more autonomic involvement that occurs, the less likely the disease is to be recognized. Only 5% of mild TIND and 41% of severe neuropathy is recognized by treating physicians. TIND should be considered in patients with diabetes that have abrupt changes in pain and/or autonomic symptoms. Typical diabetic polyneuropathy presents slowly; therefore acute/subacute presentations are a red flag for an atypical neuropathy such as TIND. Inflammatory neuropathies, such as CIDP may also be more common in patients with diabetes. Multiple groups have shown that the prevalence of CIDP is higher in patients with diabetes than in those without diabetes. Furthermore, another study demonstrated that the treatment responsiveness is not different between patients with CIDP with and without diabetes. However, patients with CIDP and diabetes require more EFNS criteria to have the same treatment responsiveness as those without diabetes. Fulfilling more EFNS criteria increases the likelihood of treatment response in those with diabetes. A separate study found that patient with CIDP and diabetes are less likely to be treatment than those without diabetes. Despite these studies, other investigators have found that the prevalence of CIDP is not higher in those with diabetes than those without. This group has also reported patients with painless motor neuropathy in diabetes that they believe is a LSRPN and not CIDP. LSRPN also occurs more commonly in patients with diabetes compared to those without. This peripheral neuropathy usually presents with severe pain, followed by weakness, followed by some degree of recovery. Patients typically have an asymmetric presentation with proximal weakness in one leg more than the other. The only clinical trial did not show benefit of weekly IV steroids on the primary outcomes, but did lead to reduced pain. A cervical variant of this condition also occurs, but is less common. Methods: Review of the literature Results: summarized in the background. Conclusion: Diabetes is associated with many manifestations of peripheral nerve injury. In addition, to distal symmetric polyneuropathy, TIND, CIDP, and LSRPN can also occur.

TC 1.1 / #58CLINICAL PHENOTYPES AND HOW TO MANAGE PATIENTS WITH HIGH HYPERCKEMIA, STATIN MYOPATHY

Topic: 01. Muscle

Marianne De Visser

Department Of Neurology, Academic Medical Centre, Amsterdam, NL

Abstract not received.

TC 1.2 / #145HOW TO DIAGNOSE A PATIENT WITH HYPERCKEMIA

Topic: 01. Muscle

Sabrina Sacconi

Centre de référence des Maladies Neuromusculaires, Hôpital Archet, France. CNRS UMR7277, INSERM U1091, IBV - Institute of Biology Valrose, UNS Université Nice Sophia- Antipolis, Faculté de Médecine, Nice, FR

Abstract: Rhabdomyolysis ranges to an asymptomatic illness to a life-threatening condition associated with electrolyte imbalances, acute renal failure and disseminated intravascular coagulation. It results from skeletal muscle injury followed by the release of muscle contents into the plasma. The most sensitive laboratory finding of muscle injury is an elevated plasma creatine kinase level. Creatine kinases (CK) is a dimeric enzyme catalyzing the reversible phosphorylation of creatine by adenosine triphosphate. The CK enzyme is composed of subunits derived from either muscle (M) or brain (B). Three isoenzymes have been identified, and they are present in several tissues: striated muscle (MM), heart tissue (MB), and brain (BB). As a consequence of cardiac or brain injury MB and BB isoforms may be elevated. Increase in CK can be also seen in several physiological conditions: CK levels transiently rise after exercise or heavy manual labor; they vary significantly by sex and race, possibly in relation to differences in muscle mass or total body mass, and/or inherited differences in the permeability of the sarcolemma to CK. There is also a small reduction in CK levels as people age. In pathological conditions, weakness, myalgia and tea-colored urine can be associated to increase in CK. Muscular trauma is one of the most common non-neuromuscular causes of rhabdomyolysis. Less common causes include electrolyte abnormalities, vessels occlusion, shock state, infectious causes, drugs, toxins, endocrinopathies, auto-immune diseases. A large spectrum of neuromuscular conditions can be diagnosed in presence of acute recurrent or chronic rhabdomyolysis including inflammatory and necrotizing myopathies, metabolic diseases as glycogenosis, B oxidation disorders, mitochondrial myopathy, lipidosis, pseudo metabolic presentation of muscular dystrophy or congenital myopathies. The diagnostic work-up may be complicated by the fact that, among the patients displaying increased CK, asymptomatic or pauci symptomatic carriers as well as early stages myopathies may be diagnosed. High CK can also be found in patients suffering from peripheral nervous system or motor neuron disease associated to extensive muscle wasting. The objective of this teaching course is to describe the aetiological spectrum of acute recurrent and chronic rhabdomyolysis and to provide an appraisal of the current strategies available to facilitate early diagnosis of this condition. Early diagnosis will allow early therapy when available, and prevention and/or the prompt management of acute and chronic complications. On this purpose, muscle biopsy is still the key exam in order to solve the large majority of myopathic-related causes of rhabdomyolisis, but it appears the more and more evident that new technologies are changing the way to address this issue and may, in the next future, reduce the need of this invasive approach. We will discuss the role of these new and powerful technologies, especially when unraveling genetic associated diseases, combined with more traditional approaches including an accurate clinical examination, standard biological exams, electrophysiology and muscle MRI, that are, despite all that, still necessary to guide the interpretation of the results. Since the field of new technologies is rapidly evolving, future researches are required to establish algorithms for cost-effective medical care.

TC 1.3 / #36HYPERCKEMIA IN MUSCULAR DISTROPHIES AND METABOLIC MYOPATHIES

Topic: 01. Muscle

Corrado Angelini

IRCCS S.Camillo Hospital, Venice, IT

Background: Hyperckemia is a common finding in asymptomatic and paucisymptomatic muscle patients, that can precede the onset of several myopathies. The first description was by Rowland in MDR Symposium held in Venice in 1980 and this generated an interest by clinicians and patients with either high CK or paucisymptomatic clinical presentation such as cramps or exercise intolerance. Methods: A literature review was performed using the following keywords: metabolic myopathies, Pompe disease, Mc Ardle disease, disorder of lipid metabolism, high CK, biopsy, MRI. Since then this entity has been covered by international guidelines in order to handle such patients and perform exams and in such guidelines need to include nowdays muscle CT/MRI imaging. Results: The most common muscular dystrophies that appear first as isolated hyperckemia are calpainopathy, disferlinopathy or alpha-sarcoglycanopathies. High CK in females evokes as first suspicion the carrier status for dystrophinopathy. An increase of CK in pauci/asymptomatic male can be due to juvenile onset Pompe disease, that is the first hereditary myopathy for which a registered treatment is available, it is therefore important to diagnose such cases. A similar screening was done in the LOPED study by DBS assay, that identified numerous late onset Pompe phenotypes presenting with hyperckemia or mild LGMD phenotype that subsequently were found to have pathogenetic mutations in GAA gene and underwent ERT treatment. Mc Ardle patients suffer from cramps and exercise intolerance. The timing of onset of symptoms in relation to exercise provides a clue to the nature of the underlying problem and guides further investigation. Glycolysis is the main source of energy at rest and during sustained moderate exercise. In early exercise, particularly during high-intensity exercise such as weight lifting or sprinting, and before adaptive changes, such as increased respiration and blood flow, muscle energy demands are met primarily by anaerobic glycolysis. In muscle glycogenolytic ­disorders myalgia develops early during exercise, in most cases the onset of symptoms starts in childhood. In these conditions, fixed weakness may develop later in life. Recurrent myoglobinuria is common in all these disorders, a history of a ‘second wind’ phenomenon is suggestive of McArdle disease. This disorder is caused by a lack of glycogen breakdown due to mutations in the muscle glycogen phosphorylase(myophosphorylase). The nonsense p.R50X stop codon mutation accounts for 43% of cases of myophosphorylase deficiency in caucasian populations and ACE I/D polymorphism influences severity of disease expression. Fatty acids are the major substrate at rest and in prolonged low-intensity exercise, such as during a marathon. In lipid storage disorders elevated CK can be observed in carnitine deficiency, in ETF dehydrogenase deficiency. Myalgia or myoglobinuria in fatty acid oxidation defects occur later in exercise than in glycogenolytic disorders. Conclusion: Serum CK varies greatly depending on prior physical activity level and is typically elevated in patients with complete enzymatic blocks (myophosphorylase and phosphofructokinase deficiency)or in muscular dystrophies. In fatty acid disorders recurrent myoglobinuria following prolonged aerobic exercise is common in a number of lipid disorders, especially if preceded by fasting. Between attacks CK is usually normal at difference with muscular dystrophy.

TC 1.4 / #87DIAGNOSTIC APPROACH AND GUIDELINES FOR OLIGOSYMPTOMATIC HYPERCKEMIA

Topic: 01. Muscle

Theodore Kyriakides

Clinic A, Cyprus Institute of Neurology and Genetics, Nicosia, CY

Background: Increased serum creatine kinase (CK) above the upper limit of normal (ULN) or hyperCKemia is a frequent finding among the normal population and prevalence rates of persistent hyperCKemia of 1.3% have been reported. The overwhelming majority of these individuals are oligo/asymptomatic and hyperCKemia is a chance finding. The dilemma often arises as to whether there is an underlying ­myopathy which could potentially evolve into clinically significant weakness in the future or whether such an individual could be at risk by certain drugs such as statins. Current evidence suggests that on a population basis the likelihood of discovering a significant cause for oligo/asymptomatic and hyperCKemia is extremely low and routine investigation of such individuals is not cost-effective. Potential tools for investigation include the muscle biopsy, specific DNA testing and muscle panel DNA testing made possible by Next Generation Sequencing. Methods: In the absence of RCTs to provide a diagnostic strategy, case-based observational studies could be interrogated in an attempt to provide posItive and negative predictive values of certain parameters so selected patients could be investigated.Such parameters could be ; age of the patient, symptoms, level of hyperCKemia and the EMG. Results: Data will be presented on the positive and negative predictive value on reaching a diagnosis in patients with hyperCKemia following biopsy according to patient’s age, level of hyperCKemia, symptoms and EMG result. Conclusion: Randomised control studies are not available to guide a diagnostic strategy in oligosymptomatic patients with hyperCKemia. An approach based on available evidence from observational studies has to be used to optimise investigations of such patients.

TC 2.1 / #132SYNAPTIC SIGNALLING PATHWAYS IN NEUROMUSCULAR JUNCTION DEVELOPMENT AND PATHOPHYSIOLOGY

Topic: 04. Neuromuscular Junction

William D. Phillips

Physiology, The University Of Sydney, Sydney, NSW, AU

Abstract: Myasthenia gravis provides the clearest example of impaired neuromuscular transmission, but compromised nerve-muscle communication can contribute to weakness in diverse diseases and conditions. Mouse models of Duchenne muscular dystrophy reveal relatively mild impairments of neuromuscular transmission. In contrast, loss of nerve terminals from motor endplates seems to begin early in the progression of motor neuron disease. A slower, progressive loss of neuromuscular connections occurs in old age. In elderly mice, at least, this loss of neuromuscular connections could be slowed by exercise or dietary restriction. Mouse studies also show that failure of two-way synaptic communication can contribute to failure of neuromuscular transmission, and/or loss of nerve-muscle connections. Most of what we know about the interactions between nerve and muscle has come from studying embryonic development of the neuromuscular junction (NMJ). Muscle specific kinase (MuSK), a transmembrane tyrosine kinase, is a central player in formation of the NMJ. A small patch of MuSK in the central region of the embryonic muscle fibre marks the site for the future NMJ. The intrinsic kinase activity of MuSK recruits acetylcholine receptors (AChR) and the cytoplasmic adaptor protein, rapsyn, so as to form specialized postsynaptic membrane. A cytoplasmic protein called DOK7 binds directly to MuSK dimers. Higher levels of DOK7 expression elevate the intrinsic kinase activity of MuSK. As ­motor axons invade embryonic muscles they secrete a proteoglycan called neural agrin. Neural agrin binds a complex of LRP4 and MuSK, which further increases MuSK activity. The agrin-LRP4-MuSK-rapsyn pathway stabilizes the AChR-rich postsynaptic membrane beneath the nerve terminal. Acetylcholine acts via postsynaptic AChR and calcium-activated proteases to drive an opposing system that tends to remove AChRs from the AChR patch. During normal development, agrin-driven AChR stabilization and acetylcholine-driven AChR disassembly balance each other. This helps to align postsynaptic AChRs beneath the growing presynaptic nerve terminal. Meanwhile postsynaptic LRP4 and synaptic-cleft laminins signal back to the overlying axon membrane to induce the assembly of presynaptic acetylcholine release machinery. The same molecular mechanisms that control development of the embryonic NMJ remain vital for sustaining effective neuromuscular connections through adult life. Loss-of-function mutations that affect neural agrin, LRP4, MuSK, DOK7, or rapsyn can each give rise to congenital myasthenias. A subset of myasthenia gravis patients display IgG4-type MuSK autoantibodies that inhibit the activation of LRP4-MuSK by neural agrin. When injected into adult mice these antibodies cause disassembly of the postsynaptic AChRs, leading to myasthenic weakness. The MuSK antibodies also disrupt the adaptive increase in presynaptic acetylcholine release. In this mouse model, where MuSK function is impaired, the acetylcholine-driven AChR disassembly pathway can be perilous. Pyridostigmine (a first line treatment for anti-AChR myasthenia gravis) exacerbated the loss of postsynaptic AChRs. Studies in mouse models neuromuscular disease suggest that enhancing MuSK activity can help prevent failure of neuromuscular control. A better understanding of how the MuSK system operates in mature muscle will be needed before the therapeutic potential of MuSK can be properly understood.

TC 2.2 / #524NEUROMUSCULAR TRANSMISSION AND ITS ASSESSMENT

Topic: 04. Neuromuscular Junction

Clarke Slater

Institute Of Neuroscience, Newcastle University, Newcastle Upon Tyne, GB

Abstract: Neuromuscular transmission provides the essential link between neural commands and the coordinated muscle contractions that turn them into useful actions. In a clinical setting, the efficacy of transmission can be assessed by recording the summed electrical activity of many muscle fibers, using either large electrodes on the muscle surface or needle electrodes inserted into the muscle. In both cases one records compound muscle action potentials (CMAPs) which reflect the activity of many muscle fibers. In normal subjects, during repetitive nerve stimulation at frequencies of up to 100 Hz, the amplitude of the CMAP remains constant, but in some patients there is a significant (>10%) ‘decrement’ of the response, indicating that some of the neuromuscular junctions (NMJ) are unable to follow faithfully the pattern of stimulation. To investigate the basis of such failure in detail, it is necessary to make intracellular recordings from individual NMJs in isolated nerve-muscle preparations. When the electrodes are placed within 1 mm or so of an NMJ, one records both evoked and spontaneous depolarizations from the resting potential of about -75 mV. The evoked endplate potentials (EPPs) are typically about 40 mV in amplitude, but to record them special precautions must be taken to block action potentials and contractions. Spontaneous miniature EPPs (mEPPs) occur at a frequency of about 1 Hz. These result from the action of multimolecular ‘quanta’ of acetylcholine (ACh), the contents of individual ­presynaptic vesicles (SVs), on the muscle fiber surface. A nerve impulse causes entry of Ca²⁺ into the nerve terminal which normally triggers the release of 20-200 quanta whose effects sum to make up the EPP. Because the effects of mEPPs do not add linearly, the number of quanta released, or ‘quantal content’ (QC), is best estimated from recordings of the synaptic currents (EPCs and mEPCs). This is done using 2 intracellular electrodes, one to record voltage and the other to pass current, in a ‘voltage-clamp’ arrangement. Usually substantially more quanta are released in response to a single nerve impulse that are required to activate the muscle fiber, giving the process of transmission a high ‘safety factor’. Muscles are normally activated by bursts of 5-10 nerve impulses at up to 100 Hz or longer trains at lower frequency. In response to repetitive stimulation, the QC at individual NMJs declines, but the high safety factor of transmission means that the EPP normally remains large enough to trigger an action potential. In patients with impaired neuromuscular transmission, the EPP may fall below threshold, resulting in a failure of muscle fiber activation. Different factors may cause a reduction of EPP amplitude. These include; reduced AChR density (e.g. MG, AChR deficiency), reduced QC resulting from impaired quantal release (e.g. LEMS, various forms of CMS), and reduced QC resulting from reduced NMJ area (e.g. DOK-7 myasthenia).

TC 2.3 / #158PRESYNAPTIC RECEPTORS AND NEUROMUSCULAR TRANSMISSION

Topic: 04. Neuromuscular Junction

Ana M. Sebastião

Faculty Of Medicine, Institute Of Pharmacology And Neurosciences And Institute Of Molecular Medicine, University of Lisbon, Lisboa, PT

Background: The neuromuscular junction has unique properties to evaluate presynaptic mechanisms and receptors: 1. It has a relatively simple and well known structure. 2. There is only one nerve terminal per each skeletal muscle fibre, each synaptic response thus corresponding to the activity of a single nerve terminal. 3. There is only one type of neurotransmitter being released, acetylcholine, though several neuromodulators are also released to control synaptic function, as it is the case of ATP and adenosine. Acetylcholine itself can also act as a neuromodulator, controlling its own release and function. 4. It is possible to record from the synaptic region, in contrast with what occurs in most central nervous system synapses. 5. Changes in the amount of neurotransmitter released per nerve impulse (quantal content) can be easily quantified. Methods: Using the neuromuscular junction as a model, it could be established that: Results: 1. ATP, which is released together with acetylcholine as well as from peri-synaptic Schwann cells (PSCs), is extracellularly converted into adenosine through a cascade of enzymes, denominated ecto-nucleotidases 2. Adenosine, by acting through G-protein coupled receptors, can either inhibit or facilitate acetylcholine release, through A1 (inhibitory) or A2A (excitatory) receptors that can co-exist in the same nerve terminal. 3. At low frequencies of stimulation the influence of adenosine is inhibitory, but at higher stimulation frequencies it can become excitatory. 4. Adenosine is removed from the synaptic cleft through equilibrative adenosine transporters. 5. ATP itself acts on PSCs through Gq-coupled ATP receptors, leading to calcium signals that induce the release of more ATP from these cells. 6. Calcium signals in PSCs can also be evoked by acetylcholine through Gq-coupled muscarinic receptors. 7. Muscarinic and nicotinic acetylcholine receptors are also present in the nerve terminal to control ACh release. During disease states this fine-tune control of neurotransmission may become dysfunctional, as it is the case of Amyotrophic Lateral Sclerosis. Using disease models, it was found that at very early stages, there is an unbalanced modulation of calcium homeostasis in the nerve terminal and PSCs, which reflects in enhanced but asynchronous ACh release. Concomitantly, there are alterations in muscarinic receptor function in PSCs as well as A1 and A2A receptor function in motor nerve terminals, which are already evident in the pre-symptomatic stage. Interestingly, some of these excitatory alterations fade away at symptomatic states of the disease, where a global inhibition of neuromuscular transmission becomes evident. Conclusion: Summing up, the simplicity of the neuromuscular junction allowed to unravel further levels of synaptic complexity, which extend to non-neuronal components and allow fine-tune modulation of synaptic activity. This fine-control fails in several pathologies, as we found in Amyotrophic Lateral Sclerosis model. Initially there is an exacerbated and unbalanced excitatory activity, which collapses at a later stage of disease progression, leading to a progressive failure of neuromuscular transmission. Work supported by LISBOA-01-0145-FEDER-007391, co-funded by FEDER through POR Lisboa 2020 (Programa Operacional Regional de Lisboa) from PORTUGAL 2020 and Fundação para a Ciência e Tecnologia (FCT) and by a Twinning action (SynaNet) from the EU H2020 programme (project number: 692340).

TC 2.4 / #95DIAGNOSIS AND THERAPY FOR NEUROMUSCULAR TRANSMISSION DISORDERS - MYASTHENIA GRAVIS AND CONGENITAL MYASTHENIC SYNDROMES

Topic: 04. Neuromuscular Junction

Hanns Lochmüller

Department Of Neuropediatrics And Muscle Disorders, Freiburg University - Medical Center, Faculty of Medicine, Freiburg, DE

Background: Neuromuscular junction disorders, also called Myasthenic syndromes (MS), are a rare heterogeneous group of acquired (Myasthenia Gravis, MG) and inherited (Congenital Myasthenic Syndromes, CMS) neuromuscular disorders associated with distinctive clinical, electrophysiological, laboratory and ultrastructural abnormalities. Methods: MG has been associated with auto-antibodies against the acetylcholine receptor (AChR) or MuSK, and more recently with other antibodies in rare cases. Therapy is based on esterase inhibitors, immune therapies and thymectomy. Recent advances in understanding and clinical research have led to treatment guidelines, which were developed by a subcommittee of the American Academy of Neurology which are under consideration for adoption by the European Reference Network for Rare Neuromuscular Disorders (EURO-NMD). Results: The genetic defects in CMS either impair neuromuscular transmission directly or result in secondary impairments, which eventually compromise the safety margin of neuromuscular transmission. More recently, we have identified two genes (DOK7, GFPT1) that cause fatigable weakness of muscles in a limb-girdle distribution, but rarely affecting facial or eye muscles. Next-generation ­sequencing and deep phenotyping, in combination with international data sharing, reveals new genetic causes of CMS, but also unusual, overlapping clinical phenotypes which blur the boundaries with primary myopathies and motor neuropathies (SYT2, GMPPB). Conclusion: We will cover the significant progress made in understanding the molecular pathogenesis of CMS and MG, which is important for both patients and clinicians in terms of reaching a definite diagnosis and selecting the most appropriate treatment. Moreover, new avenues of clinical and translational research will be addressed.

TC 3.1 / #40CMT NEUROPATHIES IN THE ELDERLY

Topic: 02. Neuropathy

Michaela Auer-Grumbach

Department Of Orthopaedics, Medical University of Vienna, Vienna, AT

Abstract: Axonal neuropathies are frequently observed in the elderly and may lead to progressive disability. The underlying causes often remain elusive. However, recent studies have identified pathogenic variants in genes known to be involved in Charcot-Marie-Tooth neuropathy type 2 (CMT2) disease in patients with and without family history. We present clinical and genetic data of 126 index patients with unexplained progressive axonal neuropathies and disease onset after age 35 years. Whole exome sequencing has been carried out in all probands. In more than 20% of the patients we observed one or two variants in MME, encoding the metalloprotease neprilysin. We detected heterozygous, homozygous and compound heterozygous loss-of-function and missense mutations in our probands and therefore confirm that MME mutations may segregate in an autosomal dominant and autosomal recessive fashion. Whenever possible, neprilysin levels in plasma were determined and correlated with particular variants and associated phenotypes. In further patients we identified pathogenetic or likely pathogenic variants in other genes known to cause late onset neuropathies (MPZ, LRSAM1, TTR, GARS, HARS, AARS, HMBS, HSPB8, MFN2, DHTKD1, WARS). Still more than 50% of the probands did not receive a genetic diagnosis and remain unexplained but further evaluation of WES data is ongoing.

TC 3.2 / #180ESSENTIAL CLUES TO EARLY RECOGNITION OF AMYLOID NEUROPATHIES

Topic: 02. Neuropathy

Davide Pareyson

Dept Of Clinical Neurosciences, IRCCS Foundation, C.Besta Neurological Institute, Milan, IT

Abstract: Inherited transthyretin amyloidosis (ATTR) is an autosomal dominant disorder due to mutations of the transthyretin (TTR) gene. TTR is synthetized mainly by the liver and released in plasma as a tetrameric transport protein. Mutations in TTR, of which Val30Met is the most common worldwide, cause transthyretin tetramer dissociation, monomer misfolding, and aggregation into insoluble fibrillar proteins in different tissues. Peripheral nerves and heart are the most frequently affected organs, but also eye, leptomeninges and kidneys can be involved. As there are effective treatments which are already available or will soon be marketed, and such treatments are more effective in the first disease phases, early diagnosis is fundamental for preventing disease progression in this otherwise lethal disorder. Early diagnosis is easier in familial cases in endemic regions, where Val30Met is by far the predominant mutation, degree of awareness is high, and presentation is typical, i.e., a predominantly small-fibre length-dependent sensory neuropathy with dysautonomia, only later involving motor fibres. Diagnosis is often delayed in non-endemic region where onset occurs much later in life, family history if often negative or misleading, dysautonomia is more subtle, presentation is atypical with a sensory-motor polyneuropathy involving all fibre types (or with other atypical presentations), and progression is definitely faster. ATTR-neuropathy must be considered in the differential diagnosis of any rapidly progressive neuropathy, particularly if later in life. Red flags are: association with carpal tunnel syndrome, early dysautonomia (particularly impotence in males), gastrointestinal involvement, neuropathic pain, loss of weight, fasciculations. When dealing with a patient with a possible TTR-related neuropathy, the clinician should look for evidence of clinical or subclinical involvement of other target organs: ocular involvement with vitreal opacities, glaucoma, pupillary anomalies; cardiac ­involvement with arrhythmia, conduction blocks, interventricular septum hypertrophy, overt cardiomyopathy; proteinuria, renal failure, recurrent urinary tract infections. Ecocardiography, Technetium-99m-diphosphonate (99mTc-DPD) scintigraphy showing abnormal cardiac tracer accumulation, cardiac MRI, tilt test, sudomotor function testing are all ancillary investigation which may give clues to amyloidosis. Increased brain natriuretic peptide (BNP) levels may reveal subclinical cardiopathy, glomerular filtration rate is an important disease biomarker. Biopsies can be helpful by demonstrating tissue amyloid accumulation in nerve, abdominal fat, salivary glands, skin, and gastro-intestinal tract, but may also fail in detecting amyloid. A careful nerve conduction study with EMG is important but results may be aspecific; nerve conduction slowing is not infrequent and may be misleading. CSF protein content may be increased, explaining the high rate of misdiagnosis with CIDP. Other incorrect diagnoses include lumbar stenosis and Charcot-Marie-Tooth disease. However, if the clinical picture is compatible with ATTR-neuropathy the clinician should ask for genetic testing, which provides a definite diagnosis.

TC 3.3 / #78SENSORY AND AUTONOMIC HEREDITARY NEUROPATHIES

Topic: 02. Neuropathy

Max J. Hilz

Neurology, University of Erlangen-Nuremberg, Erlangen, DE

Abstract: Hereditary sensory and autonomic neuropathies (HSAN), Fabry disease, transthyretin-related familial amyloid polyneuropathy (TTR-FAP) and acute intermittent porphyria are examples of hereditary autonomic dysfunction. So far, eight HSANs have been classified. HSAN I presents in adulthood with prominent ulcers/mutilations of the lower extremities, stress-fractures, osteomyelitis, osteolysis, distal anhidrosis, low-normal nerve conduction velocities, impaired cold and heat pain-perception. Already during infancy, HSAN II-patients have acral anhidrosis, tonic pupils, eating/swallowing difficulties, constipation, apneic episodes, and develop deformed distal phalanges, paronychia, finger and plantar ulcers, unrecognized fractures and mutilating acropathy. They have severely impaired sensory-perception including vibratory and thermal perception, abnormal sensory but normal motor nerve conduction. Autosomal-recessive HSAN III (Familial Dysautonomia) afflicts Ashkenazi Jewish children, is characterized by diminished deep tendon reflexes, absent overflow tears, fungiform papillae of the tongue and axon flare response following intradermal histamine injection, pronounced central and peripheral autonomic dysregulation, including severe orthostatic hypotension (OH) and autonomic crises with excessive arterial hypertension, profuse sweating, skin blotching, puffy hands and behavioral abnormalities. Children with HSAN IV (Congenital Insensitivity to Pain with Anhidrosis) have episodic high fever with anhidrosis, pain-insensitivity, unnoticed injuries, multiple fractures, neuropathic joints and limb mutilation. Children with HSAN V have a selective loss of pain-perception. Autosomal-recessive HSAN VI is due to a DST (Dystonin) gene mutation, presents with neonatal hypotonia, poor feeding, respiratory problems, joint contractions, dysmorphic features, early death by age 2 and was reported in one Ashkenazi Jewish family. HSAN VII was reported in three patients with mutations in the SCN11A (Sodium Voltage-Gated Channel Alpha Subunit 11) gene which is also involved in Episodic Pain Syndrome. Patients have pain-insensitivity, multiple injuries, fractures, muscle-weakness, gastrointestinal-dysfunction and hyperhidrosis. Autosomal-recessive HSAN VIII is due to mutations in the PRDM12 gene (encoding a protein regulating pain-perception) and presents with pain- and temperature-insensitivity, self-mutilation, reduced sweating and tear-formation, absent corneal reflex, etc. Neurological manifestations of Fabry disease include severe lancinating pain, burning paraesthesias in the extremities, often triggered by temperature changes, anhidrosis, gastrointestinal-problems, vasomotor and cardiovascular autonomic dysfunction, baroreflex alteration, etc. Early diagnosis and enzyme replacement therapy can be beneficial. Autosomal-dominant TTR-FAP causes life-threatening autonomic dysfunction, particularly in early-onset patients, and length-dependent peripheral polyneuropathy with prominent small nerve fiber dysfunction causing impaired thermal and pain-perception, neuropathic-pain, allodynia, painless injuries, Charcot joints, carpal tunnel syndrome, and cardiac conduction failure. Patients have peripheral blood flow and blood pressure dysregulation with OH, altered heart rate variability, and cardiac arrhythmia resulting in syncope and sudden death. Gastrointestinal dysfunction includes constipation and/or diarrhea, nausea, vomiting. There may be bladder and erectile dysfunction. Autosomal-dominant acute intermittent porphyria due to haem-biosynthetic enzyme hydroxymethylbilane synthase deficiency, causes life-threatening acute attacks with autonomic symptoms, particularly painful-abdominal crises, peripheral-neuropathy progressing to respiratory paralysis, and cerebral involvement including psychosis, seizures or posterior reversible encephalopathy syndrome. Splanchnic autonomic dysfunction causes abdominal pain, with/without constipation or diarrhoea. There may be nausea and vomiting, arterial hypertension or OH, excessive sweating, bladder-sphincter dysfunction and other features of autonomic dysfunction. Autopsies show demyelination/axonal degeneration of vagus nerve and loss of sympathetic ganglion cells.

TC 3.4 / #66NEUROPATHIC MANIFESTATIONS IN PORPHYRIA

Topic: 02. Neuropathy

P. James B. Dyck

Mayo Clinic, Rochester, US

Background: Porphyrias are rare disorder of heme metabolism that presents in different types and each of the different types are characterized by a defect in an enzyme required for heme synthesis. These disorders can produce disturbances of multiple organ systems including the skin, liver, and central and peripheral nervous systems. Methods: We present information on the natural history, laboratory findings, evaluation and treatment of the neurological syndromes occurring in porphyria patients. Results: The types of porphyria that typically cause neurological disease are acute intermittent porphyria, hereditary coproporphyria and variegate porphyria, which are all autosomal dominant inherited conditions. The porphyrias generally present with attacks of illness. These attacks are characterized by neuropsychiatric symptoms with mood disorder or psychosis, motor predominant peripheral neuropathy (which often involve proximal and distal nerve segments and so resemble CIDP with severe weakness). Autonomic involvement (tachycardia, constipation, hypertension) and gastrointestinal disturbance (abdominal pain) are common, and (in the case of variegate porphyria and some hereditary coproporphyria) photosensitivity and cutaneous manifestations occur. Classically, there is a reddish discoloration of urine during an attack (after prolonged observation oxidation of porphyria precursors occurs). Attacks in porphyria can be induced by hormonal factors, nutritional factors, alcohol and use of drugs which induce the heme production pathway leading to an overabundance of heme ­precursors. An accurate diagnosis can be made through routine testing for overproduction of porphyria during an acute attack but this is more difficult in the quiescent phase. The most important factor in making the diagnosis is a high index of suspicion and an awareness of the diversity of clinical manifestations. DNA testing is available for the diagnosis. The best management of the disorder is through the prevention of acute attacks (avoidance of cytochrome P450-inducing agents and avoidance of periods of fasting) but intravenous hematin and glucose are helpful and should be considered during an acute attack. Introduction of new agents for the treatment of the porphyrias is in development. Conclusion: The neurological manifestation of porphyria generally present with attacks of neuropsychiatric symptoms, motor predominant peripheral neuropathy, abdominal pain and autonomic symptoms. They occur in patients with acute intermittent porphyria, hereditary coproporphyria and variegate porphyria. The diagnosis is often made by measuring excess porphyrins during an attack.

TC 4.1 / #1033EPIDEMIOLOGY AND DIFFERENTIAL DIAGNOSIS

Topic: 13. Pediatric

Guenther Bernert

Department Of Paediatrics, Kaiser Franz Joseph Hospital, Vienna, AT

Abstract not received.

TC 4.2 / #1034CLINICAL ASSESSMENT AND MUSCLE IMAGING: TECHNIQUES AND PITFALLS

Topic: 13. Pediatric

Presenter TBD

TC 4.3 / #1035FLOPPY INFANT SYNDROME AND THE ROLE OF “NEXT GEN”

Topic: 13. Pediatric

James J. Dowling

Hospital for Sick Children, Toronto, ON, CA

Abstract not received.

TC 4.4 / #858WHAT YOU MAY MISS WITHOUT EMG

Topic: 13. Pediatric

Matthew Pitt

Department Of Clinical Neurophysiology, Great Ormond Street Hospital for Children NHS Foundation Trust, London, GB

Abstract not received.

TC 5.1 / #45ENTRAPMENT SYNDROMES IN THE UPPER EXTREMITY – ELECTROPHYSIOLOGY

Topic: 06. Mononeuropathy

Christian Bischoff

Neurologische Gemeinschaftspraxis, München, DE

Abstract not received.

TC 5.2 / #163ENTRAPMENT SYNDROMES IN THE UPPER EXTREMITY – SONOGRAPHY

Topic: 06. Mononeuropathy

Nens Van Alfen

Radboudumc, Nijmegen, NL

Background: Nerve ultrasound is a proven technique for assessment of peripheral neuropathies, with excellent resolution in superficial tissue layers. In experienced hands it is more sensitive than MRI in detecting peripheral nerve pathologies (93% versus 67%) and has comparable specificity (86%). Ultrasound is a valuable adjunct to electrophysiology for assessing entrapment neuropathies. It has similar sensitivity for detecting entrapments as EMG, but both techniques complement eachother by adding different types of information about the lesion, so one can describe both form and function. Methods: For nerve size measurement, the workhorse is the transverse cross-sectional area (CSA). Because peripheral nerves can have different shapes, for example, round, oval, oblong, or triangular, depending on their anatomic location, transverse CSA is more reliable and reproducible than nerve diameter measurement, and is the most robust measure to confirm nerve pathology. The CSA should be measured within the hyperechoic epineurial rim that encircles the nerve fascicles. As it does not take much time to scan along the length of a nerve, it is strongly advised to scan the whole nerve during an exam, instead of just scanning a few predefined points along its course. Results: It is important to use the right reference value for the right patient. Ideally, a disease specific reference is available for the clinical question that needs to be answered, but if not, a population-based reference such as the p95 for CSA can also be used. Reference values for different nerves and populations are available in the literature. Conclusion: This talk will focus on the use of nerve ultrasound in entrapment syndromes of the upper extremities, including carpal tunnel syndrome, interosseus anterior syndrome, ulnar entrapment at the wrist and elbow, Martin Gruber anastomosis, radial nerve compression in the upper arm and supinator region, the incisura scapulae syndrome and neurogenic thoracic outlet syndrome. Case examples will show scanning technique, and diagnostic values will be presented where available.

TC 5.3 / #134ENTRAPMENT SYNDROMES IN THE LOWER EXTREMITY – ELECTROPHYSIOLOGY

Topic: 06. Mononeuropathy

Simon Podnar

University Medical Centre Ljubljana, Ljubljana, SI

Abstract not received.

TC 5.4 / #74ENTRAPMENT SYNDROMES IN THE LOWER EXTREMITY €

Topic: 06. Mononeuropathy

Alexander Grimm

Neurology, Tuebingen University Hospital, Tuebingen, DE

Abstract: Entrapment syndromes in the lower limbs are rare compared to those of the upper limbs. However, to accurately diagnose them is even more difficult. Gold standard of diagnosis are nerve conduction studies and electromyography, e.g. in peroneal or tibial palsy. Nevertheless, its sensitivity in tarsal tunnel syndrome or meralgia paresthetica is restricted. Second, as already known from ulnar nerve palsy or carpal tunnel syndrome, anatomical variants and secondary reasons of entrapment cannot be detected by electrophysiology. In these cases, nerve ultrasound has proven its validity. With high resolution probes ranging from 10 MHz (for femoral and ischiatic nerve) to 20 MHz (for sural or superficial peroneal nerve) we can accurately visualize the nerve and its fascicles. Thereby one can not only perform cross-sectional area measurements, but also elucidate fascicular anatomy and echointensity. Further, surrounding tissue can be demonstrated, e.g. vessels, tendons, muscles, scare tissue, ganglion cysts and others. E.g. in peroneal palsy, one might often find intra- or extraneural ganglia as reasons of pathology. Consequences, which might arise out of the imaging, are outstanding. In my talk, I want to go on further details concerning common entrapments as tarsal tunnel syndrome and fibular head palsy of the peroneal nerve, but also demonstrate some interesting and astonishing cases of rare nerve pathology, in which ultrasound could visualize the underlying pathology and prepare the way to surgical or conservative procedure. Methods: Nerve ultrasound, electrophysiology. Results: Examples of secondary reasons of entrapments. Conclusion: Nerve ultrasound might be a useful technique to further analyze mononeuropathies

TC 6.1 / #41A PATTERN RECOGNITION APPROACH TO PATIENTS WITH A SUSPECTED MYOPATHY

Topic: 01. Muscle

Richard J. Barohn

Neurology, University of Kansas Medical Center, Kansas City, KS, US

Abstract: Myopathies are disorders affecting the channel, structure, or metabolism of skeletal muscle. Myopathies can be distinguished by characteristic clinical and laboratory features. The pattern recognition approach involves asking key questions and then based on the answer putting the patient in one of the ten patterns. The key questions are: 1.) Does the patient have “negative” or “positive” symptoms and signs? 2.) What is the temporal time line? What is the distribution of weakness or stiffness? 4.) Are there triggering events for episodic weakness, pain, stiffness? 5.) Is there a family history of a myopathic disorder? 6.) Are there associated systematic symptoms/signs? The ten patterns are: 1.) Proximal “limb-girdle” Weakness 2.) Distal Weakness 3.) Proximal arm/distal leg weakness (Scapuloperoneal) 4.) Distal arm/proximal leg weakness 5.) Eyeball Weakness-Ptosis/ophthalmoplegia 6.) Prominent neck and trunk extensor weakness 7) Bulbar / diaphragm weakness 8.) Episodic pain, weakness, dark urine 9.) Episodic weakness delayed or unrelated to exercise 10.) Stiffness/decreased ability to relax. Once a pattern has been identified, the next step is determining what laboratory tests are needed.

TC 6.2 / #61LABORATORY APPROACH TO MUSCLE DISORDERS

Topic: 01. Muscle

Mazen Dimachkie

The University of Kansas Medical Center, Kansas City, US

Abstract not received.

TC 6.3 / #116GENETIC APPROACH TO MUSCLE DISORDERS

Topic: 01. Muscle

Tahseen Mozaffar

Uc Irvine-mda Als And Neuromuscular Center, University of California, Irvine, Orange, US

Abstract not received.

TC 6.4 / #1031APPROACH TO TRANSLATIONAL RESEARCH AND CLINICAL TRIALS IN MUSCLE DISEASE

Topic: 01. Muscle

Michael Hanna

UCL Institute Of Neurology, London, GB

Abstract not received.

TC 7.1 / #34HOW DO WE DISCUSS THE GENETIC IMPLICATIONS WITH ALS

Topic: 03. Motor Neurone

Ryuji Kaji

Tokushima University Graduate School of Medicine, JP

Abstract not received.

TC 7.2 / #96COGNITIVE CHANGE – RECOGNITION AND MANAGEMENT

Topic: 03. Motor Neurone

Albert Ludolph

Universitätsklinikum Ulm, Ulm, DE

Abstract not received.

TC 7.3 / #53BREAKING THE NEWS OF THE DIAGNOSIS

Topic: 03. Motor Neurone

Dorothée Lulé

University of Ulm, Ulm, DE

Abstract not received.

TC 7.4 / #108THE ROLE OF MULTIDISCIPLINARY CARE IN ALS

Topic: 03. Motor Neurone

Christopher Mcdermott

University Of Sheffield, Sheffield, US

Abstract not received.

TC 8.1 / #72MRI AND US IN THE DIAGNOSIS OF NEUROPATHY

Topic: 02. Neuropathy

Stephan Goedee

Brain Centre Rudolph Magnus, Umc Utrecht, Utrecht, NL

Background: Diagnosis of chronic inflammatory neuropathies rely heavily on electrodiagnosis. In order to demonstrate sufficient proof of demyelination, elaborate studies are needed since the electrodiagnostic findings of demyelination are focal and patchy distributed. Neuro-imaging may complement this, as even extensive EDX studies may fail to identify these potentially treatable neuropathies. MRI imaging has been aknowledged as an important adjunctive diagnostic tool in the current sets of diagnostic criteria. More recently, ultrasound has gained importance as a powerful and practical bedside tool, that allows reliable identification of chronic inflammatory neuropathies. Methods: The role of MRI and ultrasound imaging in the diagnosis of neuropathy wil be discussed, including their part in complementing electrodiagnosis in the appropriate cinical context. Results: Standardization of MRI protocols, including diagnostically relevant sequences (T2/DIXON) and parameters (enlargment, T2 hyperintense signal nerve(root)), and recent developments such as DTI imaging and neurography will be discussed in detail. Ultrasound evaluation and diagnosis of chronic inflammatory neuropathies will also demonstrated in detail, including proposed scoring systems and a practical sonographic protocol en prediction rule.

Conclusion: MRI and ultrasound imaging are important emerging diagnostic tools in neuromuscular practice, that can aid subtantially in the distinction of potentially treatable neuropathies.

TC 8.2 / #92SKIN BIOPSY: NOT JUST FOR DIAGNOSIS

Topic: 02. Neuropathy

Grazia Devigili

Fondazione Irccs Istituto Neurologico Carlo Besta, Milan, IT

Abstract not received.

TC 8.3 / #112OUTCOME MEASURES IN NEUROPATHY

Topic: 02. Neuropathy

Ingemar Merkies

Department Of Neurology, Maastricht University Medical Center, Maastricht, NL

Abstract not received.

TC 8.4 / #166ROLE OF ELECTROPHYSIOLOGY IN THE CHARACTERIZATION AND DIAGNOSIS OF NEUROPATHIES: NEW INSIGHTS

Topic: 02. Neuropathy

Peter Van Den Bergh

Neuromuscular Reference Centre, University Hospital Saint-Luc, Brussels, BE

Abstract: Electrophysiology plays a crucial role in the characterization and diagnosis of peripheral neuropathies. It provides insight in the type and mechanism of peripheral neuropathy by giving information on the spatial pattern (generalized, multifocal, focal), the fibre type involved (motor, sensory), pathology (axonal, demyelinating), and the severity and time course (acute, ongoing, chronic). Electrophysiological studies are key in the early detection and characterization of inflammatory demyelinating neuropathies and in differentiating these from ­primary axonal neuropathies. Inflammatory demyelinating neuropathies constitute a significant proportion of the acquired peripheral neuropathies. They include Guillain-Barré syndrome (GBS), chronic inflammatory demyelinating polyradiculoneuropathy (CIDP), multifocal motor neuropathy (MMN), multifocal demyelinating neuropathy with persistent conduction block (Lewis-Sumner syndrome), and paraproteinemic neuropathies. A proper diagnosis as early as possible is very important because timely immune treatment can largely reduce morbidity and disability. The diagnosis is based on a constellation of clinical and laboratory features, including electrophysiological studies, spinal fluid examination, and in selected cases serological studies and peripheral nerve biopsy. In CIDP, electrophysiological criteria for demyelination are designed to exclude abnormalities that can be explained by axonal degeneration (Eur J Neurol 2010). Therefore, lesser degrees of demyelination cannot be defined with certainty. Optimised electrophysiological criteria are capable, however, to support the diagnosis with different levels of probability (possible, probable, definite) in the very large majority of cases. In GBS, much effort has gone into developing criteria which can distinguish axonal and demyelinating subtypes. The discovery of reversible conduction failure (RCF) has led to the concept of nodopathy/paranodopathy, where conduction slowing and conduction block are due to the immune attack mainly at the nodal axolemma level. There is no actual demyelinisation as defined pathologically and if the immune attack continues, conduction failure may not reverse and axonal degeneration will ensue. Recent electrophysiological studies support this pathophysiological mechanism and show that the dichotomous distinction between axonal and demyelinating in GBS is not tenable (Muscle nerve, 2018).

TC 9.1 / #1021REQUIREMENTS AND PITFALLS FOR SMALL MOLECULES

Topic: 01. Muscle

Mike Kelly

Rush University Medical Center, Chicago, US

Abstract not received.

TC 9.2 / #1022REQUIREMENTS AND PITFALLS FOR GENE THERAPY

Topic: 01. Muscle

Isabelle Richard

INTEGRARE, Généthon, Inserm, Univ Evry, Université Paris-Saclay, Evry, FR

Abstract not received.

TC 9.3 / #1023REQUIREMENTS AND PITFALLS FOR STEM CELLS

Topic: 01. Muscle

Miranda Grounds

University of Western Australia, Perth, AU

Abstract not received.

TC 9.4 / #1059PRECLINICAL TRIAL DESIGN

Topic: 01. Muscle

Annamaria De Luca

Dep Pharmacy & Drug Sciences, University of Bari, Bari, IT

Abstract not received.

TC 9.5 / #1024STATISTICAL POWER EVALUATION

Topic: 01. Muscle

Heather Gordish-Dressman

George Washington University School of Medicine and Health Sciences, Washington, DC, US

Abstract not received.

TC 9.6 / #732DATA INTERPRETATION, TRANSLATIONAL MEANING

Topic: 01. Muscle

Annamaria De Luca

Dep Pharmacy & Drug Sciences, University of Bari, Bari, IT

Abstract not received.

TC 9.7 / #1036REGULATORY REQUIREMENTS

Topic: 01. Muscle

Didier Caizergues

Genethon, Paris, FR

TC 9.8 / #1020CLINICAL TRIAL READINESS

Topic: 01. Muscle

Kathryn R. Wagner

The Johns Hopkins School of Medicine, Baltimore, MD, US

Abstract not received.

TC 9.9 / #1025CARE ASPECTS IN CLINICAL TRIAL PLANNING

Topic: 01. Muscle

Anna Mayhew

Newcastle University, Newcastle Upon Tyne, GB

Abstract not received.

TC 9.10 / #1026PATIENT PERSPECTIVE

Topic: 01. Muscle

Elizabeth Vroom

Duchenne Parent Project Netherlands, Veenendaal, NL

Abstract not received.

TC 9.11 / #1027BUSINESS MODEL

Topic: 01. Muscle

Cristina Csimma

Csimma Llc, Lincoln, US

Abstract not received.

OA 1.1 / #129STEM CELLS AS TOOLS FOR RESEARCH AND THERAPY IN NEUROMUSCULAR DISORDERS

Topic: Overarching Topic

Rita Perlingeiro

University of Minnesota, Minneapolis, US

Abstract not received.

OA 1.2 / #176STEM CELLS IN MUSCULAR DYSTROPHIES

Topic: Overarching Topic

Mayana Zatz

University Of São Paulo, São Paulo, BR

Abstract not received.

OA 1.3 / #83STEM CELLS IN ALS

Topic: Overarching Topic

Dimitrios Karussis

Hadassah Hmo, Jerusalem, IL

Abstract not received.

OA 2.1 / #60NEUROMUSCULAR DISORDERS WITH DYSPHAGIA: AN OUTLINE

Topic: Overarching Topic

Marianne De Visser

Department Of Neurology, Academic Medical Centre, Amsterdam, NL

Abstract not received.

OA 2.2 / #39HOW TO ASSESS AND MANAGE DYSPHAGIA

Topic: Overarching Topic

Zohar Argov

Hebrew University of Jerusalem EKMD, Jerusalem, IL

Background: The topic of dysphagia management and swallowing assessment receives low attention in the neuromuscular field. The main risks of dysphagia are reduced food intake and recurrent aspirations. Treatment trials in at least two muscle disorders (OPMD and sIBM) looked at dysphagia as an outcome, but there are no agreed upon clinical and investigational guidelines. Aims To review tests that can serve as treatment assessments for either clinical follow up or therapy trials and to present the main dysphagia management modalities. Observations 1. There are several patient reported outcome measures that were validated for dysphagia (e.g. EAT10 SWAL-QoL). 2. Drinking tests include the ‘classical’ 80 cc cold water test (useful and easy to use bedside test that has served as an outcome in OPMD trials). Its main shortcomings are test-test variability and lack of strong correlation with aspiration risk. Using different fluid consistencies may resolve these issues. 3. Videofluoscopy (VFS) of barium swallow using an 8 point penetration- aspiration scale has been practiced in neuromuscular and other neurological conditions. It was validated in some disorders, its main deficiency is the semi quantitative nature of the test and the inconsistency between swallow attempts. VFS can monitor and quantify the several stages of the swallowing process. It requires high technical skills and dedicated equipment. Radionuclide swallow test has been developed and is less technically complicated yet limited data are available. 4. Dysphagia management includes: change of diet and eating habits, mechanical dilatation (which usually needs to be repeated), Botox injection (minimal observations), cricopharyngeal myotomy (needs a very experienced surgeon using the right technique for prolonged effects) and feeding tubes. Conclusion: Neuromuscular experts should become more familiar with dysphagia assessment and management. New therapeutic trials, now being planned for several conditions, mandate the development of clinical and investigational guidelines.

OA 2.3 / #122ETHICAL ISSUES IN DYSPHAGIA TREATMENTS

Topic: 03. Motor Neurone

David J. Oliver

Tizard Centre, University of Kent, Canterbury, GB

Background: Dysphagia is a common symptom for people with neuromuscular disease – up to 90% in ALS. It is a distressing symptom for patients who face frustration at mealtimes, reduced nutrition, anxiety and fear of starvation, increased risks of aspiration and drooling. Moreover it is often a family issues as family carers experience the same emotional reaction and fears. Methods: A review of the literature has been undertaken. Results: There are several aspects of managing the symptoms – speech and language assessment allowing nutrition and hydration to be continued by careful feeding of foods with the most appropriate consistency; careful feeding by hand at risk, acknowledging the risk of aspiration but allowing the patient to retain the taste and activity of eating; consideration of enteral feeding, by naso-gastric tube or gastrostomy; intravenous or subcutaneous hydration to allow hydration. However there are many ethical issues raised in the assessment and discussion and management of these patients. In particular: - Whether to consider and use at risk feeding by hand – this may be appreciated by the patient and family but there is a risk of aspiration and possible deterioration and death - Whether to consider and discuss enteral feeding. Nasogastric tubes have a small risk of causing harm, and there is an appreciable morbidity and mortality of the placement of a gastrostomy. This may need to be considered earlier in the patient’s progression, as deterioration in the respiratory function may be a factor with greater importance for the safety of the procedure. - Whether to with-hold treatment – either the procedure such as gastrostomy, or the use of feeds and hydration – or withdraw treatment as the patient deteriorates and comes towards the end of life. - In some countries, where assisted dying is permitted, dysphagia may be one of the symptoms that can lead to patients requesting a hastened death, from physician assisted suicide or euthanasia. Conclusion: These issues are complex and require careful assessment and communication within teams, and closely involving patient and family.

OA 3.1 / #37IMPACT AND EVOLUTION OF COGNITIVE IMPAIRMENT IN MUSCULAR DYSTROPHIES

Topic: 01. Muscle

Corrado Angelini

Irccs S.Camillo Hospital, Venice, IT

Background: Cognitive involvement is an important feature in several types of muscular dystrophies such as myotonic dystrophy (DM1) or limb girdle dystrophies (LGMD) and needs to be addressed by physicians. DM1 is a multisystemic disease characterized by muscle, heart and CNS dysfunction. There are at least five sub-types of DM1 classified as congenital (onset at birth),childhood (1-10 years),juvenile (10-20 years), adult (20-40 years),late onset(>40 years). Methods: A literature review was performed using the following keywords: DM1, LGMD, cognitive impairment, MRI and white matter abnormalities. Results: Congenital DM1 presents at birth with polyhydramnios, reduced fetal movements; after birth the child has severe weakness, muscle hypotonia, respiratory involvement. There is then a gradual improvement although these children present cognitive deficit and learning abnormalities. Apathy seems to be associated with impaired cognitive status, fatigue, motor disability. Fatigue is a prominent sign and a major complaint in DM1. Besides cognitive and behavioural features reduced awareness of disease is defined as “anosognosia”, i.e.lack of awareness of disease burden can be studied by correlating patient’s perception of disease status to caregiver observation. A significant number of brain imaging studies were done in DM1. In young/adult patients a significant structural alteration is present in white matter with relevant abnormalities in frontal, temporo-parietal polar and occipital regions. Atrophy of cerebral grey matter was also observed suggesting a global network and neuronal impairment. In congenital DM1 hydrocephalus might be present on MRI. The juvenile form of DM1 with age of onset after 10 years has under-recognized school learning problems beside the classical signs of grip myotonia distal muscle weakness and atrophy,. In adult onset DM1 nocturnal episodes of natural apnoea and day-time sleepness are common. Loss of serotonin-containing neurons might be in relation to hypersomnia. In late onset forms there are behavioural abnormalities that range from inappropriate behaviour to depression. In DM1 the evolution of cognitive and white matter abnormalities are a matter of research seem to progress with time and studies report after 5-9 years a progressive dysfunction for verbal memory, attention tasks and visual-spatial construction. White matter abnormality seems to progress although with variable extent on tested patients and families. Few longitudinal studies have attempted to correlate MRI imaging with neuropsychological changes, further research on longitudinal DM1 cohorts are needed. In LGMD due to a dystroglycan involvement (LGMD 2I)important cognitive deficits and visual-spatial construction difficulties are present. In an observational study we found several changes in nine LGMD 2I patients who underwent brain MRI scanning: four showed non-specific white matter abnormalities; two showed moderate ventriculomegaly; three showed mild enlargement of subarachnoid spaces; cerebellar atrophy was present in one patient. Conclusion: These observations point-out to the need for of developing clinical protocols for LGMD and DM1 patients that address the CNS dysfunction and quality of life. Physician should remain vigilant about personal hygiene, child neglect, financial needs in muscular dystrophy patients. The use of drugs such as modafinil might help to keep DM1 patients in a better vigilance status. Behaviour cognitive abnormalities might be approached both with drugs or individual cognitive strategies.

OA 3.2 / #57BRAIN IMAGING TECHNIQUES FOR THE NEUROMUSCULAR PATIENTS

Topic: Overarching Topic

Nicola De Stefano

University Of Siena, Siena, IT

Abstract not received.

OA 3.3 / #62THE GAP BETWEEN COGNITIVE ASSESSMENT AND BRAIN IMAGING: LESSONS FROM DMD

Topic: 01. Muscle

Nathalie Doorenweerd

C.j. Gorter Center For High Field Mri, Leiden University Medical Center, Leiden, NL

Background: Cognitive assessments have demonstrated cognitive impairment, learning and behaviour difficulties and/or increased comorbidity of neuropsychiatric disorders in several different neuromuscular dystrophies. Neuroimaging has been used to elucidate the development of the healthy brain throughout a person’s lifespan and its relation to cognitive function. However, when applied to Duchenne muscular dystrophy patients, who have a range of cognitive abilities and also a range of quantified structural cerebral alterations, the relationship between the two is anything but straightforward. Methods: On a group level, the power of imaging to detect patterns in altered structure or metabolism that point towards the involvement of specific mechanistic pathways is remarkable. When the function of a protein or gene within the brain is largely unknown, this is an important relationship. For an individual assessment, however, it is important to note the variability in absolute values of quantitative MRI measures, and the partial overlap with values associated with healthy controls. Such variability is not restricted to neuromuscular dystrophies, but rather a common theme in neuroscience. Results: For example, cerebral atrophy has been reported in cognitively-normal Alzheimer’s patients, and a patient with severe autism can have a normal-appearing anatomical MRI. Conclusion: To discuss the gap between cognitive assessment and brain imaging, we will provide examples from our own research into the brain involvement in Duchenne muscular dystrophy. We will also review the recent literature and show examples from Myotonic Dystrophy and specific Congenital muscular dystrophies that highlight the wide spectrum of both cognitive ability and MRI abnormalities.

ID:840NEUROPATHIES IN AFRICA

Topic: 02. Neuropathy

Riadh Gouider

Neurology, Razi Hospital, Tunis, TN

Background: Systematic studies about peripheral neuropathies (PN) in Africa are lacking. PN are common and their incidence was estimated at 2.1 to 31 per thousand in this continent. Methods: We reviewed epidemiology and etiologies of PN in Africa. We searched Medline, Scopus and science direct using the following search terms “Neuropathies”, “Africa”, “epidemiology” and “etiology”. Results: Diabetic neuropathy, one of the leading causes of PN worldwide, is becoming an increasing burden in African countries because of the poor quality of diabetes control and care. Conversely, etiologies of neuromuscular disorders vary considerably according to the African region considered. In Sub-Saharan Africa, infectious diseases are very prevalent causes. Neuropathies related to HIV, are frequently observed in South of Africa. They may be due to the direct effects of HIV, exposure to antiretroviral medications, advanced immune suppression and/or comorbid tuberculosis infection and exposure to antituberculosis medications. On another hand, leprosy is one of the main causes of PN in endemic countries such as in east and tropical Africa. Neuropathy is often clinically silent in its evolution making early diagnosis exceptionally challenging. Elsewhere, both deficiency in micronutrients related to malnutrition and toxin ingestion are mostly represented in western Africa. The occurrence of tropical ataxic neuropathy (TAN), due to the ingestion of poorly processed cassava, continues at a lesser prevalence than reported thirty years ago.Finally, hereditary neuropathies, especially Autosomal recessive forms of Charcot-Marie-Tooth disease (AR CMT) are frequent in North Africa because of high consanguinity in this region. They are characterized by an early onset, and quiet severe phenotype.Genetic analysis of large African families allowed discovering many new genes mutations such as LMNA/C gene mutations with variable phenotypes (CMT or Muscular dystrophy) and MTMR13 gene mutations with some clinical and histological characteristics as glaucoma with focally folded myelin sheaths aspect. Conclusion: Given this particular distribution of PN etiologies among regions in Africa, it is difficult to draw a diagnostic strategy without considering the patient origin. Lack of neurologists in some countries and of tools of diagnosis such an EMG in several countries makes the situation even more challenging.Although the handicap generated by such diseases, many patients still not accessing the level of health and social care services that could improve their health related quality of life.

ID:857VIRTUAL SESSION: HIV-ASSOCIATED NEUROMUSCULAR MANIFESTATIONS: EXPERIENCE FROM CAPE TOWN

Topic: 02. Neuropathy

Jeannine M. Heckmann, Kathleen J. Bateman, Melody Asukile, Sarvani Chetty, Herman Ekea, Saara Neshuku

Medicine (neurology), University of Cape Town, Cape Town, ZA

Background: HIV infection can affect multiple levels of the nervous system at the same time and at all stages of infection. This also applies to the neuromuscular system. South Africa remains a high prevalence region with >5 million people on government sponsored antiretroviral treatment (ART) programs. Methods: The aim of this virtual session is to present interesting cases which we have encountered in our resource-constrained, high HIV prevalence setting. In addition, we invite discussion of more commonly encountered management issues. Results: The commonest manifestation, distal sensory polyneuropathy shows increasing incidence with advancing age, despite effective antiretroviral therapy, and has been shown to associate with increasing functional disability when compared to those with one or less neuropathic signs. Acute inflammatory demyelinating polyradiculoneuropathy (AIDP) occur in patients with CD4 counts between 45 and 652 cells/mm³ and have a similar response to therapy compared to those with HIV-unaffected AIDP. Mimics of AIDP in our setting have included tuberculous lumbosacral radiculopathy, which may manifest as an immune reconstitution syndrome, diffuse infiltrative lymphocytic syndrome (DILS), and, rarely, syphilitic meningitis with radiculopathy. Since the earlier roll-out of ART, lower motor neuron syndromes are less frequently encountered including the segmental inflammatory motor radiculopathy, lymphomatous or cytomegalovirus radiculopathies. HIV-associated chronic inflammatory demyelinating polyradiculoneuropathy responds well overall to treatment with corticosteroids and antiviral agents, and may be monophasic, but second-line treatment may be required in the minority. Subacute HIV-associated “motor neuron disease” remains very rare. Myasthenia gravis is seen in patients infected with HIV, presenting either before or after HIV infection, but these cases are treated similarly to those without HIV. Several cases of HIV-associated inflammatory myopathy have been encountered and mostly respond to immune-therapy and ART. Although uncommon, we will also discuss a sporadic steroid-responsive, but steroid-dependent nemaline myositis. Conclusion: We describe a range of neuromuscular manifestations associated with HIV-infection. As has been observed in first world countries, the earlier initiation of ART has resulted in an overall decline in neuromuscular complications associated with more advanced HIV-infection.

ID:321WHY OPT FOR AN ENMC WORKSHOP?

Topic: European Neuromuscular Centre (ENMC)

George W. Padberg¹, Baziel Van Engelen²

¹Dep. Of Neurology, Radboud University Medical Center, Nijmegen, NL

Abstract not received.

ID:322THE IMPACT OF 25 YEARS ENMC WORKSHOPS

Topic: European Neuromuscular Centre (ENMC)

Raffaella Willmann

Enmc Executive Committee, Swiss Foundation for Research on Muscle Diseases, Zürich, CH

Background: The European NeuroMuscular Centre (ENMC) was constituted in 1992 to encourage and facilitate collaborative research in Europe on neuromuscular disorders (NMD) to contribute to the eradication of these diseases. During its 25 years of activity, the ENMC established a network of more than 2500 clinicians and scientists from over 65 different countries and hosted/organized 236 workshops. Discussion topics, agreements and deliverables of the workshops have been regularly summarised in scientific reports, published on Neuromuscular Disorders and actively cited in the scientific community. During its first 10 years of activity (with about 100 workshop sponsored), the ENMC contributed to the achievement of several goals, such as the creation of several disease-specific consortia, publication of books on diagnostic criteria, definition of clinical and molecular features of NMD. These activities reflected the most urgent needs of the NMD community, but then it was also felt that future policies had to include other initiatives to improve neuromuscular cure and care (Rüdel et al., Neuromusc. Dis., 2000, 10:75-82; Emery et al., Clinical Medicine, 2001, 1:200-202). Particularly, the founders encouraged the ENMC to engage in additional activities in order to foster the development of protocols for therapeutic trials and management studies, to promote training and to establish new cooperative networks for clinical trials. Therefore, while continuing its support to the NMD community through the financing of focused workshops, the ENMC also invested in the promotion of new initiatives, such as the “Clinical Trial Network”, aimed at providing the evidence and guidance for developing treatments and for management of NMD. This activity contributed to set the ground for the TREAT-NMD network, funded from 2007 to 2011 within the EU FP6 Health program, to which ENMC was part, now continuing as Treat-NMD Alliance (www.treat-nmd.eu). In the most recent years, the ENMC refreshed the structure of its sponsored workshops, paying particular attention to the value of involving people affected by neuromuscular conditions in every meeting. Giving voice to patients often resulted in important contributions during the discussion and is now an essential component of each workshop’s program. In addition, the ENMC started to actively involve young researchers and clinicians in the workshops, thus contributing to the development of the next generation of professionals. Methods: To evaluate the long-term vision of improving quality of life of people affected by NMD, the ENMC conducted a survey and a detailed analysis of workshop topics and citation index in the last 25 years. Moreover, it retrospectively monitored the implementation in the NMD community of agreements, decisions and other deliverables derived from a recent five-years-cohort of ENMC workshops. Results: The evaluation identified and quantified pitfalls and challenges in fulfilling deliverables and goals, highlighting possible reasons for success or for delays or failure in translating the workshop outcomes into actions to improve patients’ quality of life. Conclusion: These data will be presented in occasion of the ENMC 25^th anniversary symposium at the ICNMD meeting and will be used in future to support effective and constructive workshops for implementable research progresses.

ID:323CHARCOT-MARIE-TOOTH DISEASE AT ENMC WORKSHOPS

Topic: European Neuromuscular Centre (ENMC)

Mary Reilly

Institue Of Neurology, London, GB

Abstract: Charcot Marie Tooth disease (CMT) is the commonest inherited neuromuscular disorder affecting 1 in 2,500 people. It characteristically starts in the first two decades of life with distal wasting, weakness, foot deformity and sensory loss and progresses at different rates depending on the subtype. There are over 100 causative genes but in northern Europe, UK and the US about 50% of patients have the common CMT1A genotype due to a 1.4 megabase duplication of chromosome 17 containing the peripheral myelin protein 22 gene (PMP22). This is also the commonest genotype worldwide. The chromosome 17 duplication was the first causative gene to be identified for CMT in 1991 and the 25 years since then has seen an explosion in gene identification followed by natural history studies, outcome measure development, guideline development and clinical trials. Since it was founded in 1992, the ENMC has played a crucial role in all of the above developments in CMT and has enabled collaborative research and progress which would have been much more difficult without the CMT ENMC workshops. The ENMC has not only brought European researchers and patients together but it has also facilitated the inclusion of people from further afield including the US and Australia when beneficial. The ENMC was ahead of its time by truly giving patients a voice in research and developing therapies for their disease. The initial ENMC meetings facilitated gene discovery by enabling carefully phenotyped family details to be gathered, discussed and combined for further genetic studies. Many new types of CMT were identified in this way. In the early 2000s pre clinical studies suggested that ascorbic acid might be a beneficial therapy for CMT1A. A very important ENMC meeting on CMT1A in 2005 allowed us to look at the evidence and critically to agree a protocol for trials. This meant all three of the 2 year international trials (French, UK/Italian and US) used the same primary outcome measure (CMTNS) which allowed all the results to eventually be considered together in a Cochrane review. Although all the trials were negative, I suspect this may have been the first time all trials of a new therapy used an identical primary outcome measure. Following this a further ENMC meeting in 2009 to look critically at our outcome measures resulted in both agreeing modifications to the adult measure (CMTNS) and laid the grounds for developing the paediatric outcome measure (CMTPeds), which has since been published and validated. Most recently in response to the lack of evidence for the varying types of foot surgery for CMT, an ENMC meeting in 2016 resulted in the publication of preliminary guidelines and the identification of areas needing further research. CMT clinicians, researchers and most of all patients owe a lot to the ENMC.

ID:324ENMC TRANSLATIONAL RESEARCH WORKSHOP

Topic: European Neuromuscular Centre (ENMC)

Kanneboyina Nagaraju

School Of Pharmacy And Pharmaceutical Sciences, SUNY-Binghamton University, Binghamton, NY, US

Background: There are very few specific therapies for neuromuscular diseases (NMD) despite significant basic sciences advances for the last 2-3 decades in this field. There are several reasons why basic science research failed to translate into new therapies for these disorders. One of the reasons is the lack of rigor and reproducibility of preclinical research in animal models of these diseases. One way to address this issue is to bring various stakeholders such as basic scientists, pre-clinical scientists, journal editors, clinicians, clinical trialists, industry, funding agencies, parent groups, and regulatory agencies to formulate guidelines that enhance reproducibility of preclinical animal research in NMDs. Methods: The ENMC workshop assembled 27 stakeholder representatives from seven different countries (USA, Italy, Switzerland, Netherlands, Belgium, United Kingdom, Australia) in Heemskerk in the Netherlands, on the weekend of the 10th– 11th of February 2017 to help finalize a plan to guarantee quality in translational research for neuromuscular diseases. Results: After extensive one and half day discussions the participants agreed that there are significant gaps in a) understanding translational research both among basic scientists and clinicians, b) evaluating grant applications by funding agencies and c) publication of peer reviewed translational research in journals. Workshop participants agreed to 1) organize a teaching workshop for clinicians and basic researchers interested in the planning and conduct of NMD clinical trials, 2) promote rigorous scientific evaluation of grant applications and to enforce the requirement for strong if possible independent validation of pre-clinical data before human clinical trials and 3) encourage journal editors to implement the ARRIVE guidelines and publish negative data. Conclusion: This workshop for the first time ­highlighted that promoting robust and reproducible translational research would enhance success of future treatments for NMDs. By facilitating these discussions and by offering the adequate format, ENMC greatly contributed and continues to contribute to the progress in research for neuromuscular diseases.

ID:326THE POSITION OF NEUROMUSCULAR PATIENTS IN SHARED DECISION MAKING

Topic: European Neuromuscular Centre (ENMC)

Anna Ambrosini

Research And Development, Fondazione Telethon, Milan, IT

Background: In occasion of its 25^th anniversary, the European Neuromuscular Centre (ENMC) organised a special workshop involving 45 participants from 15 countries, representing patients and patient organizations, health professionals, clinical researchers, regulatory agencies, social scientists, ethicists and industry. Aim of the meeting was the assessment of patient participation in research and care options for neuromuscular diseases, using Shared Decision Making (SDM) as a tool to drive discussions. Methods: SDM has been defined as “an approach where clinicians and patients share the best available evidence when faced with the task of making decisions, and where patients are supported to consider options, to achieve informed preferences”. In practice, SDM applies to the communication between a health professional and a patient about the options of prevention, screening, diagnostic tests and treatment, including the option of not intervening; the goals of the method being better-informed patients, more confidence in and satisfaction about the treatment, and more compliance. Results: During the meeting, the SDM concept was discussed at first in relation to its natural field of application, the bilateral interaction between patients and their clinician. Different moments of the delivery of care were addressed, from genetic screening and diagnosis, to the management of transition from child to adult, and implementation of standards of care that have major impact on daily life. Then, the participants borrowed the SDM concepts to investigate the ­position of patient/patient organizations with respect to their level of participation in decision processes dealing with clinical research, in particular, in relation to patient registries and biobanks, research on quality of life, clinical trials design, and regulatory and consenting processes. Expectations are that, thanks to a better knowledge and empowerment, the patient community is able to take an increasingly decisive role in clinical trials, dissemination, and relationship with pharmaceutical industry and public health institutions. For each field addressed during the workshop, working groups including both professionals and patient representatives analysed: i) opportunities and limitations of patient participation as well as wishes of the patient community; ii) positive and negative examples and availability of best practices; iii) feasibility of implementation of a greater patient involvement; iv) next steps to be taken. In the end, some common features among all topics became evident. In order to be active partners, patients need to be properly informed, hence formation is key. However, education and training concern all stakeholders, with coaching and proficient communication about wishes and challenges of implementing patients’ participation in the various areas addressed. The roles and preferences of all stakeholders should be made more explicit. Moreover, structural changes are necessary in order to include patient representatives/organizations in advisory boards, ethics committees and in every stage of clinical trials. Conclusion: Overall, the active inclusion of patients in delivery of care and research processes requires changing attitudes, and therefore, ambassadors are needed who inspire and empower others about the benefits of patients’ participation. It was emphasized that exchange at the European level is also needed. An ENMC white paper will identify more specific actions and goals for the six topics ­discussed.

PS1Group1-001 / #342A FAMILY-BASED STUDY INTO PENETRANCE IN FACIOSCAPULOHUMERAL MUSCULAR DYSTROPHY TYPE 1

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Mariëlle Wohlgemuth¹, Richard J. Lemmers², Marianne A. Jonker³, Elly L. Van Der Kooi⁴, Corinne G. Horlings⁵, Baziel G. Van Engelen⁵, Silvere M. Van Der Maarel², George W. Padberg⁶, Nicol C. Voermans⁵

¹Neurology, Radboud University Medical Center, Nijmegen, NL;²Human Genetics, leiden University medical Center, Leiden, NL;³Health Sciences, Radboud University Medical Center, Nijmegen, NL;⁴medical center leeuwarden, leeuwarden, NL;⁵Neurology, Radboud University Medical Center, Nijmegen, NL;⁶Dep. Of Neurology, Radboud University Medical Center, Nijmegen, NL

Background: Objective: An observational cross-sectional study in a national FSHD expertise center to estimate the penetrance of facioscapulohumeral muscular dystrophy (FSHD)1 and to evaluate phenotype-genotype correlations. Methods: Ten FSHD1 probands carrying 4-9 D4Z4 units alleles and 140 relatives were examined. All 150 subjects were genetically characterized, including D4Z4 methylation levels in the mutation carriers. Mutation carriers were classified as 1) symptomatic: with symptoms of muscle weakness on history and muscle FSHD signs on examination; 2) asymptomatic: without symptoms of muscle weakness but with muscle FSHD signs on examination; and 3) non-penetrant: without symptoms of muscle weakness on history and without muscle FSHD signs on examination. We assessed the relationship between age-corrected clinical severity score and repeat size, sex and D4Z4 methylation levels. Results: The maximum likelihood estimates of symptomatic and those of symptomatic plus asymptomatic FSHD showed that penetrance depends on repeat size and increases until late adulthood. We observed many asymptomatic carriers with subtle facial weakness with or without mild shoulder girdle weakness (25% (17/69)). Non-penetrance was observed less frequently than in recent population studies (17% (12/69)), and most asymptomatic patients reported some shoulder pain. Methylation tended to be lower in moderately to severely affected mutation carriers with longer repeats. Conclusion: This family-based study detected a lower overall non-penetrance than previously observed, probably due to many asymptomatic mutation carriers identified by careful examination of facial and shoulder muscles. The recognition of asymptomatic mutation carriers is essential for selection of participants for future trials, and the likelihood estimates are helpful in counseling.

PS1Group1-002 / #482EVALUATING THE USEFULNESS OF NEW LINE IMMUNOASSAYS FOR MYOSITIS ANTIBODIES IN CLINICAL PRACTICE: A RETROSPECTIVE STUDY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Federica Montagnese¹, Haris Babacic², Peter Eichhorn³, Benedikt Schoser⁴

¹Neurology, Friedrich Baur Institut LMU, Munich, DE;²Neurology, Friedrich Baur Institut LMU, Munich, DE;³Institute Of Laboratory Medicine, Ludwig Maximilian University, Munich, DE;⁴Friedrich-baur Institute, Departement Of Neurology, Ludwigs-Maximilians University of Munich, Munich, DE

Background: The diagnosis of idiopathic inflammatory myopathies (IIM) relies on clinical and histological (inflammatory infiltrates on muscle biopsy) criteria. However, an increasing number of myositis-associated (MAA) and myositis-specific antibodies (MSA) are being detected in sera of IIM patients and are considered useful diagnostic biomarkers. New line immunoassays are nowadays widely used for MSA/MAA detection though some concerns on their reliability arise due to limited validation in comparison with the gold standard immunoprecipitation. Furthermore, the disease specificity of these antibodies has been mainly studied in myositis patients and data on screening in control patients are often limited. The aim of our study was to assess the accuracy of MSA and MAA in diagnosing IIM in our large cohort of patients. Methods: We have retrospectively analysed the sera of patients that between 2014 and 2017 have been tested for myositis antibodies. The “Euroline: myositis 16 Ag” Kit by EUROIMMUN has been used to assess the presence of the following MSA/MAA: Mi-2alpha,Mi-2beta,TIF1gamma,MDA5,NXP2,SAE1,Ku,PM-Scl100,PM-Scl75,Jo-1,SRP,PL-7,PL-12,EJ,OJ,Ro-52. Additional clinical data as symptoms at onset, CK, muscle biopsy and conclusive diagnosis were also analysed. We have calculated the sensitivity (Se), specificity (Sp), positive/negative predictive values (PPV, NPV) and positive/negative likelihood ratios (LR+, LR-) for MSA and MAA as well as group as for the single antibodies. Results: 1232 patients (1727 serum samples) were identified. Muscle biopsy was performed in 583 patients (47%). Conclusive diagnoses were: myopathy (n=356), IIM (n=148), no evidence of neuromuscular diseases (n=587) and other neuromuscular diseases (e.g. ALS, neuropathies; n=141). The overall Sp was for MSA 95% and for MAA 89%, whereas the Se was 21% and 22% for MSA and MAA respectively. Further analyses were performed considering only individuals who underwent muscle biopsy as gold standard for IIM diagnosis. This group comprised 134 myositis and 446 controls (55% myopathy, 11% other neuromuscular disease and 35% no neuromuscular diseases). In this subgroup of patients the Se and Sp were equal to those observed in the whole cohort. The PPV was higher for MSA (54%) compared to MAA (37%) whereas the NPV was the same for both MSA/MAA (80%). A positive test increases the post-test probability that the patient has myositis of about 30% (LR+=4) for MSA and 15% (LR+=2) for MAA, whereas a negative test does not significantly decrease the probability that the patient has a myositis (LR-=0,8 for MSA and 0,9 for MAA). In 154 patients the test was repeated at least twice, here we found a high agreement between repeated measurements as in only 18% of patients the test retrieved discrepant results. Conclusion: This study may help clinicians to understand the significance and proper use of MSA/MAA in clinical practice. Commercial immunoassays for myositis antibodies show low sensitivity and high specificity, supporting the claim that they should be used for confirmatory rather than screening purposes. Repeating the test does not seem necessary, considering the high agreement in repeated measurements. Combining antibody findings with clinical features will help building up specific diagnostic algorithms for IIM

PS1Group1-003 / #853EXPRESSION OF DP116 IS A PREDISPOSING FACTOR FOR CARDIAC DYSFUNCTION IN DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Tetsushi Yamamoto¹, Awano Hiroyuki¹, Takamitsu Imanishi¹, Yuji Nakamachi¹, Masafumi Matsuo², Kazumoto Iijima³, Jun Saegusa¹

¹Department Of Clinical Laboratory, Kobe University Hospital, --, Kusunoki-cho, Chuo-ku, Kobe, JP;²Department Of Physical Therapy, Faculty Of Rehabilitation, Kobe Gakuin University, kobe, JP;³Department Of Pediatrics, Kobe University Graduate School of Medicine, kobe, JP

Background: BACKGROUND: Duchenne muscular dystrophy (DMD), the most common inherited muscular disease in childhood, is caused by dystrophin deficiency because of mutations in the DMD gene. Cardiomyopathy is the most important non-muscular symptom threatening the life of DMD patients. The correlation between cardiac involvement and dystrophin mutation has been not fully understood since it was analyzed only in the view of mutation position in the DMD gene. In this study, we focused dystrophin isoforms produced by tissue-specific promoters and analyzed relationship between cardiac involvement in DMD patients and disrupted dystrophin isoform. Methods: METHODS: The medical records of DMD patients registered at the Department of Pediatrics of Kobe University Hospital from August 2007 to January 2017 were retrospectively reviewed. All echocardiograms were obtained by 1 examiner (T. Yamamoto), with considerable experience in imaging of patients with DMD, using a commercially available echocardiographic system (Aplio XG; Toshiba Medical Systems, Tochigi, Japan). Total 1109 echocardiographic data were obtained from 181 DMD patients with confirmed mutations in the DMD gene. For Kaplan-Meier analysis, to estimate a cardiac dysfunction-free survival rate, 19 patients were excluded due to existing cardiac dysfunction at the first examination. As a result, the remaining 162 patients were analyzed. Results: RESULTS: A Kaplan-Meier curve revealed that at the age of 14 years, cardiac dysfunction (left ventricular ejection fraction <53%) was observed in nearly half of the DMD patients. To examine the impact of dystrophin isoforms on a cardiac dysfunction, patients were divided by patterns of dystrophin isoform deficiency into 5 groups based on the mutations affecting dystrophin isoforms. The Dp427 group consisted of all 162 patients who had mutations at any position in the DMD gene. The Dp260, Dp140, Dp116, and Dp71 groups consisted of 120, 102, 19, and 11 patients, respectively. The cardiac dysfunction-free survival rates of the Dp260 group was similar to that of the other. Furthermore, the survival rates of the Dp140 and Dp71 groups did not differ significantly from in the others. However, the survival rate was significantly higher in the Dp116 group than in the others (log-rank test, P=0.022). Moreover, patients in the Dp116 group were at lower risk of cardiac dysfunction than the other patients (hazard ratio, 2.89; 95% confidence interval, 1.038–8.045; P=0.042). At age 25 years, the survival rate was 0.6 in the Dp116 group, and 0.15 in the other patients. Left ventricular dilation-free survival rates were estimated in the 5 DMD patient groups and compared with those in other patients. None of these comparisons showed significant differences, including a comparison of patients in the Dp116 group with all other patients (log-rank test, P=0.23). Conclusion: CONCLUSIONS: Cardiac dysfunction was less frequent in mutation of Dp116 coding region than other patients with DMD. These results indicate that Dp116 is a predisposing factor for cardiac dysfunction in DMD.

PS1Group1-004 / #348RIMEPORIDE: RESULTS FROM A PHASE IB STUDY IN PATIENTS WITH DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Teresa Gidaro¹, Laurent Servais¹, Stefano Previtali², Alberto Zambon², Jackie Pitchforth³, Kate Maresh³, Jordi Diaz-Manera⁴, Pierre G. Carlier⁵, Pierre Yves Baudin⁶, Benjamin Marty⁵, Stéphanie Carnesecchi⁷, Christian Laveille⁸, Julian Gray⁹, Florence Porte Thome⁹, Delphine Labolle⁹, Melanie Annousamy¹, Virginie Chê¹, Maria Grazia Natali Sora², Simonetta Gerevini¹⁰, Nuria Vidal⁴, Katie Groves¹¹, Francesco Muntoni³

¹I-motion, Hopital Trousseau, PARIS, FR;²Neurology, San Raffaele Scientific Institute, Milano, IT;³Dubowitz Neuromuscular Unit, UCL Great Ormond Street Institute of Child Health, London, GB;⁴Neuromuscular Disorders Unit, Hospital de la Santa Creu i Sant Pau, Barcelona, ES;⁵Aim & Cea Nmr Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, FR;⁶CRIS, Froyennes, BE;⁷Department Of Pathology And Immunology, Faculty of Medicine, Geneva, CH;⁸Calvagone, Lyon, FR;⁹R&d, EspeRare, Plan les Ouates, CH;¹⁰Department Of Neuroradiology, San Raffaele Scientific Institute, Milano, IT;¹¹Great Ormond Street Hospital For Children, Somers Clinical Research Facility, London, GB

Background: Duchenne muscular dystrophy (DMD) is an orphan disease affecting approximately 1 in 3500 male births worldwide. Children typically lose their ability to walk between 7-13 y and this is followed by progressive respiratory muscle weakness and complications. Cardiac disease is an increasingly important source of morbidity and mortality in these patients. Rimeporide is a first-in-class NHE-1 inhibitor originally developed for congestive heart failure (CHF) that is being repositioned for patients with DMD. Rimeporide demonstrated a beneficial effect in mdx mice and hamster with dilated cardiomyopathy. Its safety, tolerability, and pharmacokinetics were examined in 7 clinical pharmacology studies involving 145 healthy subjects and 21 patients with CHF treated. Rimeporide was well tolerated in healthy male subjects and in patients with CHF as single and multiple doses up to 600 mg. Methods: Rimeporide was tested in a multicentre, European, open-label, Phase 1b study in 6-11 years DMD boys to assess its safety, tolerability and pharmacokinetics and to explore effects on biomarkers (serum and MRI) after a 4-week treatment. 4 dose levels were assessed sequentially through 4 ascending dose cohorts (from 75 to 900 mg daily dose). Dosing in the next cohort being started only after safety was deemed satisfactory at the preceding dose by an independent Safety Monitoring Committee. The trial sites were in Paris, Milan, London and Barcelona. 20 patients were enrolled and completed the study. Results: Over the course of the study, there has been no significant safety ­signal. Safety and tolerability were good in all dose cohorts. Adverse events observed were mild, short-lived, and considered unrelated to study medication. There was one serious adverse event, (loose stools and vomiting requiring overnight hospitalisation in an 8y old patient in cohort 3 receiving 600 mg) on the last day of the dosing period. The SAE was considered to be due to food poisoning and unrelated to Rimeporide. No significant new risks associated with treating young patients with DMD (6 to 11 years old) were identified. The pharmacokinetic profile was in line with the plasma concentrations observed in adults. Rapid absorption, dose related increase in concentration and no accumulation were observed. Serum biomarkers of inflammation and cardiac/skeletal muscle are currently measured. In addition, skeletal muscle MRIs taken at baseline and end of study are currently being analysed centrally. Conclusion: Rimeporide was shown to provide beneficial effects in animal models of DMD & cardiomyopathy and was shown to be well tolerated in healthy adults and now in DMD boys. It has the potential to be a muscle-sparing agent that may alleviate long-term accumulated skeletal and cardiac muscle damage and inflammation. In contrast to many therapeutics under development, rimeporide is potentially applicable to all DMD patients, regardless of the mutation. As it was already shown to be well tolerated in adults and now in DMD boys, it is anticipated that it could be safely combined with other therapies (e.g. corticosteroids, exon skipping, ACE inhibitors..) to achieve synergistic effect. The next milestone is a phase II study to evaluate the efficacy of rimeporide in a larger group of patients.

PS1Group1-005 / #603A LONG TERM PREVENTIVE EFFICACY STUDY WITH RIMEPORIDE, A SODIUM-PROTON EXCHANGER INHIBITOR, IN GRMD DOGS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Inès Barthélémy¹, Jinbo Su², Yves Fromes³, Stéphanie Carnesecchi⁴, Florence Porte Thome⁵, Pierre G. Carlier³, Bijan Ghaleh², Stephane Blot¹

¹U955 - Imrb, Inserm, Ecole Nationale Vétérinaire d’Alfort, UPEC, Maisons-Alfort, FR;²Inserm Umr 955, Institut Mondor de Recherche Biomédicale, Créteil, FR;³Aim & Cea Nmr Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, FR;⁴Department Of Pathology And Immunology, Faculty of Medicine, Geneva, CH;⁵R&d, EspeRare, Plan les Ouates, CH

Background: While the concept around the NHE-1 exchanger inhibition and its cardioprotective effect in models of heart failure is known for over a decade, it is a new concept in Duchenne Muscular Dystrophy (DMD). Cardiac disease is the leading cause of death in DMD and myocardial fibrosis is a key pathology predicting worsening of heart function and cardiac events. Rimeporide, working through inhibition of NHE-1, is cardioprotective in cardiomyopathic hamsters and mdx mice with reduction in cardiac pathology including fibrosis. Rimeporide also showed positive effects on skeletal muscles and diaphragm in mdx mice. Golden Retriever Muscular Dystrophic (GRMD) dogs reproduce the full spectrum of DMD and allow the study of skeletal, respiratory and cardiac outcomes with technologies translatable to patients. This study was designed to collect further knowledge on the co-evolution of cardiac, respiratory and locomotion defects. Methods: This is the largest study ever conducted in GRMD dogs. 24 GRMD dogs received Rimeporide at 20 mg/kg/day or placebo. At 2 months, dogs were stratified using a previously validated method between severe and moderate phenotype. Treatment was blinded, started from the age of 2 months until the age of 10 months. The gait quality was assessed using 3D-accelerometry recording during spontaneous locomotion. Validated clinical scoring analogous to motor scores for DMD patients were performed monthly. Respiratory function was also evaluated monthly using respiratory inductance plethysmography and non-invasive tools including fluoroscopic assessments. Echocardiography, including Tissue Doppler Imaging and speckle tracking techniques (at 2, 4, 6, 9 and 12 months). MRIs (at 2, 6 and 12 months with Gadolinium enhancement for cardiac) were also used for cardiac and skeletal muscles assessments. Serum biomarkers and histopathology analysis are conducted in search of non-invasive biomarkers to be used in patients. Results: A pharmacokinetic study was conducted to select the dose prior to the study initiation. Based on cardiomyopathic hamster and mdx mice studies, therapeutic exposure is above 500 ng/mL. GRMD dogs received 10 mg/kg of Rimeporide as a capsule in the morning and in the evening. Despite a high variability in absorption and elimination, it was possible to confirm that 20 mg/kg/day given as 2 doses of 10 mg/kg/day was maintaining plasma concentration above the therapeutic exposure. 24 GRMD dogs were enrolled and subsequently stratified between moderate and severe forms. At 2-month of age, 6 GRMD dogs were found with decreased stride frequency and a reduced spontaneous speed together with an elevation number of circulating CD4+/CD49dhi T cells and were subsequently assigned as severe forms. 18 additional GRMD dogs were classified as moderate forms. Over the 10-month treatment period, the tolerability of rimeporide was good. As observed in toxicology studies, there was no safety flags. Analyses of skeletal, cardiac, respiratory functions are ongoing and will be discussed in the poster. Conclusion: Results from this translational study in GRMD dogs will contribute to design phase II/III pivotal study by guiding outcome criteria, dose and biomarker selections as well as increasing the understanding of the efficacy profile of Rimeporide in skeletal, respiratory and cardiac muscle and in general supporting DMD disease understanding.

PS1Group1-006 / #458PREDICTORS OF EARLY LEFT VENTRICULAR SYSTOLIC DYSFUNCTION IN DMD PATIENTS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Raphael H.D. Cirino¹, Rosana H. Scola², Renata D. Ducci³, Ana C.C. Wermelinger¹, Claudia S.K. Kay², Paulo J. Lorenzoni², Lineu C. Werneck², Eliane R. Carmes⁴, Claudio L.P. Da Cunha¹

¹Cardiology, Hospital de Clínicas - Universidade Federal do Paraná, Curitiba, BR;²Neurology, Hospital de Clínicas - Universidade Federal do Paraná, Curitiba, BR;³Neurology, Hospital de Clínicas - Universidade Federal do Paraná, Curitiba, BR;⁴Internal Medicine, Hospital de Clínicas - Universidade Federal do Paraná, Curitiba, BR

Background: The life expectancy of Duchenne muscular dystrophy (DMD) patients has improved in the last years, but the management of cardiac complications remains a challenge in DMD therapy. Most DMD patients develop cardiomyopathy, but the symptoms can be masked by severe musculoskeletal weakness. Myocardial strain is an emerging technique that measures myocardial deformation and is able to diagnose left ventricular systolic dysfunction (LVSD) even in the absence of reduced left ventricular ejection fraction (LVEF). Early detection of left ventricular systolic dysfunction (LVSD) is important for therapeutic strategies for DMD patients. We analyzed the myocardial strain by echocardiography as a main tool for the early detection of LVSD and determined the predictors of early LVSD. Methods: Cross-sectional study of forty DMD patients with normal LVEF followed at the Neuromuscular Disorders Service of the Hospital de Clínicas of the Federal University of Parana in Curitiba, Brazil between January 2014 and June 2016. LVEF was measured by 3-dimensional transthoracic echocardiography. Global longitudinal strain (GLS) was used to analyse subtle disturbances in the longitudinal contraction of the myocardium. Patients were determined to have early LVSD [GLS>-18] or normal left ventricular systolic function [GLS≤-18]. Independent samples Student’s t-test was used to compare continuous variables in the studied groups. For qualitative variables, the comparison was made using Fisher’s exact test. We adjusted bivariate logistic regression models for variables with p < 0.05 in the univariate analysis, when possible, including age as covariate. After adjustment, the Wald test was used to assess the significance of the variables included in the model, estimating odds ratios with 95% confidence intervals. P values < 0.05 were considered statistically significant. The study was approved by the Ethics Committee. Results: The study population consisted of 40 DMD male patients aged 2 to 19 years (median: 10.5 years; mean: 10.7 ± 3.9 years). Only 18 patients were still walking. Thirty-one patients used corticosteroids. Twenty (50.0%) patients had early LVSD. The remaining 20 patients had normal LVSF as determined by GLS measurements. Patients who had early LVSD were older and had a longer disease duration and a higher frequency of gait loss, corticosteroid therapy and of mutations in exons 45, 46, 47, 48, 49, 50 and 52. The logistic regression model was adjusted for the analysis of exons 45 (OR 9.6, 95% CI 0.90-102.8, p=0.053) and 50 (OR 36.1, 95% CI 2.15-604.0, p=0.010). It was not possible to adjust the bivariate model for the other variables. Conclusion: Echocardiographic myocardial strain analysis can detect LVSD before the reduction of the LVEF in a large number of DMD patients. The importance of the early detection of LVSD lies in the fact that early initiation of specific treatments could prevent the progression of cardiomyopathy and its complications. The results of this study also suggest that older age, longer disease duration, gait loss, use of corticosteroids and mutations within the “hot spot” region of the DMD gene are predictors of early LVSD.

PS1Group1-007 / #736GENE THERAPY BY CRISPR-CAS9 MEDIATED EXON SKIPPING IN A PRE-CLINICAL MODEL OF DMD, THE GRMD DOG

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Isabel Punzón¹, Inès Barthélémy¹, Frédéric Auradé², Nicolas Blanchard-Gutton¹, France Piétri-Rouxel³, Frédéric Relaix², Stéphane Blot¹

¹Neurobiology, U955 - IMRB, INSERM, Ecole Nationale Vétérinaire d’Alfort, UPEC, Maisons Alfort, FR;²Henri Mondor Hospital School Of Medicine, INSERM-UPEC IMRB U955-E10, Créteil cedex, FR;³Sorbonne Université-UMRS974-Inserm-Institut de Myology, Paris, FR

Background: Duchenne muscular dystrophy (DMD) is a rare degenerative disease without any cure at present. It is an X linked disease due to mutations into the dystrophin gene, that causes the absence of the protein and the progressive degeneration of muscles including heart and diaphragm. Golden Retriever Muscular Dystrophy dog (GRMD) mimics perfectly the DMD and is the accepted pre-clinical large animal model for this disease. The GRMD presents a spontaneous splice site single mutation in the dystrophin gene that leads to the skipping of exon 7, disruption of the reading frame, absence of protein and consequently progressive muscle degeneration, weakness, heart and respiratory failure. A promising approach to cure DMD is gene therapy and specifically exon skipping which efficacy has already been proved restoring partially functional variants of dystrophin. Drugs start to be commercialized to skip exon 51, but a personalised medecine would be preferable. Our group showed that exon skipping strategy using antisense sequences vectorized into adenoassociated vectors (AAV) could rescue the dystrophin absence and significantly improves muscle function in GRMD dogs. However a longterm follow-up showed a decrease in dystrophin expression parallel to a loss of viral genome. To avoid the need of repeated injections of molecules for the exon skipping, with the associated inconvenience for patients and the possible immunoreactions side effects we propose the use of CRISPR tool. This emerging tool for genome editing, appears powerful to perform exon skipping therapy in a permanent way (genome edition of satellite cells) and it has been already successfully proved in mice and human cells. Methods: We started a translational study of genome edition based exon-skipping therapy in GRMD dog, using AAV. 2 pairs of RNA guides were cloned into an AAV-9 vector with tropism for skeletal muscles and heart. A CMV promoter was used for driving the Cas9 and mCherry expression and human and mouse U6 promoters for both gRNAs. A 7 month-old GRMD male dog was intramuscularly injected with an AAV vector containing two RNA guides flanking exons 6 and 9. Results: First, we showed efficacy of CRISPR-exon skipping (6 to 9) in vitro on primary GRMD myoblasts. In vivo, after intramuscular injections, the skipped transcript was detected and associated with dystrophin expression, in biopsies performed 2 months after AAV injection. This is the first proof of principle that genome editing-mediated multi-exon skipping can be performed in a large animal model of DMD, leading to an in-frame transcript and dystrophin expression. Conclusion: Further steps will include systemic delivery of AAVs, to evaluate the levels of dystrophin in targeted muscles and to correlate this to clinical and functional improvements. The genome edition of satellite cells, which would allow a sustained expression of dystrophin, will also be assessed. We also expect to answer crucial preclinical questions of feasibility, bio distribution, efficiency and safety before translation to humans. The GRMD model offers the unique opportunity to study long-term effects (several years) of such a strategy in a dystrophic context and will allow a relevant comparison of the CRISPR based strategy with pre-existing ones.

PS1Group1-008 / #734IN VIVO CELL TRACKING OF CANINE MYOBLASTS  BY SODIUM/IODIDE SYMPORTER GENE EXPRESSION

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Isabel Punzón¹, David Mauduit¹, Inès Barthélémy¹, Nicolas Blanchard-Gutton², Jean-Laurent Thibaud³, Pauline De Fornel³, Bryan Holvoet⁴, Jean-Thomas Vilquin⁵, Maurilio Sampaolesi⁶, Stéphane Blot²

¹Enva, Neurobiology, U955 - IMRB, INSERM, Maisons Alfort, FR;²Enva, Neurobiology, U955-IMRB, INSERM, Maisons Alfort, FR;³58 Rue Auguste Perret,, MICEN Vet,, Créteil, FR;⁴Ku Leuven, Belgium, Translational Cardiomyology Lab, Stem Cell and Embryo Biology, Dept Development & Regeneration,, Leuven, BE;⁵Myology Research Center, Pitié Salpêtrière Hospital,, Sorbonne Université UPMC Univ Paris 06, Inserm UMRS974, CNRS FRE3617, Myology Research Center, Paris, FR;⁶Translational Cardiomyology Lab, Stem Cell and Embryo Biology, Dept Development & Regeneration, Leuven, BE

Background: Cell therapy emerged as a promising approach for the treatment of degenerative muscular diseases but due to disappointing results of clinical trials, efforts need to be done for the identification of the potential therapeutic cell (survival, homing to skeletal muscle, bio distribution, muscle regeneration…). For cell therapy improvement through a better understanding of therapeutic stem cells, we propose a non-invasive cell monitoring by medical imaging that would improve the understanding of the behavior of the cells following transplantation. Methods: We demonstrated the feasibility to track canine NIS⁺ myoblasts by SPECT/CT with specific uptake of ^99mTc-pertechnetate (^99mTcO₄^-) in the skeletal muscle of a large animal. The sodium/iodine symporter (NIS), a natural symporter of iodide in thyroid, salivary glands and stomach was used as a reporter gene. We used a lentiviral vector expressing canine NIS to transduce primary canine myoblasts. Results: NIS did not interfere with myotubes formation, and only cells expressing NIS (myoblasts and myotubes) were able to uptake radioactivity both in vitro and in vivo. We performed whole body scintigraphy imaging after intramuscular injections of different amounts of NIS⁺ and NIS^– expressing myoblasts. SPECT/CT acquisitions at different timepoints until 30 days post cells’ injection were done and biopsies were taken at day 32 for histological analysis. Three millions of NIS expressing myoblasts were detected by scintigraphic imaging only at 48h, 10 millions were detected until one week, and 20 millions were still detected after one month. Histological analysis of injected muscles showed cNIS expression 1 month after cell injection and myoblasts expressing NIS fused with muscle fibers. Conclusion: We demonstrate that this is a non-invasive tool to track cells in vivo, that only functional cells trap radioactivity and that a long-term follow-up is possible being repeatable as many times as necessary. We propose a follow-up study using non-invasive cell tracking by scintigraphy imaging, in combination with functional studies to determine the migratory behavior and therapeutic properties of cells: muscle colonization, dystrophin expression, influences of cells’ environment on their migration and differentiation.

PS1Group1-009 / #928CLINICAL OUTCOME STUDY OF DYSFERLINOPATHY: RELATIONSHIP BETWEEN MUSCLE MRI AND PHYSIOTHERAPY OUTCOME MEASURES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Jordi D. Manera¹, Roberto Fernández-Torrón², Meredith James², Anna Mayhew², Michele Eagle², Robert Muni Lofra², Fiona Smith³, Helen Sutherland², Anne Marie Sawyer⁴, Carolina Tesi Rocha⁵, John W. Day⁵, Anthony Peduto⁶, Kirsti J. Jones⁷, Eva M. Coppenrath⁸, Maggie C. Walter⁹, Pierre G. Carlier¹⁰, Tanya Stojkovic¹¹, Andrew Blamire³, Kate Bushby², Volker Straub¹²

¹Neuromuscular Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, ES;²The John Walton Muscular Dystrophy Research Centre, Newcastle Hospitals Trust, Newcastle University, Newcastle Upon Tyne, GB;³Magnetic Resonance Centre, Institute For Cellular Medicine, Newcastle University, Newcastle Upon Tyne, GB;⁴Lucas Centre For Imaging, Stanford University School of Medicine, Stanford, CA, US;⁵Department Of Neurology And Neurological Sciences, Stanford University School of Medicine, Stanford, CA, US;⁶Department Of Radiology, Westmead Hosptial, Faculty Of Health Sciences, University of Sydney, Sydney, AU;⁷Institute For Neuroscience And Muscle Research, Children’s Hospital At Westmead, University of Sydney, Sydney, AU;⁸Department Of Clinical Radiology, Ludwig-Maximilians-University Munich, Munich, DE;⁹Friedrich-baur Institute, Departement Of Neurology, Ludwigs-Maximilians University of Munich, Munich, DE;¹⁰Aim & Cea Nmr Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, FR;¹¹Ap-hp, G.h. Pitié-salpêtrière 47-83, Boulevard De L’hôpital, Institut de Myologie, Paris, FR;¹²John Walton Muscular Dystrophy Research Centre, Newcastle University, Institute of Genetic Medicine, Newcastle Upon Tyne, GB

Background: Dysferlinopathies are caused by mutations in the DYSF gene. Patients may present with isolated hyperCKemia, limb girdle muscle weakness or predominant weakness of the lower legs. The Jain Foundation is funding The Clinical Outcome Study for Dysferlinopathy, a multi-centre natural history study in a cohort of 203 dysferlinopathy patients. Previous smaller studies have reported an involvement of scapular muscles on muscle MRI but no longitudinal studies have been reported for upper limb involvement in muscle MRI in relation to physiotherapy functional outcome measures. Methods: Here we describe baseline and year 3 upper limb muscle MRI data in a large cohort of dysferlinopathy patients. To examine the longitudinal correlation between muscle MRI semiquantitative scoring and functional outcome measures. 203 patients (11 to 86 years old) were enrolled in the JAIN COS study across 15 centers (Europe, USA, Australia, Japan). Patients underwent physiotherapy, medical and MRI assessments. 74 patients underwent upper limb muscle MRI at the time of enrollment and 61 patients had upper limb muscle MRI at year 3 at the point this analysis was completed. Scans were acquired from different systems and manufacturers at 1.5T and 3T. Muscles were scored on axial T1-weighted sequences with the semiquantitative Mercuri visual scale modified by Fisher. Physiotherapy assessments included muscle strength (manual muscle testing; hand held dynamometry) and functional ability evaluations (Performance of Upper limb, Brooke test). Change between baseline and year 3 muscle MRI was assessed using Wilcoxon’s Signed Rank Tests and statistical significance was set at p=0.05. Results: The subscapularis (80.8%), latissimus dorsi (82.6%), infraspinatus (73.8%) and supraspinatus (72.8%) were the most affected scapular muscles at baseline. The subscapularis muscle was involved in some patients without proximal upper limb symptoms or dysfunction. The biceps brachii (57.1%) and the anterior muscles of the forearm (53.8%) were the most affected muscles from the arm and forearm at baseline. Baseline data identified the tongue (34.2%) and the cervical paraspinal muscles (24.6%) as the most commonly involved cranial and cervical muscles. Cranial and cervical muscles did not show longitudinal change apart for the tongue and cervical paraspinal muscles. Conclusion: Muscle semi-quantitative scoring correlated with functional outcome measures in upper limb in dysferlinopathy patients.

PS1Group1-010 / #10MUSCLE IMAGING AND CLINICAL OUTCOME MEASURES IN OCULOPHARYNGEAL MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

H. M.j.m. Kroon¹, Corinne G. Horlings², J. G. Kalf³, Baziel G. Van Engelen²

¹Rehabilitation, Radboud University Medical Centre, Nijmegen, NL;²Neurology, Radboud University Medical Centre, Nijmegen, NL;³Rehabilitation, Radboud University Medical Centre, Nijmegen, NL

Background: Oculopharyngeal muscular dystrophy (OPMD) is a rare late onset progressive neuromuscular disorder. Currently, there is a profound lack of knowledge on muscle abnormalities in OPMD. Therefore we collected a large data set to present for the first time in OPMD (1) quantitative muscle ultrasound (QMUS) of the head-neck region and legs and its relation to clinical outcome measures and (2) a comparison between QMUS and muscle MRI. Methods: Forty eight OPMD patients (24 Women, mean age 60.5, SD 8.7) including asymptomatic patients, participated. MRI (DIXON, quantitative fat fractions) was used to measure muscle fatty infiltration of the rectus femoris, gastrocnemius, soleus and biceps femoris muscles. QMUS (echo-intensities) was used to measure fatty infiltration of the same leg muscles and of the tongue muscle and masseter muscle. Also, all participants were clinically tested by the Motor Function Measure (MFM) and muscle strength measures (MRC scale and dynamometry) of knee extension, knee flexion, and foot plantar flexion and by measuring the maximum isometric pressure of the tongue (MIP) and maximum bite force (Bite Force Gauge). Correlations were calculated between the echo intensities (EI) and the clinical measurements and between the EI and the mean MRI fat fractions, with accepting r <.30 being a weak, r.30-.70 being a moderate and r >.70 being a strong correlation. Results: Mean EI of all muscles correlated moderately with the MFM (r = -.584; p =.00). EI of rectus and biceps femoris correlated moderately with knee extension and knee flexion strength (r = -.660; p =.00 and r = -.526; p =.00), and moderately with dynamometry of knee extension and flexion (r = -.661; p =.00 and r= -.363; p =.02). EI of the soleus and gastrocnemius did not correlate with foot plantar flexion (r = -.241; p =.11). EI of tongue correlated moderately with the MIP (r = -.633; p =.00), but EI of the masseter did not correlate with the maximum bite force (r = -.271; p =.06). Mean EI and the mean MRI fat fractions are moderately correlated biceps femoris (r =.354; p =.02), rectus femoris (r =.502; p =.00) and gastrocnemius (r =.544; p =.00), except the soleus (r =.193; p =.23). Conclusion: In OPMD patients echo intensity correlates moderately with the measures of maximum motor functioning of the legs and the tongue, but not when using dynamometry or bite force, suggesting that the latter measures are less useful in OPMD. QMUS and MRI of the legs show moderate correlations, suggesting that QMUS of the leg muscles could be used instead of more invasive and expensive MRI.

PS1Group1-011 / #444DIGENIC SQSTM1-TIA1 MYOPATHY: CLINICAL AND PATHOLOGICAL FEATURES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Zhiyv Niu¹, Carly S. Pontifex², Sarah Berini¹, Leslie E. Hamilton², Elie Naddaf¹, Eric Wieben¹, Ross A. Aleff¹, Kristina Martens², Angela Gruber³, Andrew G. Engel¹, Gerald Pfeffer², Margherita Milone⁴

¹Mayo Clinic, Rochester, MN, US;²Clinical Neurosciences, University of Calgary, Calgary, AB, CA;³PreventionGenetics, Marshfield, WI, US;⁴Neurology, Mayo Clinic, Rochester, MN, US

Background: T-cell intracellular antigen-I (TIA1, chr.2) is a largely expressed RNA-binding protein required for the cytoplasmic stress granules formation, which is a crucial step in preventing misfolded protein accumulation. To date, a single TIA1 mutation (p.Glu384Lys) is known to cause a late-onset myopathy with rimmed vacuoles. TIA1 mutations were recently identified in amyotrophic lateral sclerosis (ALS) / frontotemporal dementia (FTD). Sequestosome-1 (SQSTM1, chr.5) is a scaffolding protein participating in apoptosis, cell survival, autophagy, and regulation of ubiquitinated protein turnover. Mutations in SQSTM1 can cause a multisystem proteinopathy manifesting as Paget disease of bone (PDB), ALS, FTD and myopathy with rimmed vacuoles but have incomplete penetrance. Methods: Review of clinical, serological, electrophysiological, muscle morphological, cardiac and radiological findings of three unrelated probands with late-onset distal myopathy and their affected and unaffected family members, including the affected fraternal twin of a proband. Next Generation Sequencing panel, whole exome sequencing, and targeted Sanger sequencing analyses of family members were performed to investigate the molecular genetic etiology of the myopathy. Results: Genetic analyses detected two variants in genes located on different chromosomes responsible for the myopathy in the three unrelated probands: a heterozygous pathogenic mutation in SQSTM1 (c.1175C>T, p.Pro392Leu) and a heterozygous variant in TIA1 (c.1070A>G, p.Asn357Ser). The affected fraternal twin of a proband carries both variants; the unaffected family members have one or no variants. Two probands have a distal myopathy with rimmed vacuoles that presented with weakness of the index extensor; the other proband has a distal myopathy with myofibrillar pathology accompanied by hypercapnic respiratory insufficiency. Some of the affected individuals in a family have cognitive impairment. Conclusion: 1) The affected individuals of three unrelated families have a myopathy associated with both variants, one in SQSTM1 and one in TIA1 (genes located on different chromosomes), suggesting that the myopathy is digenic. 2) The combined SQSTM1 and TIA1 variants can cause myofibrillar myopathy, and therefore, analysis of both genes should be considered in the molecular investigation of myopathy with rimmed vacuoles as well as in the genetic characterization of myofibrillar myopathy. 3) Respiratory insufficiency can occur in SQSTM1-TIA1 myopathy and, therefore, patient’s respiratory status should be closely monitored. 4) The cognitive impairment observed in a family is in keeping with the known deleterious effects of TIA1 and SQSTM1 mutations on central nervous system, previously reported in the form of FTD.

PS1Group1-012 / #26PATHOLOGICAL AND GENETIC STUDIES IN PATIENTS WITH MENDELIAN DISORDERS OF MTDNA MAINTENANCE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Diana Lehmann¹, Amy E. Vincent², Hannah Rosa², Mariana Rocha², Stephan Zierz³, Robert W Taylor², Douglass M. Turnbull²

¹Department Of Neurology, University of Ulm, Ulm, DE;²Institute Of Neuroscience, Newcastle University Wellcome Trust Centre for Mitochondrial Research, Newcastle upon Tyne, GB;³Department Of Neurology, University of Halle/S., Halle/S., DE

Background: The underlying genetic defect in patients with mitochondrial PEO is either a primary mutation of the mitochondrial genome (single, large-scale mtDNA deletion or mtDNA point mutation) or recessively and dominantly-inherited mutations in nuclear genes involved in mtDNA maintenance leading to clonally-expanded multiple mtDNA deletions in muscle. The nuclear disease genes are largely implicated in the replication and stability of mtDNA, and as such a pathogenic mutation leads to secondary instability of the mitochondrial genome. Causal mtDNA deletions can be found in a heteroplasmic (mixture of mutated and wild type mtDNA) state. However, each tissue/cell has its own genetic defect and biochemical threshold of mutated mtDNA load which needs to be exceeded before focal respiratory chain deficiency becomes evident. Methods: To investigate this, muscle biopsies of 16 patients with genetically- and clinically-characterized mitochondrial disease of nuclear origin (9 POLG, 4 TWNK, 2 RRM2B and 1 SLC25A4 (ANT1)) and 4 healthy controls were analysed using quadruple OXPHOS immunohistochemistry, quantifying the biochemical phenotype in individual muscle fibres of patient muscle biopsies. This technique is based on quadruple immunofluorescence to detect structural components of complexes I (NDUFB8) and IV (COXI), as well as porin (a marker of mitochondrial mass) and laminin (a cell membrane marker to define the boundaries of muscle fibres). Further studies on 6/17 patients (2 POLG, 2 RRM2B, 1 TWNK, 1 SLC25A4 (ANT1)) included the correlation of the biochemical deficiency with the mtDNA abnormality in individual cells, following laser microcapture and determination of the size and level of clonally-expanded mtDNA deletion within fibres by real-time PCR, long-range PCR and sequencing of breakpoints. Results: The data from quadruple immunocytochemical studies show that the muscle biochemical phenotype is different in patients with multiple mtDNA deletions compared to other mtDNA mutations, but showed no difference between genotypes. Real-time PCR showed, that the level of deletion is increasing with the biochemical defect. In all patients, the levels of deletion of ND4/D Loop and ND4/ND1 are significantly increasing with the MRC profile. However, in all groups of fibres there seem to be very low levels of ND1 deletions. Conclusion: It has already been shown, that patients harbouring multiple deletions have a distinct MRC- (muscle respiratory chain) profile. Three different groups of fibres were found in these patients: cells without deficiency, cells with isolated complex I deficiency and cells with combined complex I and complex IV deficiency. The correlation of biochemical deficiency with level of deletion is arguing against any point mutations as cause of the deficiency.

PS1Group1-013 / #451EPILEPSY CHARACTERIZATION IN LAMA2-RELATED CONGENITAL MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Daniel Natera De Benito¹, Debora Itzep², Jordi Muchart², Alia Ramirez², Delia Yubero², Laura Carrera², Javier Aparicio², Cristina Jou², Cecilia Jimenez Mallebrera², Jaume Colomer², Carlos Ortez², Andres Nascimento², Victoria San Antonio Arce²

¹Neuromuscular Disorders Unit, Hospital Sant Joan de Déu, Barcelona, ES;²Hospital Sant Joan de Déu, Barcelona, ES

Background: LAMA2-related congenital muscular dystrophy (CMD), is an autosomal recessive neuromuscular disorder resulting in deficiency of the laminin a2 chain, a component of the skeletal muscle extracellular matrix laminin-2. Laminin-2 is expressed in basement membranes of striated muscle, but also in the neuromuscular synapses, schwann cells and in brain where it is thought to have a role in neuronal migration. Although it is a muscular disease, it may be associated with peripheral neuropathy and a diversity of cerebral manifestations. The risk of epileting seizures is described in the literature up to 20% of the cases, even without cerebral structural anomalies on MRI. Although both focal and generalized seizures have been reported, the epilepsy phenotypic spectrum has not been defined. In this study we describe the epilepsy phenotype in a cohort of patients with LAMA2-related CMD who have experienced seizures in order to clarify the spectrum of phenotypes that may occur. Electroclinico-radiologic presentation, response to treatment, and long-term outcome are described. Methods: All patients with genetically and/or pathologically confirmed diagnosis of LAMA2-related CMD followed-up in our hospital were included. Medical records of patients with demographic information, clinical data, EEG records, and MRI studies were compiled. Seizures and epilepsy were described and classified according to the ILAE classifications. Results: Epilepsy was observed in eight of twenty patients with LAMA2-related CMD. A partial merosin deficiency was detected in five patients and a complete merosin deficiency in three. The mean age at the time of the study was 19.5 years (range 10-32 years). Mean age at seizure onset was 8 years (range 2-20 years). The most common presenting seizure type was focal onset seizure with or without impaired awareness in 5 of 8 subjects. Visual aura was described in four patients. Vomiting was also frequently reported (4/8).Three subjects had motor seizures with an unknown onset. Two subjects also had bilateral tonic-clonic seizures. One case had atypical absences and drop attacks. Long-term seizure control was assessed based on the Brodie classification: six patients (75%) had ongoing refractory seizures (D), and two (25%) had fluctuating course (C: periods of at least 12 months seizure-free, interspersed with relapses). Interictal EEGs showed focal or multifocal epileptiform abnormalities in seven of eight cases. Focal occipital abnormalities were the most commonly observed. Background activity was normal in six patients, and generalized background slowing was reported in two cases An increased signal intensity of subcortical and periventricular white matter on T2-weighted MRI was reported in all the patients. Four patients (50%) had suspected focal cortical dysplasia. Conclusion: The epilepsy in LAMA2-related CMD typically presents with childhood-onset focal seizures that are not usually prolonged and have prominent visual and autonomic features. EEG show focal interictal abnormalities that predominate in the posterior quadrants. MRI brain demonstrates a constellation of structural abnormalities, including focal cortical dysplasia, in addition to the well-known increased signal intensity of white matter on T2-weighted MRI.

PS1Group1-014 / #786A PHASE 1B/2 STUDY OF THE ANTI-MYOSTATIN ADNECTIN RG6206 (BMS-986089) IN AMBULATORY BOYS WITH DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Kathryn R. Wagner¹, Brenda L. Wong², Barry Byrne³, Lee Sweeney³, Leslie Jacobsen⁴, Giridhar Tirucherai⁴, Michael Rabbia⁵, Jeppe Buchbjerg⁶, Dukart Juergen⁶, Michelle Krishnan⁶, Clifford Bechtold⁴

The Johns Hopkins School of Medicine, Baltimore, MD, US;²Neurology, Cincinnati Children’s Hospital Medical Center, Cincinatti, OH, US;³University of Florida, Gainesville, FL, US;⁴Bristol-Myers Squibb, Princeton, NJ, US;⁵Roche Translational and Clinical Research Center, New York, NY, US;⁶F. Hoffmann-La Roche Ltd, Basel, CH

Background: Pharmacologic inhibition of myostatin, a negative regulator of muscle growth, has been shown to increase skeletal muscle mass in several species, including humans. RG6206 is a potent, novel anti-myostatin adnectin previously shown to inhibit myostatin activity in healthy adults. This Phase 1b/2 study (NCT02515669) assessed the safety, tolerability, pharmacokinetics and pharmacodynamics of the novel anti-myostatin adnectin RG6206 (BMS-986089) in ambulatory boys with Duchenne muscular dystrophy (DMD). Methods: Forty-three ambulatory boys with DMD aged 5–10 years were randomized to receive weekly subcutaneous doses of RG6206 (4–50 mg) or placebo. The primary endpoint was safety over 24 weeks. Secondary endpoints included pharmacokinetics of RG6206, frequency of anti-drug antibodies and pharmacodynamic effect on serum myostatin levels. Exploratory outcome measures included 4-stair climb velocity (4SC), 6-minute walk test (6MWT) and North Star Ambulatory Assessment (NSAA) score. Muscle volume and lean body mass were assessed by dual-energy X-ray absorptiometry (DXA) or magnetic resonance imaging (MRI). Results: No clinically significant changes in laboratory values, vital signs or echocardiogram parameters were observed over 24 weeks. The most common adverse events considered to be related to study drug were cutaneous injection site reactions (RG6206 n=10, 31.3%; placebo n=1, 9.1%), which were mild (except one event of moderate injection site discomfort). One patient tested positive for anti-drug antibodies; however, this patient had a positive titer at baseline. RG6206 serum concentrations increased with dose and were accompanied by dose-dependent reduction in free myostatin, with a ≥ 95% reduction from baseline with the highest dose. The study was not powered to demonstrate effects on exploratory functional endpoints and, as such, no efficacy on 4SC, 6-MWT and NSAA score was observed. However, DXA imaging data showed an increase in lean body mass in boys receiving RG6206 compared with placebo. In addition, MRI imaging of the right thigh showed positive effects on muscle composition due to RG6206, with an increase in contractile, and decrease in non-contractile, tissue. Conclusion: RG6206 was well tolerated by ambulatory boys with DMD, with no clinically significant safety concerns. Robust anti-myostatin target engagement was demonstrated, and DXA and MRI imaging outcomes suggest a positive effect of RG6206 on muscle over the 24-week study. A 48-week open-label phase of this study is ongoing and a Phase 2/3 study is underway to further evaluate RG6206 in ambulatory boys with DMD (NCT03039686). Acknowledgements Study sponsored by F. Hoffmann-La Roche.

PS1Group1-015 / #350IN VITRO FUNCTIONAL CHARACTERIZATION OF FKRP PATIENT MISSENSE MUTATIONS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Sara F. Dias Henriques, Evelyne Gicquel, Justine Marsolier, Isabelle Richard

INTEGRARE, Généthon, Inserm, Univ Evry, Université Paris-Saclay, Evry, FR

Background: Muscular dystrophies are monogenic diseases affecting the skeletal muscle, characterized by a progressive loss of the muscle mass, can lead to premature death by heart or respiratory complications and are currently without treatment. One group of muscle dystrophies termed “dystroglycanopathies” encompasses different genetic pathologies that lead to a change in the glycosylation status of the protein alpha-dystroglycan (alpha-DG). This protein is a crucial component of the dystrophin-associated glycoprotein complex (DGC) at the skeletal muscle whereby, through a complex and specific glycosylation, the plasma membrane is anchored to the extracellular-matrix. Loss of this glycosylation weakens this link and leads to the death of muscle fibers. Many proteins cooperate in the assembly of the final glycosylation moiety such as the Fukutin-Related Protein (FKRP). Mutations in FKRP lead to different pathologies, from the severe Congenital Muscular Dystrophy type 1C (MDC1C) to the mild Limb-Girdle Muscular Dystrophy type 2I (LGMD2I) and one of the most prevalent of the LGMD group. Most patient-mutations are missense mutations, some of which leading to a misfolded protein that is retained in the endoplasmic reticulum (ER) and prematurely degraded before reaching the functionality compartment, the Golgi (Esapa et al., 2002 and 2005; Torelli et al., 2005; Keramaris-Vrantsis et al., 2007). We have shown that some LGMD-associated misfolded proteins still retain partial function when rescued to the correct compartment (Soheili et al., 2011). It is therefore crucial to assess the functionality of FKRP mutant proteins in line with potential corrective treatments. Methods: Through transgene overexpression in a FKRP knockout (KO) cell line, we have characterized different patterns of cellular localization of the mutant proteins, some of which never described before. Results: Combination of these localization results with functional assays lead to the identification of some mutants that still bear function when properly addressed to the Golgi. Interestingly we have also identified mutants that, although correctly localized in the Golgi, where nonetheless severely functionally impaired, revealing that accurate cellular localization is not directly linked with function. Structural analysis is currently being pursued in understanding the function impairment of these mutants. Conclusion: Our results clearly show that cellular localization studies are not enough to fully understand the consequences of the mutations and a complementary functional assessment of the mutated proteins is required when curative treatments are envisioned.

PS1Group1-016 / #528IDENTIFICATION OF MUTATIONS IN A COHORT OF UNCLASSIFIED INHERITED MUSCLE DISORDERS BY TARGETED NEXT GENERATION SEQUENCING

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Kiran Polavarapu¹, Aditi Joshi², Veeramani Preethish-Kumar¹, Aradhna Mathur², Sushmita Nayak², Sakshi Ambawat², Saraswati Nashi³, Seena Vengalil³, Rashmi Santhosh⁴, Gayathri Narayanappa⁴, Mohammed Faruq², Atchayaram Nalini⁵

¹Clinical Neurosciences, Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, IN;²Institute of Genomics and Integrative Biology, New Delhi, IN;³Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, IN;⁴Neuropathology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, IN;⁵Neurology, National Institute of Mental Health and Neurosciences, IN

Background: Inherited myopathies and muscular dystrophies are a genetically heterogenous group of neuromuscular disorders which often present with overlapping clinical and pathological phenotypes. Although muscle histochemistry, immunostaining, western-blot and electron microscopy techniques offer important clues, these are often found insufficient to provide a conclusive diagnosis. With rapid evolution of gene discovery, accurate molecular diagnosis is essential for these disorders to provide appropriate genetic counselling, prognostication and identification of disease burden essential for future therapeutic research. Targeted Next generation sequencing (NGS) with gene panels are emerging as quick low-cost methods to diagnose mendelian disorders.

Methods: Randomly selected patients with clinical features suggestive of Limb girdle muscular dystrophies (LGMD), distal myopathies (DM) and congenital myopathies (CM) evaluated over last 10 years in our Neuromuscular clinic were taken up for genetic analysis by Targeted NGS with a gene panel constituting 53 known muscular dystrophy and myopathy genes. DNA extracted from blood was utilized for library preparation as per Agilent SureselectQXT protocol followed by sequencing on HIseq Illumina platform.

Results: We performed Target NGS in 45 patients with mean age of 21±11.7 (3-49 years) and male/female ratio of 3:2. Broad clinical phenotypes included LGMD: 31 (68.9%), CM: 9 (20%), DM: 5 (11.1%). Majority of cases were sporadic: 33 (73.3%), while family history was present in 12 (26.7%): Autosomal dominant inheritance in 7, recessive history in 3 and suspected X-linked inheritance in 2 families. Serum Creatine kinase was elevated in 82.2% (>5 times: 22, <5 times: 15). Muscle biopsy reports available in 42 patients showed muscular dystrophy in 25 (60.9%). Myopathic features were reported in 17 patients showing varying degree of cytoplasmic inclusions in 9 cases and rimmed vacuoles in 4. Putative disease-causing variants in 17 genes were identified in 31 patients (68.8%) and diagnosis was possible in 21 (46.66%) where clinical suspicion was supportive, and variants were either reported pathogenic or novel rare variants (MAF=0) recognized as damaging/probably damaging by in-silico predictions (Table 1). In another 10 cases, variants were identified with uncertain significance/not exactly correlating with phenotype and need to be further characterized. Most common genes affected were CAPN3 (Calpain-LGMD2A) in 5 patients followed by DYSF (Dysferlin-LGMD2B), EMD (Emerin-EDMD) in 4 cases each, RYR1 (Ryanodine receptor1-CM) in 3 and GMPPB (LGMD 2T), LMNA (LGMD 1B/EDMD) in 2 each.

Conclusion: Targeted gene panel NGS offers a quick cost-effective strategy with good diagnostic yield in inherited muscle disorders, when complimented with proper clinical phenotyping.

PS1Group1-017 / #849L-CITRULLINE AND METFORMIN DELAY MUSCLE DEGENERATION IN DUCHENNE MUSCULAR DYSTROPHY: RESULTS FROM A ANDOMISED CLINICAL TRIAL

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Patricia Hafner¹, Ulrike Bonati¹, Andrea Klein², Daniela Rubino¹, Vanya Gocheva¹, Simone Schmidt¹, Vincent Laugel³, Andrea Capone⁴, Monika Gloor⁵, Oliver Bieri⁵, Thomas Zumbrunn⁶, Nuri Gueven⁷, Dirk Fischer⁸

¹Division Of Paediatric Neurology, University Children’s Hospital Basel, Basel, CH;²Division Of Paediatric Neurology, University of Berne Hospital, Berne, CH;³Strasbourg University Hospital, Strasbourg, FR;⁴Division Of Paediatric Neurology, Children’s Hospital Aarau, Aarau, CH;⁵Department Of Radiology, University of Basel Hospital, Basel, CH;⁶Department Of Clinical Research, University of Basel Hospital, Basel, CH;⁷Pharmacy, School Of Medicine, University of Tasmania, Hobart, AU;⁸Division Of Neurology, Kantonsspital Bruderhlz, Bruderholz, CH

Background: Sufficient therapeutic efficacy in Duchenne muscular dystrophy (DMD) has not been achieved yet and current therapeutic management still remains supportive. Recent evidence suggests that the loss of dystrophin in DMD not only disturbs cytoskeletal integrity but also cell metabolism resulting in reduced intracellular nitric monoxide (NO) levels. This phase IIa clinical trial assessed the efficacy and safety of the NO enhancing components L-citrulline and metformin to protect against muscle degeneration in ambulant patients with DMD. Methods: 49 ambulant DMD patients aged between 6.5 and 10 years were screened and 47 randomly allocated in a 1:1 ratio to receive daily treatment with oral L-citrulline (2.5g three times a day) and metformin (250mg three times a day) or placebo for 26 weeks. Co-medication with glucocorticoids was allowed if started 6 months prior to randomisation. Primary endpoint was the change of motor function measure (MFM) D1 subscore from baseline to week 26 in the modified intention to treat (mITT) patient set. Secondary endpoints included the total MFM score and its subscores; 6 min walking distance; timed function tests, quantitative muscle testing, quantitative muscle MRI assessments and biomarker laboratory analysis. Two subgroups were defined by a 6 min walking distance (6MWD) of ≥350m (stable) and < 350m (unstable) at baseline. Results: 45 of the 47 randomised patients (mean age 8.20 [1.07] years; 45 [100%] boys) completed the study. At week 26, L-citrulline and metformin treatment improved the MFM D1 decrease compared to placebo non-significantly (mean difference 5.54% [95% CI -1.00 to 12.09]; P =.095). Significant differences in favor of the L-citrulline and metformin treatment were observed in the stable subgroup with a baseline 6 MWD of ≥ 350m (mean MFM D1 difference of 6.81% [95% CI 1.00 to 12.26]; P =.024) and on both quantitative MRI sequences to assess muscle degeneration (mean fat fraction difference -1.79 [95% CI -3.26 to – 0.32]; P =.018; mean T2 relaxation time difference -1.33 [95% CI -2.40 to – 0.26]; P = 0.016). The treatment with L-citrulline and metformin was well tolerated, with stomach-ache, a known side effect of metformin, as the most frequent adverse event. Conclusion: The non-significant difference of the D1 in the mITT in favor of L-citrullin and metformin is clinically meaningful, but the study is underpowered.

PS1Group1-018 / #814MUTATION ANALYSIS IN MLPA NEGATIVE DUCHENNE MUSCULAR DYSTROPHY: NGS AS A DIAGNOSTIC TOOL PRIOR TO MUSCLE BIOPSY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Kiran Polavarapu¹, M K. Saroja², Veeramani Preethish-Kumar¹, Deepah Sekar³, Saraswati Nashi⁴, Seena Vengalil⁴, Priya T. Thomas⁵, Sudha N. Rao², Atchayaram Nalini⁶

¹Clinical Neurosciences, Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, IN;²R&d Division, Genotypic Technology, Bangalore, IN;³NIMHANS, Bengaluru, Bengaluru, IN;⁴Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, IN;⁵Department Of Psychiatric Social Work, National Institute of Mental Health and Neuro Sciences, Bangalore, IN;⁶Department Of Neurology, National Institute of Mental Health and Neuro Sciences, Bangalore, IN

Background: Duchenne muscular dystrophy (DMD) is the most severe and common form of childhood muscular dystrophies resulting from mutations in Dystrophin gene (Xp21), affecting 1 in 3500 boys worldwide. While 75% patients have deletions/duplications of one or more exons, smaller mutations - point mutations, insertion/deletions (INDELs) etc., occur in 20-25% who require direct sequencing of entire gene or invasive muscle biopsy for diagnostic confirmation. Next generation sequencing (NGS) offers a cheaper and higher throughput alternative to traditional Sanger sequencing and can be developed as a single diagnostic platform to identify both copy number variations (CNVs) and small mutations in DMD patients. Methods: Clinically suspected and/or biopsy confirmed DMD children in whom MLPA (Multiplex ligation-dependent probe amplification) did not identify deletions/duplications of exons were recruited from our Neuromuscular clinic. Custom probe design for DMD gene was created using Agilent’s SureDesign^TM tool with a total capture size of 2.077Mbp to cover entire gene (exons, introns and promoter regions) at least twice. After obtaining informed consent/assent, DNA extracted from blood was used to prepare libraries and sequenced on NextSeq^TM(Illumina). Results: Mutational analysis was performed in 64 MLPA negative DMD children with mean age of 7.87±2.3 (range:3-13 years). Majority were sporadic cases and family history (X-linked recessive) is present in only six cases (9.37%). Biopsy was performed in 51 boys (79.7%) and showed loss of Dystrophin on immunohistochemistry. NGS identified hemizygous mutations of DMD gene in 58/64 children (90.6%). Nonsense mutations were most common at 54.7% (35/64) followed by frameshift mutations due to small INDELs 21.9% (14/64). Small INDELs of up to 10 bases were identified accurately. Variants affecting splicing occurred in 8/63 (12.5%) out of which six involved invariant GT and AG dinucleotides at the 5’ end (splice donor) and 3’ end (splice acceptor) of introns. Missense mutation was identified in only one patient. Except for one splice mutation where variation occurred nine bases upstream of exon 12, all other variants were classified as pathogenic (55) or likely pathogenic (2) as per ACMG guidelines. In total there were 57 unique variants among which 60% (34) were novel and only one mutation (p.Arg539*) recurred in two unrelated patients. Unlike larger CNVs, which occur predominantly in exons 45–55 and 2–10 for deletions and duplications respectively, small mutations lacked any hot spot regions and more uniformly spread across coding region with exons 30 and 44 having most number of mutations (4 each). In thirteen patients who did not undergo biopsy and clinical suspicion was high, we were able to accurately identify pathogenic mutations. Mutations were not identified in only six cases (9.5%), where possibility of deep intronic variants/complex rearrangements should be considered. Conclusion: In this study we describe spectrum of smaller mutations in a large cohort of DMD children from India. Accurate diagnosis of these mutations is important to identify potential cases who can benefit from mutation specific therapies like nonsense read-through and NGS offers a valuable diagnostic screening tool before contemplating invasive muscle biopsy in clinically suspected DMD patients. Acknowledgement: This study is funded by DST-SERB (Govt. of India) project: EMR/2014/000943

PS1Group1-019 / #756EZUTROMID SIGNIFICANTLY REDUCES MUSCLE DAMAGE IN DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Francesco Muntoni¹, Gary Layton², Indranil Bhattacharya³, Krista Vandenborne⁴, Crystal Faelan⁵, Anne Heatherington³, David Roblin⁶, Ruth Osahon⁶, Jon Tinsley⁷, Kay Davies⁸

¹Dubowitz Neuromuscular Unit, UCL Great Ormond Street Institute of Child Health, London, GB;²Summit Therapeutics Inc., Abingdon, AL, GB;³Summit Therapeutics Inc., Cambridge, MA, US;⁴University of Florida, Gainsville, FL, US;⁵Flagship Biosciences, Westminster, CO, US;⁶Summit Therapeutics Inc., Abingdon, GB;⁷Summit Therapeutics Plc, Abingdon, GB;⁸university of oxford, oxford, GB

Background: To share interim 24-week safety and efficacy results from PhaseOut DMD evaluating ezutromid, a potential first-in-class utrophin modulator for the treatment of all patients with Duchenne muscular dystrophy (DMD). Utrophin is a naturally occurring protein that may act as a functional replacement for dystrophin. Increasing the production of utrophin in mature muscle fibres protects and improves outcome in preclinical models, and could modify the course of DMD. Methods: PhaseOut DMD is a Phase 2 open-label study of ezutromid administered to 40 ambulatory patients with DMD. Primary endpoints (48 week) are magnetic resonance spectroscopy (MRS) assessments. Key secondary endpoints are evidence of target engagement and quantification of muscle damage on muscle biopsies; collected at baseline (n=40) and week 24 (n=25) or 48 (n=15). Safety, pharmacokinetics, and functional measures are monitored throughout. Safety monitoring included collection of treatment emergent adverse events (TEAE), electrocardiogram (ECG), echocardiogram (ECHO), and laboratory parameters. An interim 24-week analysis was planned to assess efficacy and safety compared to baseline, with a focus on changes in the degree of muscle pathology as monitored by muscle biopsy. Results: A statistically significant reduction in %fibres expressing developmental myosin (MHCd) was observed (from 11.37% to 8.76%, least mean square difference (LSMD) -2.62% CI, -4.33, -0.90); a relative reduction of 23%. Mean utrophin intensity increased (relative +7%) (0.370 to 0.396, LSMD 0.026 95% CI, -0.005, 0.058). MRS indicated a statistically significant decrease in water relaxation time (T2) in the soleus muscle: the average reduction was -0.86 milliseconds (95% confidence intervals -1.44, -0.28), which was from 31.85 milliseconds at baseline to 30.99 milliseconds at 24 weeks, (n=38). Further, an increase in mean fat fraction (vastus lateralis: from 14.7% to 18.5%, n=37) was noted. No patient lost ambulation and there were no meaningful changes in functional performance (eg 6MWD: 404m at baseline, 395m at 24 weeks, n=39). All patients achieved ezutromid plasma levels sufficient to modulate utrophin. Up to Week 24, none of the subjects had any clinically significant TEAE, and no subject withdrew due to safety issues. Only one subject experienced an SAE, which resolved within a day with no dosage day missed, whilst the subject remained in the study. In addition, there was no relevant prolongation of the corrected QT interval on the ECG, or deterioration of left ventricular ejection fraction or fractional shortening. There were no clinically significant laboratory abnormalities related to ezutromid use. Ezutromid continues to be safe and well tolerated. Conclusion: Decreased MHCd, a marker of regeneration, indicates reduction in muscle damage. Utrophin levels were increased which, with decreasing MHCd, provides evidence of target engagement. MRS T2 results in this age group are consistent with a reduction in muscle inflammation and/or damage. Ezutromid has continued to be safe and well-tolerated after prolonged dosing across a wide exposure range. These interim results support utrophin modulation as a potential treatment for DMD patients irrespective of their mutation.

PS1Group1-020 / #698NUMBER NEEDED TO TREAT IN SPINAL MUSCULAR ATROPHY TYPE 1 WITH AVXS-101 RELATIVE TO NUSINERSEN

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Omar Dabbous¹, Martin Cloutier², Annie Guerin², Irina Pivneva², Eric Q. Wu², Douglas M. Sproule³

¹AveXis, Inc., Bannockburn, AL, US;²Analysis Group, Inc., Boston, MA, US;³AveXis, Inc., Bannockburn, IL, US

Background: To assess the number needed to treat (NNT) to prevent death and use of permanent assisted ventilation and to improve motor function with AVXS-101 compared to nusinersen in patients with spinal muscular atrophy type 1 (SMA1). Methods: Patients diagnosed with SMA1 were treated in clinical trials with AVXS-101 (NCT02122952; study cohort 2; N=12) or nusinersen (NCT02193074; N=80). Trial duration was up to 24 months for AVXS-101 (median = 24.1 months) and up to 13 months for nusinersen (median = 9.2 months). NNT with AVXS-101 compared to nusinersen was assessed for survival and event-free survival (absence of death and use of permanent assisted ventilation) at last visit, and for motor function (increase of ≥4 points in Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders [CHOP-INTEND] score from baseline) at last visit and at a median of 9 months. For the nusinersen trial, CHOP-INTEND score was measured for patients with ≥6 months of follow-up (N=73). The NNT to prevent one death, one event (death or use of permanent assisted ventilation), or for one patient to improve motor function relative to nusinersen was calculated as the reciprocal of the difference between AVXS-101 and nusinersen in event rates or motor function achievement rates. Results: Patient mean age at first dose was 3.4 (0.9-7.9) and 5.3 (1.7-7.9) months in the AVXS-101 and nusinersen trials. NNT analyses showed that treating 6.2 patients with AVXS-101 instead of nusinersen would prevent 1 more death over the course of the study interval; treating 2.6 patients with AVXS-101 versus nusinersen would prevent 1 more event; and treating 3.5 patients with AVXS-101 versus nusinersen would allow 1 more patient to improve motor function (at last visit and at a median of 9 months). Conclusion: Efficacy in preventing death and use of permanent assisted ventilation and in improving motor function is much higher with AVXS-101 versus nusinersen.

PS1Group1-021 / #821A NOVEL NEXT-GENERATION THERAPY FOR POMPE DISEASE WITH IMPROVED EFFICACY IN MICE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Su Xu, Yi Lun, Rebecca Soska, Anju Nair, Michelle Frascella, Anadina Garcia, Abdul S. Ponery, Jessie Feng, Cecilia Della Valle, Russell Gotschall, Hung Do, Kenneth J. Valenzano, Richie Khanna

Amicus Therapeutics, Cranbury, US

Background: Pompe disease is a lysosomal storage disorder that results from deficiency in acid a-glucosidase (GAA) activity, and is characterized by progressive accumulation of lysosomal glycogen in cardiac and skeletal muscles. Currently, the only approved treatment is enzyme replacement therapy using biweekly infusions of a recombinant human GAA (rhGAA), alglucosidase alfa. Although alglucosidase alfa provides some clinical benefits, the infused enzyme shows insufficient uptake into key disease-relevant skeletal muscles, mainly due to sub-optimal levels of mannose-6-phosphate (M6P), a carbohydrate that binds cation-independent M6P receptors at the cell surface, resulting in enzyme ­internalization and lysosomal targeting. Methods: We have developed a proprietary, novel rhGAA, ATB200, that has optimized M6P content due to its combination of a specialized cell line and an optimized manufacturing/purification process. Moreover, we are developing ATB200 to be co-administered with a small molecule pharmacological chaperone, AT2221 (miglustat, N-butyl-deoxynojorimycin), as a next-generation therapy for Pompe disease. Results: ATB200 use led to substantially greater lysosomal targeting compared to alglucosidase alfa following intravenous injection to Gaa knock-out (KO) mice. Our data indicate that AT2221 stabilizes ATB200 in blood ex vivo and improves its pharmacokinetic properties in vivo. In Gaa KO mice, co-administration of ATB200 with AT2221 (ATB200/AT2221) showed significantly greater glycogen reduction in key disease-relevant muscles compared to alglucosidase alfa. Repeat administrations of ATB200/AT2221 also substantially reduced lysosomal proliferation, reversed autophagic buildup, and increased muscle fiber size. The effects seen at the biochemical and cellular levels ultimately translated into improved muscle function in Gaa KO mice compared to the standard of care. Conclusion: Collectively, these data demonstrate the superiority of ATB200/AT2221 over the current approved therapy in these preclinical studies, warranting further investigation as a treatment of Pompe disease.

PS1Group1-022 / #360THE MULTIPLE FACES OF ANTI-HMGCR ANTIBODY-RELATED MYOPATHIES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Pegah Masrori¹, Willem De Ridder², Jonathan Baets¹

¹Neuromuscular Reference Centre, Departement Of Neurology, Antwerp University Hospital, Edegem, BE;²Neuromuscular Reference Centre, Departement Of Neurology, Antwerp University Hospital, Edegem, BE

Background: Anti-HMGCR antibody-associated myopathies define a distinct and clinically diverse subset of idiopathic inflammatory myopathies (IIM). The most typical clinical presentation consists of subacute progressive proximal muscle weakness with moderately to severely elevated serum creatine kinase (CK) levels and myopathic electromyography findings. The muscle biopsy usually shows features of a necrotising myopathy, evident by myofibre necrosis and regeneration, with minimal or absent lymphocytic infiltrates and major histocompatibility complex I (MHC-I) expression on non-necrotic muscle fibres. As for most other IIMs, high-dose corticosteroids is considered the first-line treatment but most cases are refractory to conventional steroid monotherapy. Other immunosuppressive therapy such as methotrexate, azathioprine, rituximab and cyclophosphamide are increasingly being used. Intravenous immunoglobulin (IVIg) and plasmapheresis may be required. Associations have been described with statin exposure and some genetic risk factors. Exact pathomechanisms and potential triggers of the disorder particularly still need to be identified in patients not exposed to statins. Methods: Myositis specific antibodies (immunodot assay covering 16 auto-antibodies, including anti-HMGCR) were systematically assessed in a cohort of 40 IIM patients. Patients with anti-HMGCR antibodies were selected for specific follow-up. CK levels were repeatedly measured as well as auxiliary laboratory findings and an electromyography (EMG) was performed. Muscle biopsies were obtained for all patients from quadriceps muscle and analysed following standard histologic and immunohistochemical techniques for light microscopy. Whole-body muscle magnetic resonance imaging (MRI) was performed on a 1.5T MRI platform. Results: We present five patients with an anti-HMGCR antibody-related myopathy. Firstly, we found that the presenting symptoms are highly variable ranging from subacute severe proximal weakness to more insidious complaints linked to subtle proximal weakness. Statin use is only associated in one patient but viral infection preceding the myopathy is noted in three patients. CK levels are consistently highly elevated (above > 5000 U/L). EMG confirmed myopathic findings, muscle MRI imaging illustrated oedema in different muscle groups and muscle biopsy showed often relatively subtle abnormalities mainly consisting of fibre necrosis with myophagic reaction in the absence of florid inflammatory changes. The immune-mediated aetiology of the disease could however be confirmed immunohistochemically in all patients. Initial treatment was based on conventional steroid monotherapy with highly variable response among the patients ­reported ranging from significant clinical and biochemical improvement to complete refractoriness in others. As needed, therapy was escalated with second and third-line agents and the responses will be discussed in detail. Conclusion: Our findings highlight the clinical, histopathological and prognostic heterogeneity of anti-HMGCR antibody-related myopathies and point-out potential diagnostic and therapeutic pitfalls of this treatable myopathy. Based on our findings, we explore the role of viral infections in the pathophysiology of this disorder.

PS1Group1-023 / #1010A PLURIPOTENT STEM CELL-DERIVED MODEL OF MEROSIN DEFICIENT CONGENITAL MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Kenyon Lyon¹, Amanda Rickard², Monica Hayhurst Bennett², Uli Schmidt²

¹College Of Engineering, California Polytechnic State University, San Luis Obispo, US;²Genea Biocells, San Diego, CA, US

Background: Congenital muscular dystrophies (CMD) are a group of early onset, often very severe forms of muscle disorders. Congenital muscular dystrophy type 1A (MDC1A) accounts for about 40% of cases of CMD and has an estimated prevalence of 7/1,000,000. MDC1A is an autosomal recessive disease caused by mutations in the LAMA2 gene encoding the a2 chain of laminin-211. Laminin-211 is a major component of the skeletal muscle basement membrane that stabilizes muscle and facilitates extracellular signaling. MDC1A is a life-threatening disease characterized by hypotonia, muscle weakness, scoliosis, joint contractures and respiratory difficulties. Currently, there is no treatment available for MDC1A. Human pluripotent stem cells (hPSCs) represent a renewable source of skeletal muscle cells for disease modeling and therapeutics screening and serve as an attractive alternative to primary cultures which are more variable and only undergo limited population doublings. In these studies, MDC1A affected hPSCs were differentiated to skeletal muscle and examined for disease-relevant phenotypes. Methods: Genea Biocells’ published protocol was used to differentiate both healthy and MDC1A affected hPSCs into mature skeletal muscle myotubes and examined for MDC1A-specific defects. Results: MDC1A-affected hPSCs differentiated into multinucleated myotubes and expressed myogenic markers. We have identified a variety of clinically relevant MDC1A phenotypes that are amenable to high-throughput screening and therapeutics testing, including impaired metabolic function and mitochondrial defects. We have also detected increased activation of apoptosis-related markers in MDC1A-affected cells. Moreover, we detected defects in myogenesis through high-content imaging for myogenic markers throughout the differentiation process. Conclusion: We have developed and characterized the world’s first pluripotent stem cell-derived model of MDC1A, a powerful tool for studying MDC1A pathophysiology and for use in the development of effective treatments for CMDs.

PS1Group1-024 / #1006AN IN VITRO MODEL OF MYOTONIC DYSTROPHY TYPE 1 USING HUMAN EMBRYONIC STEM CELL-DERIVED SKELETAL MUSCLE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Ernesto Solana-Guizar¹, Samuel Labarge², Monica Hayhurst Bennett², Uli Schmidt²

¹California State University San Marcos, San Marcos, CA, US;²Genea Biocells, San Diego, CA, US

Background: Myotonic Dystrophy Type 1 (DM1) is the most common form of adult-stage onset muscular dystrophy with an estimated prevalence of 1/8,000 worldwide. Patients affected by DM1 display a range of symptoms (e.g. muscle wasting, intellectual disability, and infertility). DM1 is an autosomal-dominant, multisystemic genetic disorder characterized by CTG triplet repeat expansion in the 3’ untranslated region of the dystrophia myotonica protein kinase (DMPK) gene, with larger repeat size directly correlating to higher disease severity. The CTG repeat expansion leads to sequestration of splicing regulators (such as Muscleblind Like Splicing Regulator 1 [MBNL1]) in nuclear foci containing DMPK mRNA, and subsequent splicing defects (e.g. exon inclusions and exclusions). In this study, we differentiated unaffected control and DM1-affected human pluripotent stem cell lines to skeletal muscle using Genea Biocells’ published protocol and investigated their phenotypes with the aim to establish a clinically relevant stem cell-based disease model of DM1. Methods: Unaffected control and DM1-affected (Genea067 [1626/1773 CTG], Genea157 [1060 CTG], Genea158 [180 CTG]) human embryonic stem cell lines were differentiated into skeletal muscle (i.e. myoblasts and myotubes) according the manufacturer’s protocol and analyzed for the following: (1) Lineage commitment and differentiation kinetics of myoblasts to terminally mature myotubes was examined and quantified. (2) MBNL1 nuclear foci were visualized and quantitated by high content imaging. (3) At the molecular level, splice variants were analyzed with semi-quantitative PCR and Nanostring gene expression analysis technology. (4) We investigated cellular metabolism and energetics using Seahorse Technologies’ XF Cell Mito Stress test to understand ATP production, as well as basal and maximal respiration. Results: (1) We found that affected cells display aberrant myotube formation, as previously reported in animal models and the congenital (infant-onset) form of DM1. (2) We observed a direct correlation between disease severity and MBLN1 foci intensity. (3) We observed impaired splicing in ALPK3, ATP2A1, and CACNA1S between unaffected and Genea067 day 3 myotubes. (4) We found an inverse relationship between disease severity, i.e. number of CTG repeats, and mitochondrial respiration. Conclusion: Together, this work demonstrates the usefulness of DM1-affected human pluripotent stem cell-derived skeletal muscle to accurately model myotonic dystrophy type-1 in vitro, recapitulating known phenotypes that correlate with disease severity as well as tissue-specific mechanisms. This model represents a new and attractive tool to develop and test DM-1 muscle-targeted therapeutics.

PS1Group1-025 / #827DIMETHYLFUMARATE (DMF) DOWNMODULATES INFLAMMATION IN SKELETAL MUSCLE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Karsten Schmidt¹, Simranjeet Kaur¹, Alice Faust¹, Peter Balcarek², Jens Schmidt¹

¹Department Of Neurology, University Medical Center Göttingen, Göttingen, DE;²Department Of Trauma Surgery, Orthopaedics And Plastic Surgery, University Medical Center Göttingen, Göttingen, DE

Background: The pathogenesis of IBM is caused by degenerative and inflammatory mechanisms. Various immunosuppressive therapies have failed to show a significant beneficial effect in clinical studies. DMF is an anti-inflammatory drug used in multiple sclerosis and psoriasis. It is known to diminish the cellular stress response to pro-inflammatory stimuli and some of these effects are mediated by activation and nuclear translocation of NRF-2. This study aims to evaluate the effect of dimethylfumarate (DMF) in in vitro and in vivo model systems for inclusion body myositis (IBM). Methods: The effect of DMF was studied in vitro in a well-established pro-inflammatory cell culture model system originated from a myoblast cell line and cultured primary muscle cells on RNA and protein level using quantitative PCR, immunocytochemistry and western blotting. For in vivo studies, a previously characterized double-transgenic mouse strain was used that harbours human mutated amyloid precursor protein (APP) and presenilin (PS)-1 under muscle specific control via the creatin kinase (CK) promotor. The mice were fed by oral gavage with 15, 30 or 45μg DMF or vehicle twice per day for 14 days, followed by a pro-inflammatory stimulus via injection of LPS compared to saline into the calf. Animals were sacrificed after 48 hours and the calf muscles were analyzed by qPCR, immunohistochemistry and ex vivo flow cytometry. Results: In muscle cell cultures, DMF led to an upregulation and nuclear translocation of NRF-2. DMF diminished the muscle inflammation in the mouse model of IBM (APP/PS1 transgenic mice) upon intramuscular injection of LPS compared to controls. mRNA expression analysis by qPCR demonstrated a modest effect on pro-inflammatory cytokines in DMF treated mice compared to controls. Conclusion: The data suggest that DMF is active in skeletal muscle by translocation of NRF-2 and upregulation of associated genes. Moreover, a significant reduction of LPS-induced inflammation was noted in mice treated with DMF compared to controls in double-transgenic mice (APP/PS1).

PS1Group1-026 / #878TAMOXIFEN IN DMD: RATIONALE AND PROTOCOL FOR A MULTICENTRE, RANDOMISED, DOUBLE-BLIND, PLACEBO-CONTROLLED, PHASE 3 TRIAL

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Simone Schmidt¹, Anna-Lena Orsini¹, Patricia Hafner¹, Daniela Rubino-Nacht¹, Olivier M. Dorchies², Andres Nascimento³, U Schara⁴, Stefan Spinty⁵, Haluk Topaloglu⁶, Dirk Fischer¹

¹University Children’s Hospital Basel, Basel, CH;²School Of Pharmaceutical Sciences, University of Geneva, Geneva, CH;³Hospital Sant Joan de Déu, Barcelona, ES;⁴Universitaetsklinikum, Essen, DE;⁵Alder Hey Children’s Hospital, Liverpool, GB;⁶Hacettepe Children’s Hospital, Ankara, TR

Background: Currently, only symptomatic treatment with glucocorticoids is available in Duchenne muscular dystrophy (DMD) which have limited efficacy but many adverse effects. Most current research on therapeutics of DMD focuses on correcting the gene defect. However, as there are more than 250 mutations in the human dystrophin gene, this approach will treat only a small percentage of patients and will be expensive. Using the mouse DMD model it could be shown that tamoxifen (TAM), given orally for periods of 2 or 15 months at doses as low as 0.3mg/kg/day, results in almost full recovery of force and structure of muscles. TAM is one of the most efficacious drugs ever investigated in an animal model of DMD. Our aim is to investigate whether TAM treatment, compared to placebo, reduces the disease progression in DMD patients. Methods: We are setting up an international (France, Germany, Greece, Spain, Switzerland, United Kingdom, The Netherlands, Turkey) randomised double blind placebo controlled 48-week clinical trial with a core population (group A) of 79 ambulant 6.5 to 12 years old DMD patients that are on a stable standard treatment with glucocorticoids. Furthermore, we will include 16-20 non-ambulant patients age 10 to 16 years who do not receive glucocorticoids (parallel group B) to obtain efficacy and safety data in a broader DMD population. All patients will receive 20 mg of TAM or placebo once daily over 48 weeks. The primary outcome for ambulant DMD patients (group A) is the motor function measure (MFM) subscore D1 (standing and transfer). In the second patient population (non-ambulant patients, group B) the MFM D2 subscore is the primary endpoint, allowing extrapolation of D2 data from the group A (ambulant patient) population. Secondary outcomes include the total MFM and subscores D2 and D3, the North Star Ambulatory Assessment (NSAA), timed function tests (TFT) including 6 minute walking distance (6MWD), proximal upper limb function (PUL), and quantitative muscle testing (Grip force). In addition, to investigate whether longterm 48-week TAM treatment can slow muscle degeneration, quantitative thigh muscle magnetic resonance imaging will be performed. Results: The study aims to describe an efficacy and safety profile for tamoxifen in the treatment of DMD patients. Conclusion: According to the recommendations for trials in Duchenne and Becker muscular dystrophy released by the Committee for Medicinal Products for Human Use (CHMP) of the European Medicinal Agency (EMA/CHMP/236981/2011, Corr. 1), muscle function and muscle force should be evaluated to assess the effect of any studied intervention in muscular dystrophies. The purpose of this study is to evaluate if tamoxifen shows positive effects on muscle function and muscle force in comparison to placebo in patients with DMD. Recruitment is expected to start in May 2018.

PS1Group1-027 / #494MUSCLE HISTOPATHOLOGY IN INFANTILE DNM1L-RELATED MITOCHONDRIAL EPILEPTIC ENCEPHALOPATHY IS KEY FOR CLINICAL DIAGNOSIS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Enrico Bertini¹, Daniela Verrigni², Domenica Battaglia³, Lucia Fusco⁴, Lorenzo Figà Talamanca⁵, Rosalba Carrozzo², Daria Diodato², Adele D’Amico², Laura Papetti⁴, Daniele Ghezzi⁶, Costanza Lamperti⁶

¹Unit Of Neuromuscular Disorders, Laboratory Of Molecular Medicine, Bambino Gesu’ Children’s Hospital,, Rome, IT;²Unit Of Neuromuscular Disorders, Laboratory Of Molecular Medicine, Bambino Gesu’ Children’s Hospital,, Rome, IT;³Infantile Neuropsychiatric Unit, Fondazione Policlinico Universitario Agostino Gemelli, Rome, IT;⁴Division Of Neurology, Bambino Gesu’ Children’s Hospital,, Rome, IT;⁵Division Of Neuroradiology, Bambino Gesu’ Children’s Hospital,, Rome, IT;⁶Division Of Molecular Neurogenetics, Istituto Neurologico C. Besta, Milano, IT

Background: DNM1L (dynamin 1 like) encodes a member of the dynamin superfamily of GTPases and mediates membrane remodeling during a variety of cellular processes; in fact DNM1L has an important role in the maintenance of mitochondrial and peroxisomal morphology. Dysfunction of DNM1L is implicated in several neurological disorders and associated with either de novo-dominant mutations or compound heterozygous DNM1L mutations (MIM #603850),as well. Many patients develop refractory seizures, consistent with an epileptic encephalopathy, and thereafter show neurologic decline. The age at onset, features, and severity are variable, and some patients may not have clinical evidence of mitochondrial or peroxisomal dysfunction. Following the first description there has been increasing reports in the last 2 years on sporadic patients all affected by early onset encephalopathy with acquired microcephaly and drug-resistant seizures, progressive brain atrophy or abnormal brain development, optic atrophy, and persistent lactic acidemia related to de novo dominant-negative mutations. Methods: We collected 5 sporadic patients affected by early onset epileptic encephalopathy. Patients were studied by neuroimaging, skin and muscle biopsy and genomic DNA was analyzed by high-throughput sequencing using TruSight One panel (Illumina (San Diego, CA) in 3 patients while the remaing 2 patients were were analyzed using a custom gene panel for the screening of 230 genes associated with mitochondrial diseases.The muscle biopsies and cultures fibroblasts were processed by routine stainings, and immunofluorescence to detect the mitochondrial network arrangement. Results: Molecular genetic analysis disclosed heterozygous de novo DNML1 mutations in all 5 patients, and 3 of these mutations were novel. Unreported mutations were validated in a yeast model. Summarizing the clinical reports of the 5 patients, in all first symptoms appeared between the second and fifth year of life after normal developmental milestones occurring in the first year of life. The first manifestation consisted in prolonged treatment-resistant.generalized clonic seizures or hemiclonic seizures that shortly progressed into frequently recurrent epileptic mal status. The brain MRI showed at the beginning T2 hyperintensities in the posterior white matter regions and transient T2 hyperintensities in the cortical areas in 2 patients when performed serially. With time, the MRI showed moderate to severe global cerebral atrophy in all patients Histopathology of the muscle biopsy was revised in 4 patients and showed peculiar features: scattered fibers with a partial reduction of cytochrome c oxidase (COX) and succinate dehydrogenase (SDH) stain with aspects of polymorphic core like areas. These areas corresponded to reduced immunoreactive areas displayed by immunohistochemistry with antibodies recognizing TOMM20, defining abnormally distributed mitochondria. Biochemical spectrophotometric assay of the mitochondrial OXPHOS enzymes showed normal activities. In cultures fibroblasts we observed an increased filamentous network in mutant fibroblasts in 3 patients, while in one patient the mitochondrial network appeared as normal controls and in the last patient we observed a “chain-like” structure, not observed in controls but already reported in patients with biallelic mutations in DNM1L. Conclusion: We describe 5 sporadic patients affected by severe mitochondrial treatment-resistant seizures correlated with de novo heterozygous mutations in DNML1. The most consistent finding in all patients was a histopathological peculiar pattern

PS1Group1-028 / #731EFFECT OF A LONG-TERM TREATMENT WITH METFORMIN IN DYSTROPHIC MDX MICE: A RECONSIDERATION OF ITS THERAPEUTIC INTEREST IN DMD

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Paola Mantuano¹, Roberta F. Capogrosso¹, Francesca Sanarica¹, Maria Grazia Morgese², Michela De Bellis¹, Anna Cozzoli¹, Adriano Fonzino¹, Elena Conte¹, Giulia Maria Camerino¹, Luigia Trabace², Annamaria De Luca¹

¹Pharmacy - Drug Sciences, University of Bari “Aldo Moro”, Bari, IT;²Experimental And Clinical Medicine, University of Foggia, Foggia, IT

Background: The pharmacological stimulation of AMP-activated protein kinase (AMPK) via metabolic enhancers has recently emerged as a potential therapeutic strategy for Duchenne muscular dystrophy (DMD). Here we focused on metformin, a widely-prescribed anti-hyperglycemic drug which indirectly activates AMPK by inhibiting mitochondrial respiratory chain complex I. Recently, the potential synergistic action of metformin and NO-precursors has been proposed in clinical trials on DMD patients; a combination of metformin and L-arginine exerted positive effects on mitochondrial protein expression, in parallel slowing disease progression (NCT02516085). Despite these encouraging results, preclinical data supporting the rationale of metformin use in DMD are still poor. In addition, controversial actions of metformin on skeletal muscle have been reported. These observations made us questioning about the actual therapeutic potential of metformin as metabolic enhancer on dystrophic muscle in mdx mice and humans. In the present study, we assessed the effects of a long-term treatment with metformin in the exercised mdx mouse, characterized by severe mechanical-metabolic uncoupling and functional maladaptation, in order to gain more insight into the mechanisms of action of the drug and its potential efficacy in a metabolic state of dystrophic muscle closer to that observed in patients. Methods: Metformin was administered in drinking water at a dose of 200mg/kg for 20 weeks. A validated multidisciplinary in vivo and ex vivo ­approach was used to assess the impact of drug treatment on disease-related primary readouts. Results: We disclosed the ability of metformin to markedly ameliorate histopathology of mdx gastrocnemius (GC) muscle, significantly reducing total area of damage and, specifically, non-muscle area. This was accompanied by a significant reduction of pro-fibrotic TGF-ß1 in GC muscle (recovery score, r.s., 106%) and by a marked decrease of plasma MMP-9 level (r.s. 43%), both measured by ELISA tests. In parallel, metformin partially counteracted in vivo mdx weakness, detected by grip strength test, and significantly increased ex vivo specific twitch and tetanus of diaphragm (r.s. 28%), but not of EDL muscle, although this latter was partially protected by the treatment with respect to mechanical threshold, electrophysiological index of excitation-contraction coupling. However, these improvements were not related to a protective metformin action on dystrophic muscle metabolism, as shown by the modest effects exerted on the increase of pAMPK/AMPK ratio measured by western blot, on the expression of genes involved in mechanical-metabolic response measured by Real-time PCR, and by the lack of fast-to-slow fiber-type shift revealed by SDH staining on tibialis anterior muscle. Similar results were obtained in the milder phenotype of sedentary mdx mice. This limited efficacy could be related to the inability of metformin to increase the low muscle levels of L-arginine, L-citrulline and taurine in non-exercised/exercised mdx mice, as shown by HPLC analysis, suggesting the need of a synergic action on metabolic pathways for an efficient genetic or epigenetic effect of metformin. Conclusion: Our findings encourage the need to improve our knowledge on alternative, metabolism-independent mechanisms of action of metformin, to differently repurpose this drug for the treatment of DMD, further supporting its clinical use in combination with metabolism enhancers such as NO precursors.

PS1Group1-029 / #366IDENTIFICATION OF LATE-ONSET POMPE DISEASE AMONG HIGH-RISK POPULATION WITH NATIONWIDE SCREENING STUDY IN JAPAN

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Katsuhisa Ogata¹, Motomichi Kosuga², Eri Takeshita³, Tsuyoshi Matsumura⁴, Keiko Ishigaki⁵, Shiro Ozasa⁶, Hajime Arahata⁷, Kazuma Sugie⁸, Toshiaki Takahashi⁹, Satoshi Kuru¹⁰, Michio Kobayashi¹¹, Hiroto Takada¹², Ayako Hattori¹³, Masanori P. Takahashi¹⁴, Nobuyuki Tanaka¹⁵, Takashi Kimura¹⁶, Michinori Funato¹⁷, Torayuki Okuyama¹⁸, Hirofumi Komaki¹⁹

¹Institute Of Clinical Research / Department Of Neurology, National Hospital Organization Higashisaitama Hospital, Hasuda, Saitama, JP;²Center For Lysosomal Storage Diseases / Department Of Clinical Laboratory Medicine / Division Of Medical Genetics, National Center for Child Health and Development, Setagaya, Tokyo, JP;³Department Of Child Neurology, National Center of Neurology and Psychiatry, Kodaira, Tokyo, JP;⁴Neurology, National Hospital Organization Toneyama National Hospital, Toyonaka, JP;⁵Department Of Pediatrics, Tokyo Women’s Medical University, Shinjuku, Tokyo, JP;⁶Department Of Pediatrics, Kumamoto University, Kumamoto, JP;⁷Department Of Neurology, National Hospital Organization Omuta Hospital, Omuta, Fukuoka, JP;⁸Department Of Neurology, Nara Medical University, Kashihara, Nara, JP;⁹Department Of Neurology, National Hospital Organization Sendai-Nishitaga National Hospital, Sendai, Miyagi, JP;¹⁰Department Of Neurology, National Hospital Organization Suzuka National Hospital, Suzuka, Mie, JP;¹¹Department Of Neurology, National Hospital Organization Akita National Hospital, Yurihonjo, Akita, JP;¹²Department Of Neurology, National Hospital Organization Aomori Hospital, Aomori, JP;¹³Department Of Neonatology And Pediatrics, Nagoya City University, Nagoya, Aichi, JP;¹⁴Department Of Neurology, Osaka University, Suita, Osaka, JP;¹⁵Department Of Neurology, National Hospital Organization Shimoshizu National Hospital, Yotsukaido, Chiba, JP;¹⁶Department Of Neurology, National Hospital Organization Asahikawa Medical Center, Asahikawa, Hokkaido, JP;¹⁷Department Of Pediatrics, National Hospital Organization Nagara Medical Center, Gifu, JP;¹⁸Center For Lysosomal Storage Diseases / Department Of Clinical Laboratory Medicine, National Center for Child Health and Development, Setagaya, Tokyo, JP;¹⁹Department Of Clinical Research Promotion / Department Of Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, Tokyo, JP

Background: Late-onset Pompe disease (LOPD) is a rare, but treatable metabolic myopathy caused by deficiency of acid alpha-glucosidase (GAA). LOPD is characterized by progressive muscle weakness and/or respiratory failure, but some LOPD patients could be overlooked due to lack of typical signs. To evaluate the utility of dried blood spots (DBS) in the diagnostic work-up and assess the prevalence of LOPD within a Japanese high-risk population, we prospectively screened for LOPD in a Japanese cohort of undetermined myopathy patients aged one year or older with muscle weakness and/or elevated serum creatine kinase levels. Methods: Sixteen neuromuscular center hospitals, members of Muscular Dystrophy Clinical Trial Network (MDCTN), joined the Pompe disease high risk screening study in Japan (PHiRS-J). We tested GAA activity with DBS as first screening method. Patients with reduced GAA activity in DBS were re-analyzed for enzyme activity in lymphocytes, and investigated for GAA gene mutations. Results: Among 164 patients enrolled, two were incompatible with inclusion criteria. Eleven patients showed reduced GAA activity with DBS. Of these patients, three showed normal GAA enzyme activity in lymphocytes; five were revealed as pseudodeficiency; three with confirmed reduction of GAA activity in lymphocytes were identified to have homozygous or compound heterozygous mutations of the GAA gene. Conclusion: In a Japanese high-risk cohort, we found a prevalence of LOPD around 2%. This study suggests that screening of GAA activity with DBS is useful to diagnose patients with LOPD in a high-risk population.

PS1Group1-030 / #496CLINICAL COURSE OF ADULT POMPE DISEASE PATIENTS WHO DID NOT START OR DISCONTINUED ENZYME REPLACEMENT THERAPY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Harmke A. Van Kooten¹, Laurike Harlaar¹, Nadine A.m.e. Van Der Beek¹, Pieter A. Van Doorn¹, Ans T. Van Der Ploeg², Esther Brusse¹

¹Department Of Neurology, Center For Lysosomal And Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, NL;²Department Of Paedicatrics, Center For Lysosomal And Metabolic Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, NL

Background: Since the introduction of enzyme replacement therapy (ERT) for Pompe disease in 2006, the disease course of patients who did not start ERT, or who discontinued ERT has rarely been described. However, insight in the clinical course of these patients adds to the implementation and further development of guidelines on starting and stopping of ERT in adult Pompe patients. Methods: From our cohort of adult Pompe patients (n=127), we describe the clinical course of two groups; 1) those who have never been treated with ERT and 2) patients in whom ERT was discontinued for various reasons.

Figure 1 shows an overview of the study population. In group 1 (no ERT; n=15) 10 patients had no or only very mild symptoms; these patients remained clinically stable during follow-up (median 5.8 years, range 0.6 – 11.4 years). Two patients with moderate symptoms of Pompe disease preferred not to start ERT and three patients were too severely affected to start ERT or had life threatening comorbidity. In group 2 (discontinuation of ERT; n=24) ERT was ceased in 14 patients after death. In 10 patients, ERT was discontinued for other reasons: in five patients because of infusion related reactions, two patients chose to stop ERT because they experienced a high burden of the treatment regime, in one severely affected patient we stopped because of continued clinical deterioration under ERT, one patient stopped ERT to undergo treatment for lymphoma and in one patient we ended ERT because of non-compliance. Median treatment duration of the 10 patients who discontinued ERT was 2.1 years (range 0.3 – 14.6 years). ERT had been effective, improving or stabilizing motor and pulmonary function, in eight of them. For three patients sufficient follow up data after treatment cessation was available, with follow up duration of 1.3 – 8.0 years. After discontinuation of ERT we did not observe accelerated disease progression beyond the estimated natural progression rate in these three patients. Conclusion: Pompe patients with no or mild symptoms may show a stable disease course for many years, indicating that starting ERT could likely be postponed in this group of patients, under careful follow up. Importantly, in patients who discontinued ERT for various reasons, we did not observe accelerated disease progression beyond estimated disease progression rate. Both findings facilitate the process of shared decision making when considering start or discontinuation of ERT in adults with Pompe disease.

PS1Group1-031 / #314PROLONGED EXERCISE TEST IN PATIENTS WITH HISTORY OF THYROTOXICOSIS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Cheng-Yin Tan¹, Hui-Ting Tan², R. Jeyakantha Ratnasingam², Khean-Jin Goh²

¹University of Malaya, Kuala Lumpur, MY; ²University of Malaya, Kuala Lumpur, MY

Background: Thyrotoxic periodic paralysis (TPP) is characterised by recurrent episodes of reversible, severe proximal muscle weakness associated with hypokalaemia and hyperthyroidism. TPP is common in Asians and is a secondary hypokalaemic periodic paralysis, with clinical and electrophysiological characteristics similar to primary hypokalaemic periodic paralysis. Prolonged exercise test (PET) is an easy, non-invasive test evaluating abnormal muscle membrane excitability in periodic paralyses. Results of PET studies in TPP patients on their thyroid status have been variable with one study showing normalization of response while another did not. We aim to evaluate patients with history of thyrotoxicosis with PET and correlate it with the thyroid status. Methods: We prospectively recruited 35 patients with history of thyrotoxicosis (regardless of whether they had TPP) from Endocrinology Clinic. Of the 35 patients, 18 were hyperthyroid, 17 euthyroid or hypothyroid. The thyroid status was determined biochemically from the latest thyroid function test. All patients underwent PET as described by McManis. Compound muscle action potential (CMAP) amplitudes post-exercise were compared against pre-exercise amplitudes and recorded as percentage of mean baseline CMAP amplitude. Results: Compared to 17 euthyroid or hypothyroid patients, significant time-dependent declines in CMAP amplitudes at 20 minutes (88.3±11.9% vs 96.7±5.2%; p=0.012), 25 minutes (88.8±12.9% vs 96.4±8.6%; p=0.047) and 30 minutes (88.1±13.0% vs 97.1±10.3%; p=0.030) after exercise were observed in hyperthyroid patients. The calculated mean greatest decrement from immediate post exercise CMAP amplitudes were 22.5±13.0% in hyperthyroid patients and 15.5±13.0% in euthyroid/hypothyroid patients. Conclusion: CMAP decrement on PET was significantly greater in hyperthyroid patients compared to euthyroid/hypothyroid patients even without a history of TPP. Muscle membrane excitability is highly influenced by thyroid hormone level. TPP results from increased levels of thyroid hormone activity in genetically susceptible patients.

PS1Group1-032 / #882CLINICAL AND HISTOPATHOLOGICAL FINDINGS IN MYOTONIC MUSCULAR DYSTROPHY TYPE 2: RETROSPECTIVE REVIEW OF 50 DNA-CONFIRMED CASES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Bhaskar Roy¹, Qian Wu², Charles Whitaker³, Kevin Felice³

¹Neurology, Yale University, New Haven, CT, US;² Pathology, University of Connecticut, Farmington, CT, US;³ Neurology, Hospital for Special Care, New Britain, CT, US

Background: Myotonic dystrophy type 2 (DM2) is an autosomal dominant multisystem disorder causing a progressive myopathy and myotonia due to (CCTG)n repeat expansion in intron 1 of the CNBP gene in chromosome 3q21. Focused study on a US-based population is limited. Methods: We reviewed the clinical presentation, muscle strength grading by MRC, Jamar hand grip dynamometry, electromyography (EMG), creatine kinase (CK) values, forced vital capacity (FVC), muscle histopathology, CCTG repeat expansion (bp) size for DM2 patients from 1992 to 2015 evaluated at the Muscular Dystrophy Care Center at Hospital for Special Care, CT, USA. Muscle histopathology was graded based on myofiber size variability, internal nucleation, pyknotic nuclear clumps, necrosis, myofiber hypertrophy and atrophy. Results: Fifty patients with DM2 were included in this study. Forty-six patients had positive genetic study and 4 were affected family members. Age of symptom onset ranged from 15 to 72 years (48.58 ± 13.12). Duration between symptom-onset and initial evaluation ranged from 1 to 42 years (7.3 ± 9.37). Majority of the patients (64%) had proximal lower extremity symptoms as the initial presentation. Ten patients did not have any weakness and 17 patients had severe weakness based on a composite MRC scoring system. Hip flexors were the most frequently and severely affected muscles, followed by knee extensors and elbow extensors. About 30% patients had finger muscles involvement or ankle dorsiflexion weakness. Though most patients had a milder and stable disease course, we noted significant progression of weakness in a few patients. For composite MRC score, the rate of mean decline per year was 0.91 ± 0.79. For hip flexors, the rate of mean decline in MRC score per year was 0.21 ± 0.19. FVC (% predicted) in 32 (64%) patients ranged from 36 to 100% (mean, 81.1 ± 18.3%). CK values in 36 patients ranged from 20 to 2000 units/L (mean, 581.7 ± 449.3). Nine patients had clinical myotonia and 35 patients had myotonia on EMG. Among the muscles examined, biceps and tibialis anterior had myotonic discharges most frequently, 91.6% and 85.7% times respectively. No association was noted between the presence of myotonia in EMG and muscle weakness. We noted significant correlation of severity of histopathology with weakness. There was no correlation between CCTG repeat numbers with age of onset, weakness, disease progression, CK value, hand grip strength or histopathological severity. Among systemic involvement, 24 patients had cataracts (48%) and 7 patients had hearing loss. Five patients had symptomatic cardiac arrhythmia and 3 of them required pacemaker. Eleven patients had diabetes and 8 patients had hypothyroidism. Conclusion: This large cohort of DM2, evaluated over a 24-year-period in a single center, showed variation in clinical presentation and disease severity.

PS1Group1-033 / #327ASCERTAINMENT OF THE ADULT PATIENT COHORT WITH MITOCHONDRIAL DISEASE IN GLASGOW

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Maria Elena Farrugia¹, Cheryl Longman², Lesley Snadden², Grainne S. Gorman³, Andrew M. Schaefer³, Robert W Taylor³, Yi Shiau Ng³, Douglass M. Turnbull³, Robert Mcfarland³, Richard K. Petty⁴

¹Neurology, Institute of Neurological Sciences, Glasgow, GB;²Genetics, West of Scotland Regional Genetics Service, Glasgow, GB;³Institute Of Neuroscience, Newcastle University Wellcome Trust Centre for Mitochondrial Research, Newcastle upon Tyne, GB;⁴Neurology, Institute of Neurological Sciences, Glasgow, GB

Background: Mitochondrial disorders are caused by gene mutations in nuclear or mitochondrial (mt) DNA, encoding structural mitochondrial proteins or proteins involved in mitochondrial function. Patients with mitochondrial disease have diverse phenotypes. Patients may present with ptosis and ocular motility disorders (which may be misdiagnosed as ocular myasthenia). Some suffer from myopathy, diabetes, migraine, deafness and seizures (common red flags for general neurologists). Others may present with ataxia, neuropathy, cognitive impairment, psychosis, or intestinal pseudo-obstruction. These symptoms may not be immediately recognised as part of the disease spectrum and may lead to mis-management. The muscle clinic in Glasgow captures a population of circa 2 million. We have a longstanding collaboration with the NHS Highly Specialised Service for Mitochondrial Disease and Wellcome Centre for Mitochondrial Research in Newcastle, where we refer muscle pathology and patients to help us with the molecular diagnoses and patient management. We wanted to determine the population of molecularly confirmed mitochondrial patients attending the adult muscle clinic in Glasgow and characterise their phenotypes. Methods: We retrospectively identified 57 adult patients (20 families) with molecularly confirmed mitochondrial mutations from a neuromuscular database held in Glasgow. Results: The cohort included 25 patients with m. 3243 A>G mutation (14 families), 9 with the m. 8344 A>G mutation (2 families), 11 with sporadic large-scale mtDNA deletions, 3 with POLG dominant mutations and 2 with YARS2 recessive mutations (reported in previous publication; Sommerville et al, JAMA Neurol 2017). Another 7 had various mutations (including mutations in mt-transfer RNA, defects in complex I, complex III, mt-ATP 6, a patient with m. 7497 G>A mutation with a contractural limb-girdle phenotype, and a patient with multiple mitochondrial deletions for which no nuclear defect has been identified). The common symptoms within the m. 3243 A>G cohort included diabetes, deafness and migraine. Four patients had sustained stroke-like episodes (including 2 from the same pedigree with recurrent events and including one which led to her demise). Within the m. 8344 A>G cohort, symptoms included hearing loss, myopathy and exercise intolerance. Two patients (mother and son) had abnormal EEGs with lateralising epileptiform features but no clear clinical seizures or myoclonus. Within the single large-scale mtDNA deletions all had ptosis with progressive external ophthalmoplegia (PEO), 2 had pacemakers, 2 had cognitive difficulties and one required feeding through a gastrostromy tube. All 3 patients with POLG mutations had ptosis with PEO and myopathy. One patient had an episode of intestinal pseudo-obstruction which settled with conservative management. We finally discuss the case of a lady with m. 3243 A>G mutation, who succumbed to complications from a stroke-like episode and the difficulties pertaining to her management. Such patients can present with super-refractory epileptic seizures, requiring aggressive management. We discuss the difficult decisions pertaining to prophylactic anti-seizure medication for her family members, who harbour the mutation at high heteroplasmy levels in urine and muscle. Conclusion: Patients with mitochondrial disorders suffer from a complex multi-system disease. Awareness of this is pertinent when assessing mitochondrial patients, discussing diagnosis and prognosis with patients and their families. Their management requires a multidisciplinary approach.

PS1Group1-034 / #373RESTING-STATE FMRI SHOWS ALTERED DEFAULT-MODE NETWORK FUNCTIONAL CONNECTIVITY IN DUCHENNE MUSCULAR DYSTROPHY PATIENTS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Nathalie Doorenweerd¹, Mischa De Rover², Chiara Marini-Bettolo³, Kieren G. Hollingsworth⁴, Erik H. Niks⁵, Jos G.m. Hendriksen⁶, Hermien E. Kan¹, Volker Straub⁷

¹C.j. Gorter Center For High Field Mri, Leiden University Medical Center, Leiden, NL;²Clinical Psychology Unit, Leiden University, Leiden, NL;³John Walton Muscular Dystrophy Research Center, Newcastle University, Newcastle Upon Tyne, GB;⁴Newcastle Magnetic Resonance Centre, Newcastle University, Newcastle Upon Tyne, GB;⁵Neurology, Leiden University Medical Center, Leiden, NL;⁶Neurological Learning Disabilities, Kempenhaeghe Epilepsy Center, Heeze, NL;⁷John Walton Muscular Dystrophy Research Centre, Newcastle University, Institute of Genetic Medicine, Newcastle Upon Tyne, GB

Background: Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disorder caused by mutations in the dystrophin encoding DMD gene. Dystrophin is expressed in muscle but also in brain and difficulties with attention/inhibition, working memory and learning are well described. Reduced functional connectivity in the motor cortex has been reported in DMD. However, the default mode network (DMN) remains unexplored despite being involved in switching between different stages of attention as well as information processing and self-reflection. Therefore, the aim of this study was to determine if there are differences in DMN connectivity between DMD and controls. Methods: Thirty-three DMD and twenty-four male age matched controls were recruited and scanned at two clinical sites (LUMC and NU). T1-weighted anatomical scans and resting state functional scans were obtained on a 3 Tesla Philips Achieva. FSL v.5.0.8 was used for all analyses which were performed in accordance with recent FSL recommendations, including ICA-AROMA motion correction.The DMN was first identified in the controls. Statistics were performed with FSL RANDOMISE to test for differences between DMD and controls in the DMN and the visual network, with age as covariate and threshold-free cluster enhancement multiple comparison correction. Results: There was significant hyper-connectivity in the precuneus and hippocampus and additional connections with the right thalamus in relation to the DMN in DMD compared to controls. This may be related to the often impaired learning abilities in DMD. Additional connectivity is also found in the sensori-motor cortex. As DMD is hallmarked by progressive muscle wasting, altered connectivity in this region is not surprising but the relationship with the default mode network is unclear. Reduced grey matter volume and perfusion known to be present throughout the brain in DMD could lead to lower signal to noise ratio which could have a confounding effect on the comparison. Therefore, the visual network was assessed as negative control and indeed, no significant differences were found between DMD and controls. Conclusion: Altered DMN connectivity was found in DMD with both hyper-connectivity within the DMN and reconfiguration of the network to include additional brain regions. As the DMN in general is active during rest and inactive during tasks, it will be important to assess in DMD if this extended DMN, which includes greater parts of the precuneus, hippocampus and thalamus, is also inactivated when a task is performed. If so, this may help explain the incidence of attention/inhibition, working memory and learning difficulties in DMD.

PS1Group1-035 / #930SPECIFIC MUTATIONS IN MYBPC1 CAUSE MYOPATHY AND “MYOGENIC TREMOR”

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Sandra Jackson¹, Jochen Schaefer¹, Annika Saak¹, Janis Stavusis², Baiba Lace³, Janelle Geist⁴, Inna Inashkina², Dita Pelnena², Sander Pajusalu⁵, Nathan Wright⁶, Aikaterini Kontrogianni-Konstantopoulos⁴, Carsten G. Bönnemann⁷

¹Neurology, Uniklinikum C.G.Carus, Dresden, DE;²Latvian Biomedical Research Centre, Riga, LV;³Centre Hospitalier Universitaire de Quebec, Quebec, CA;⁴University of Maryland School of Medicine, Baltimore, US;⁵Tartu University Hospital, Tartu, EE;⁶James Madison University, Harrisonburg, US;⁷NIH Porter Neuroscience Research Center, Bethesda, MD, US

Background: Myosin-binding protein C1, a sarcomeric protein, is thought to stabilize the thick filaments interacting with myosin, actin and creatine kinase. To date, only few MYPBC1-mutations have been reported in human disease and lead to autosomal-dominant distal arthrogryposis and autosomal-recessive lethal contracture syndrome. Methods: We describe two multi-generation families with non-progressive, proximal and axial weakness, mild spinal rigidity and myalgia. In both families, postural fast-frequency tremor of hands and tongue segregated with the disease. Pathogenic mutations identified by panel sequencing were introduced into truncated GST-tagged recombinant mutant and wild-type proteins. Binding of the mutant protein to myosin was assessed with overlay and immunoblotting assays, and 3D-modelling of the MYBPC1-myosin interaction was performed. Results: Two mutations located in adjacent codons in the M-motif of MYPBC1 and segregating with the disease in both families, demonstrated significantly increased binding of the mutant to myosin compared to the wild-type protein. 3D-modelling and MD-simulation implicated increased electrostatic interactions of MYBPC1 with myosin. Neurophysiological testing excluded a peripheral generator of the tremor. Conclusion: The mutations, which segregated with the disease in both families were predicted by MD-modelling to increase the binding affinity of MYBPC1 to myosin. This was confirmed with in vitro binding-assays. Presumably, cross-bridge cycling of actin and myosin will be affected thus reducing force generation. The tremor associated with the disease was shown to be neither of peripheral nor of central origin, because MYBPC1 is exclusively expressed in muscle sarcomeres. Thus we postulate a novel class of tremor which we designated “myogenic tremor”.

PS1Group1-036 / #957DIAGNOSTIC APPROACH TO CHRONIC PROGRESSIVE EXTERNAL OPHTHALMOPLEGIA – FROM CLINICAL EVALUATION TO GENETIC CONFIRMATION

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Biruta Kierdaszuk¹, Magdalena Kaliszewska², Katarzyna Tonska², Ewa Bartnik², Anna M. Kaminska¹, Anna Kostera-Pruszczyk¹

¹Department Of Neurology, Medical University of Warsaw, Warsaw, PL;²Institute Of Genetics And Biotechnology, Faculty Of Biology, University of Warsaw, Warsaw, PL

Background: Mitochondrial encephalomyopathies comprise a group of heterogeneous disorders which result from impaired oxidative phosphorylation. The respiratory chain complexes present in mitochondria are dependent both on mitochondrial (mtDNA) and nuclear genome (nDNA). Different age of onset, various clinical presentations and individual course of the disease make the diagnosis of mitochondrial disorders challenging. From a variety of symptoms progressive external ophthalmoplegia (PEO) seems to be the most common. The aim of this study was the clinical and genetic characteristics of Polish patients with progressive external ophthalmoplegia. Methods: Clinical, electrophysiological, neuroradiological and morphological data of 72 patients aged 11 to 76 years were analyzed. The muscle specimens were assessed on light and electron microscopy using routine procedures. Genetic studies of mtDNA were performed in all patients. Among nDNA genes POLG was studied in 26 patients, TWNK (C10orf2) in 3 patients and RNASEH1 in 2 patients. Results: 24 patients with ptosis and PEO were included to chronic progressive external ophthalmoplegia (CPEO) group and 19 with ptosis, PEO and limb or trunk muscles’ weakness to CPEO+ group. There were 22 patients with PEO and the central nervous system impairment classified as mitochondrial encephalomyopathy (ME), 6 patients with Kearns-Sayre syndrome (KSS) and one patient with sensory ataxic neuropathy, dysarthria, ophthalmoparesis (SANDO) syndrome. 7 patients had relatives with similar symptoms. Among various diagnostic procedures electromyography showed myopathic changes in the majority of cases. Ragged-red fibers were present in most of muscle biopsies. Magnetic resonance imaging showed atrophied ocular muscles in patients with pure myopathic phenotype and revealed cortical and subcortical atrophy in those with the central nervous system involvement. In single cases magnetic resonance spectroscopy showed elevated lactates in the brain. Genetic studies of mtDNA proved already known single or multiple mtDNA deletions in all patients and in most cases they were detected in the muscle tissue. Genetic analysis of nDNA genes confirmed mutations in POLG gene in 6 patients. There were 3 CPEO patients with p.[Arg309Leu];[Gln968Glu], p.[Ala518Thr];[=] and p.[Trp748Ser];[Ser998Pro] mutations, and 2 CPEO+ patients with p.[Thr251Ile;Pro587Leu];[Thr251Ile;Pro587Leu] and p.[Thr251Ile;Pro587Leu];[Lys1191Asn] mutations. In patient with SANDO syndrome the mutation p.[Arg290Cys];[Arg309Cys] in POLG gene was confirmed. Additionally the analysis of the TWNK (C10orf2) gene proved the mutation p.[Arg374Gln];[=] in 2 CPEO patients and one CPEO+ patient. Assessment of RNASEH1 gene revealed homozygous variant p.[Gly165Arg];[Gly165Arg] in two siblings with ME. Conclusion: Detailed patients’ history and careful assessment of family history are essential in the diagnostic work-up. Morphological evaluation of the muscle biopsy as well as magnetic resonance imaging are also important. Genetic studies of both mtDNA and nDNA are necessary for final diagnosis of chronic progressive external ophthalmoplegia and its genetic counseling.

PS1Group1-037 / #473FEMALE FERTILITY IN MYOTONIC DYSTROPHY TYPE 1 AND 2

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Olesja Parmova¹, Iva Srotova¹, Monika Hulova¹, Eva Vlckova¹, Livie Mensova², Martina Podborska³, Petra Stradalova¹, Eva Kralickova¹, Igor Crha⁴, Radim Mazanec², Stanislav Vohanka¹, Josef Bednarik¹

¹Neurology, University Hospital Brno, Brno, CZ;²Neurology, Motol University Hospital, Prague, CZ;³Clinical Biochemistry, University Hospital Brno, Brno, CZ;⁴Obstetrics And Gynecology, University Hospital Brno, Brno, CZ

Background: Myotonic dystrophy (DM) represents the most common type of muscular dystrophy in adult age. Clinical signs and symptoms in type 1 (DM1) and type 2 (DM2) overlap. DM is a multisystem disorder that, among others, affects endocrine system and thus may have a negative impact on fertility. Female fertility impairment has already been shown in patients with DM1, while only few data are available on DM2 patients. The aim of our study was to compare the fertility characteristics in women with DM1, DM2 and healthy volunteers. Methods: Patients: 22 reproductive-age females (mean age 34.8 ± 8.0) with DM2 and 18 reproductive-age females with DM1 (mean age 33.9 ± 6.8) were included in this case control study. With respect to significant differences between these two groups in several relevant parameters (e.g. number of pregnancies), particular control groups were created for each of them: DM2 control group consisted of 22 age-matched healthy controls (mean age 34.1 ± 7.5) and DM1 control group of 18 age-matched healthy controls (mean age 33.2 ± 7.0). Methods: All participants completed a set of questionnaires used to evaluate fertility. Results: The time to get pregnant was significantly longer in DM1 females when compared with appropriate controls (p < 0.01) and the miscarriages were more frequent in this DM group (p = 0.02). Females with DM1 also had more often irregular menstrual cycle (p = 0.02) which was more frequently controlled by oral contraceptives in this group. Furthermore, patients with DM1 had higher incidence of uterine myomas and more frequently underwent abdominal gynecologic surgery (p < 0.01). In comparison with healthy controls, an unsignificant trend to more frequent investigation of fertility problems and their treatment was observed in women with DM1 (p = 0.08). Females with DM2 have more frequent miscarriages (p = 0.04) as the only statically significant difference when compared with healthy controls. Conclusion: Our study confirmed clear fertility impairment in women with DM1 and showed less pronounced (but still significant) fertility changes also in female patients with DM2.

PS1Group1-038 / #340EFFECT OF AHK, A NOVEL MODULATOR OF RYANODINE RECEPTORS, IN DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Haizpea Lasa Fernandez¹, Garazi Aldanondo², Jaione Lasa Elgarresta², Aitziber Irastorza³, Jose Ignacio Miranda³, Jesus Maria Aizpurua³, Adolfo López De Munain⁴, Ainara Vallejo Illarramendi²

¹Department Of Neuroscience, University of the Basque Country, Leioa, ES;²Neuroscience Area, Biodonostia Research Institute, Donostia, ES;³Faculty Of Chemistry, University of the Basque Country, Donostia, ES;⁴Neurology, Hospital Donostia, Donostia, ES

Background: In the mdx mouse model of Duchenne muscular dystrophy (DMD) the sarcoplasmic reticulum ryanodine receptor (RyR) is abnormally nitrosylated and this leads to calstabin depletion from the protein complex and subsequent calcium leak through the channel. RyR stabilizers, such as S107, enhance RyR-calstabin binding preventing calcium leak and the consequent damage. Methods: To study the in vitro effect of AHK we have evaluated RyR-calstabin colocalization using in situ proximity ligation assay (PLA) in dystrophin-deficient human myotubes treated overnight with AHK150 nM. We also have determined intracellular calcium levels in these myotubes using Fura-2AM, a ratiometric calcium indicator. For the in vivo studies, we have administered AHK to male mdx mice in the drinking water for 5 and 12 weeks. We have determined forelimb strength using a grip strength meter. Diaphragm muscle sections were used for histopathological analysis using immunofluorescence. The percentage of central nucleation was determined as a marker of muscle degeneration/regeneration. To study cardiac and cognitive deficits in vivo, we have used 4 month-old mdx mice. We have analyzed cardiomyocyte damage after beta-isoproterenol challenge, using Evans blue dye (EBD) uptake, as an indicator of cardiomyocyte plasma membrane integrity. Finally, we have measured mdx cognitive deficits by tracking the movement after an acute stress produced by a brief restrain. Results: The present work shows that treatment of 1 month-old mdx mice during 5 and 12 weeks with AHK, a novel RyR modulator, improves the dystrophic phenotype of mdx mice. After the treatment during 5 weeks the histopathological and biochemical evidence of skeletal muscle damage is reduced and the strength is improved. Since cardiac and cognitive impairments manifest in older mice, the treatment is prolonged for 12 weeks. Once we characterized the behavioral phenotype of mdx mice, we observe improvements in treated mice regarding to heart function and behavioral deficits. Conclusion: Overall, our results demonstrate that AHK is effective in improving not only skeletal muscle dystrophic phenotype but also the impairments observed in cardiac muscle and CNS in the mdx mouse model of DMD. Thus, they support AHK as a potential therapeutic drug to prevent the progression of muscular, cardiac and neurological defects in DMD patients.

PS1Group1-039 / #380ASPIRO PHASE 1/2 GENE THERAPY TRIAL IN X-LINKED MYOTUBULAR MYOPATHY (XLMTM): PRELIMINARY SAFETY AND EFFICACY FINDINGS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Nancy Kuntz¹, Perry B. Shieh², Barbara Smith³, Carsten G. Bönnemann⁴, James J. Dowling⁵, Michael W. Lawlor⁶, Wolfgang Müller-Felber⁷, Mo Noursalehi⁸, Sal Rico⁸, Laurent Servais⁹, Suyash Prasad⁸

¹Ann & Robert H Lurie Children’s Hospital of Chicago, Chicago, IL, US;²University of California, Los Angeles, Los Angeles, CA, US;³University of Florida, Gainesville, FL, US;⁴NIH Porter Neuroscience Research Center, Bethesda, MD, US;⁵Hospital for Sick Children, Toronto, ON, CA;⁶Medical College of Wisconsin, Milwaukee, WI, US;⁷Klinikum der Universität München, Munich, DE;⁸Audentes Therapeutics, San Francisco, CA, US;⁹Hopital Armand Trousseau, Paris, FR

Background: X-linked myotubular myopathy (XLMTM) is a rare disease caused by mutations in the MTM1 gene and characterized by profound muscle weakness, respiratory failure and early death. A retrospective chart review of 112 boys with XLMTM (RECENSUS study [Beggs, 2017]) showed overall mortality of 44%. Additional natural history data are being collected in an ongoing, prospective, non-interventional, run-in study of male patients with XLMTM (the INCEPTUS study), to serve as a longitudinal baseline and within-patient control for the ASPIRO clinical study. Methods: Phase 1/2, open-label, randomized, ascending dose study to evaluate the safety and preliminary efficacy of an investigational gene therapy product (AT132) in patients with XLMTM. AT132 (rAAV8-Des-hMTM1) is designed to deliver functional copies of the MTM1 gene to skeletal muscle cells. Approximately 12 XLMTM patients less than 5 years of age are planned to be randomized into three ascending dose cohorts (n=4 per cohort) to receive a single AT132 administration (n=3) or to act as a delayed treatment control (n=1). Treatment-randomized Cohort 1 patients received an intravenous infusion of 1x10¹⁴ vector genomes (vg) per kg of AT132.

Results: A total of 6 adverse events (AEs) were reported, of which 3 were deemed probably or possibly related to drug and 2 were deemed serious AEs (SAEs). Both SAEs occurred in Patient 3, who is responding to intravenous steroids and supportive care. Efficacy assessments have shown notable improvements in both the Children’s Hospital of Philadelphia Infant Test of Neuromuscular Disorders (CHOP-INTEND) scale and maximal inspiratory pressure (MIP) (Table 1). Whereas age-appropriate motor milestones had not been achieved at baseline, by week 12, Patient 1 (aged 1 year) had acquired several new developmental skills, including the ability to control head movements, roll over by himself and sit unassisted for >5 seconds. Patient 2 was observed for 8 weeks, and Patients 3 and 4 (Control) were observed for 4 weeks. All treated patients have demonstrated improvements in airway clearance and secretion management as evidenced by changes in the Parental Global Impression of Secretion Improvement and Severity Scales. Clinical Global Impression of Improvement reports demonstrate increased limb and trunk strength, improved velocity and accuracy of movement and increased loudness during vocalization and crying, improving their ability to communicate. Conclusion: Preliminary data from cohort 1 of the ASPIRO study are encouraging and based on these observations, the current plan is to enroll three additional patients at this dose level.

PS1Group1-040 / #442MR IMAGING OF RESPIRATORY MUSCLE DYSFUNCTION IN POMPE DISEASE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Laurike Harlaar¹, Pierluigi Ciet², Alice Pittaro², Piotr A. Wielopolski², Harmke A. Van Kooten¹, Nadine A.m.e. Van Der Beek¹, Esther Brusse¹, Ans T. Van Der Ploeg³, Marleen De Bruijne⁴, Harm A.w.m. Tiddens⁵, Pieter A. Van Doorn¹

¹Department Of Neurology, Center For Lysosomal And Metabolic Diseases, Erasmus MC, Rotterdam, NL;²Department Of Radiology And Nuclear Medicine, Erasmus MC, Rotterdam, NL;³Department Of Paediatrics, Division Of Metabolic Diseases And Genetics, Center For Lysosomal And Metabolic Diseases, Erasmus MC-Sophia, Rotterdam, NL;⁴Biomedical Imaging Group Rotterdam, Departments Of Radiology And Medical Informatics, Erasmus MC, Rotterdam, NL;⁵Department Of Paediatrics, Respiratory Medicine And Allergology, Department Of Radiology And Nuclear Medicine, Erasmus MC, Rotterdam, NL

Background: Adult patients with Pompe disease present with a spectrum of symptoms, mainly characterized by progressive limb-girdle weakness and decreased pulmonary function. Limb-girdle weakness mostly improves or stabilizes after start of enzyme replacement therapy (ERT). Pulmonary function often benefits less well from ERT and may continue to deteriorate. Standard pulmonary function tests only give limited insight in the pathophysiological mechanisms of the pulmonary insufficiency. MRI enables to visualize the diaphragmatic and chest wall movements simultaneously. In a previous study, MRI showed very limited movement of the diaphragm in ten Pompe patients with severe respiratory muscle weakness. Our aim is to study diaphragmatic function in a large group of Pompe patients and to investigate the best outcome measures to evaluate the function of the diaphragm. Methods: We perform spirometer-controlled MRI scans in patients with Pompe disease and sex- and age-matched healthy controls. We acquired dynamic sagittal 2D images in left and right mid hemi-diaphragm during forced inspiration. After manual segmentation of these images, we measured the cranial-caudal and anterior-posterior distance, lung area, diaphragm height, diaphragmatic shape factor and diaphragm slope (figure). We calculated the ratios between maximal inspiration and maximal expiration. We tested intra- and interobserver variability of the measurements, and differences between Pompe patients and controls. Results: In our ongoing study we have now included 34 patients with Pompe disease (age range 15-70 years) with varying disease severity, and 18 controls. All thorax-related measurements showed a high reliability (intraclass correlation coefficient > 0.9). Diaphragm-related measurements showed a larger intra- and interobserver variability. On the right side, mean cranial-caudal ratio was 1.4 in Pompe patients and 1.7 in controls (p<0.01); mean lung area ratio was 2.1 in Pompe patients and 2.5 in controls (p<0.01). On the left side, mean cranial-caudal ratio was 1.4 in Pompe patients and 1.6 in controls (p<0.01); mean lung area ratio was 1.9 in Pompe patients and 2.1 in controls (p=0.03). In anterior-posterior ratio we found no significant difference between Pompe patients and controls. Conclusion: MRI has good possibilities to evaluate simultaneously diaphragmatic and chest wall movements, which both contribute to pulmonary function. Cranial-caudal ratio and lung area ratio are decreased in the group of patients with Pompe disease compared to controls. We are currently exploring more specific diaphragmatic measures to see whether these can serve as a biomarker for diaphragmatic function in the evaluation of disease progression and response to therapy.

PS1Group1-041 / #478A CASE OF VLCAD DEFICIENCY MYOPATHY WITH NEW MUTATION AND FAVORABLE RESPONSE TO L-CARNITINE, RIBOFLAVIN, AND COQ10

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Farzad Fatehi¹, Yalda Nilipour², Shahriar Nafissi¹

¹Neurology, Tehran Univeristy of Medical Sciences, Tehran, IR;²Pathology, Mofid Hospital, Tehran, IR

Background: Very long-chain acyl-CoA dehydrogenase (VLCAD) deficiency is a very rare condition preventing the body from transforming very long-chain fatty acids (VLCAs) to energy, principally during periods of fasting. Signs and symptoms of VLCAD deficiency classically manifest during infancy or early childhood with hypoglycemia, lethargy, muscle weakness, and episodes of dark urine. There is no approved treatment for such patients. Herein, we describe a patient with a new mutation favorably responding to the treatment. Methods: A 38-year-old man was referred for a very slowly progressive lower limb weakness since childhood with the inability to climb upstairs since two years before. He reported episodes of dark urine after exercise. On examination, he had the weakness of neck flexion, bilateral arms abduction (MRC grade 3), bilateral elbows flexion (MRC grade 4), bilateral hips flexion (MRC grade 4), and bilateral knees extension (MRC grade 4) with normal deep tendon reflexes. The CK was 5400 IU/L; cardiac exams were normal; and electromyography demonstrated a myopathic pattern in proximal muscles of upper and lower limbs. Muscle MRI revealed moderate fat deposition in paraspinal muscles, adductor and vastus muscles as well as medial heads of gastrocnemius muscles. On muscle biopsy, myopathic atrophy of mainly type I fibers with multiple necrotic/regenerative fibers and fine lipid droplets in muscle fibers in ORO stain was seen. For genetic testing, DNA was extracted from blood cells and targeted next generation sequencing (NGS) was performed for this individual. The variants located in coding regions of all the 42 genes in this NGS panel for Metabolic Myopathies were evaluated. The obtained result was confirmed with the help of direct DNA sequencing of the candidate variant in the proband. Results: Targeted next-generation sequencing revealed a pathogenic variant defined as c.900G>A (p.Met300Ile) in exon 10 of ACADVL gene due to VLCAD deficiency (MIM#201475) not described previously. Segregation analysis for the parents confirmed the heterozygote status of both father and mother (carrier status) for ACADVL gene. We started L-carnitine 2 grams daily, CoQ10 300 mg daily and riboflavin 300 mg daily with a favorable response, and after one month the patient was able to climb upstairs without aid. Conclusion: In sum, it seems that the cocktail of L-carnitine, CoQ10, and riboflavin may be an optimal option for this very rare form of lipid storage myopathy.

PS1Group1-042 / #713IMPAIRED INSULIN SIGNALLING IN SKELETAL MUSCLE OF MYOTONIC DYSTROPHY PATIENTS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Laura V. Renna¹, Francesca Bose’¹, Elisa Brigonzi², Giovanni Meola², Rosanna Cardani³

¹Laboratory Of Muscle Histopathology And Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese (MI), IT;²Department Of Biomedical Sciences For Health, University of Milan, San Donato Milanese (MI), IT;³Laboratory Of Muscle Histopathology And Molecular Biology, IRCCS-Policlinico San Donato, San Donato Milanese (MI), IT

Background: Myotonic dystrophy type 1 (DM1) and type 2 (DM2) are neuromuscular multisystemic disorders caused by expanded CTG or CCTG repeats which lead to nuclear accumulation of mutant transcripts deregulating the activity of some splicing regulators and leading to aberrant alternative splicing of different genes. DM are characterized by metabolic dysfunctions such as insulin resistance, hyperinsulinemia and a fourfold higher risk of developing Diabetes mellitus type 2 (T2DM). Since it is known that insulin resistance is a risk factor for cardiovascular disease, neuropathy and loss of muscle mass, metabolic changes in DM patients might contribute to worsen some aspects of the disease at heart, skeletal muscle and brain level. Splicing alteration of insulin receptor (IR) gene is considered one of the causes of insulin resistance in DM patients, however it cannot be excluded that post-receptor signalling abnormalities could also contribute to this feature. The aim of this study is to investigate whether post-receptor abnormalities contribute to the peripheral insulin resistance in DM patients and whether deregulated metabolism pathways may be involved in muscle alterations, thus contributing to muscle atrophy and weakness in DM patients. Methods: Insulin pathway activation has been investigated in insulin stimulated skeletal muscle biopsies obtained from 9 DM1, 2 DM2, 5 healthy subjects (CTR) and 1 T2DM patients (ex vivo analysis). Activation of IRS1, AKT, p70S6K, GSK3ß, ERK1/2 and AMPK have been analysed by western blot. ERK1/2 involvement in DM insulin resistance has been investigated in human myotubes treated with the MEK inhibitor U0126 (25 μM). Results: Our results indicate that DM skeletal muscle exhibits high basal phosphorylation of AKT, GSK3ß and ERK1/2. Moreover, ex vivo analysis of insulin pathway activation has shown that insulin action appears to be impaired in DM samples as compared to CTR. Glucose uptake performed in human myotubes in the absence or presence of U0126 has shown that the specific decrease of ERK activity can lead to an increase in insulin dependent glucose uptake in both DM1 and DM2 muscle cells. Conclusion: In conclusion, ex vivo and in vitro studies show an alteration in activation of several proteins of insulin pathway that might contribute to DM insulin resistance. Results on the correlation between metabolic dysfunction and skeletal muscle impairment will be presented at the meeting. The results of this study may contribute to the identification of novel biomarkers that could be target for therapeutic intervention on insulin resistance and thus to improve the quality of life of DM patients.

PS1Group1-043 / #843DISTAL MYOPATHIES WITH RIMMED VACUOLE IN IRAN, A CLINICAL, HISTOPATHOLOGICAL AND GENETIC REPORT OF A LARGE GROUP

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Yalda Nilipour¹, Shahriar Nafissi², Farzad Fatehi³, Yalda Ashoorian⁴, Nahid Beladi Moghadam⁵, Reza Boostani⁶, Mohammad Rohani⁷, Bahram Haghi Ashtiani⁸, Babak Zamani⁹, Keyvan Basiri¹⁰, Fereshteh Ashtari¹¹, Davood Fathi³, Hosein Shamshiri²

¹Pathology, Pediatric Pathology Research Center, Research Institute for Children Health, Shahid Beheshti University of Medical Sciences, Tehran, IR;²Neurology, Tehran Univeristy of Medical Sciences, Tehran, IR;³Neurology, Iranian center of neurological research, Neuroscience institute, Shariati Hospital, Tehran Univeristy of Medical Sciences, Tehran, IR;⁴Pathology, Shahid Beheshti university of medical sciences, Tehran, IR;⁵Neurology, Shahid Beheshti university of medical sciences, Tehran, IR;⁶Neurology, Mashhad University of medical sciences, Mashhad, IR;⁷Neurology, Hazrat Rasool Hospital, Iran university of medical sciences, Tehran, IR;⁸Neurology, Firoozgar hospital, Iran university of medical sciences, Tehran, IR;⁹Iran University of Medical Sciences, Tehran, IR;¹⁰Isfahan University of Medical sciences, Isfahan, IR;¹¹Neurology, Isfahan University of Medical sciences, Isfahan, IR

Background: Distal myopathies are a rare group of neuromuscular disorders. Rimmed vacuoles are a feature of several myopathies, most of them predominantly affects the distal muscles. The presence of vacuoles in muscle biopsy associated with other pathological findings and the clinical phenotype of patients, age of onset, mode of inheritance and muscle imaging are important diagnostic clues. Rimmed vacuole myopathy is the most common type of distal myopathy in Iran and the highest prevalence of GNE myopathy was reported in Persians Jewish population. Methods: In this study, we retrospectively evaluate the clinical and histopathological characteristics of 75 Iranian patients (34 male and 41 female) from 75 different families with clinical suspicion of hereditary inclusion body myopathy, reported to have rimmed vacuoles in their muscle biopsies. We managed to perform direct sequencing for coding exons 1 to 12 of the GNE gene of 23 patients of this group. Results: Seventeen patients out of 75 had positive family history of muscle weakness. Age of onset of symptoms was 13 to 52 years. Nine patients did not show quadriceps sparing phenotype and 4 patients had loss of ambulation at the time of biopsy which was happened 4 to 13.5 years after onset of their symptoms. Maximum Creatine Kinase detected level was 3061 U/I. In microscopic evaluation, group atrophy was a common finding and some foci of chronic inflammation were identified in 12 cases. The number and the shape of the rimmed vacuoles was observed to be in a wide variety. Thirty-two cases showed necrotic fibers in their muscle biopsies and no congophilic inclusion was seen in 35 cases. Endomysial fibrosis and adipose tissue replacement were identified in 51 and 32 cases respectively. Intermyofibrillar network disruption as core-like lesions and moth-eaten fibers were seen in 41 cases and lobulated fibers were observed in ten muscle samples. Fiber type grouping was noted in 16 patients. No pathogenic mutation in GNE gene was found in 4 patients. Twelve patients were found to be homozygote for pathogenic mutations among which the most common one was c.2228T>C p.(Met743Thr) mutation in exon 12 observed in 8 cases and two of them had homozygote mutations in exon 4 followed by 1 in exon 3 and 1 in exon 9. One case found to be heterozygote for the GNE c.2228T>C pathogenic mutation. Four patients found to be heterozygote for one pathogenic mutation and one variant of uncertain clinical significance in different exons and 2 patients found to be putative homozygotes for same variant in exon 4 which was of unknown clinical significance. Conclusion: This study is the largest group study of 75 patients suffering from distal myopathy with rimmed vacuoles from Iran. Our findings emphasize the clinical, pathological and genetic heterogeneity of the disease. GNE myopathy is the most common early adult onset autosomal recessive distal myopathy in Iran. More extensive genetic studies such as whole exome sequencing on a larger group of patients may find new genes and will expand our knowledge.

PS1Group1-044 / #896GMPPB HOMOZYGOUS VARIANT IN ADULT ONSET LIMB GIRDLE MYASTHENIC SYNDROME: A LIKELY FOUNDER MUTATION

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Veeramani Preethish-Kumar¹, Ana Töpf², Kiran Polavarapu³, Aditi Joshi⁴, Sunitha Balaraju², Andreas Roos², Rita Horvath², Saraswati Nashi⁵, Seena Vengalil⁶, Aradhna Mathur⁴, Sushmita Nayak⁴, Sakshi Ambawat⁴, Mohammed Faruq⁴, Atchayaram Nalini⁶, Hanns Lochmüller⁷

¹Clinical Neurosciences, Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bengaluru, IN;²John Walton Muscular Dystrophy Research Center, Newcastle University, Newcastle, GB;³Clinical Neurosciences, Neurology, National Institute of Mental health and Neurosciences (NIMHANS), Bengaluru, IN;⁴Institute of Genomics and Integrative Biology, New Delhi, IN;⁵Neurology, National Institute of Mental Health and Neurosciences (NIMHANS), Bangalore, IN;⁶Neurology, National Institute of Mental Health and Neurosciences, Bengaluru, IN;⁷Department Of Neuropediatrics And Muscle Disorders, Freiburg University - Medical Center, Faculty of Medicine, Freiburg, DE

Background: Mutations in GMPPB encoding GDP-mannose pyrophosphorylase B affects glycosylation of a-dystroglycan resulting in Congenital muscular dystrophies (CMD) and Limb girdle muscular dystrophies (LGMD). To date there are few genetically verified individuals with GMPPB-associated dystroglycanopathiess. Recently, variants in GMPPB were reported to cause congenital myasthenic syndrome. Methods: Ten patients belonging to 4 south Indian families with late onset limb girdle syndrome and easy fatigability are described. Evaluation included clinical phenotyping, serum Creatine Kinase (CK), Repetitive nerve stimulation, and muscle biopsy. Six patients underwent genetic testing. Results: All were born to consanguineous parents. Five patients were evaluated at hospital and all had gradually progressive fatigable limb girdle weakness, prominent truncal weakness with calf hypertrophy and retained tendon reflexes (Table 1). CK levels were elevated in all (650 – 4547 IU/L). Muscle biopsy in 4 patients was suggestive of muscular dystrophy. RNS showed decrement response in probands from family 3 and 4. Pyridostigmine and Salbutamol were started in family 4, and they showed significant improvement in fatigue and weakness. Genetic analysis revealed identical missense mutation c.1000G>A (p.Asp334Asn) in exon 9 of GMPPB gene in 6 patients tested of all four families. This mutation was previously reported in a compound heterozygous form in two patients of Asian origin (Pakistan and India) in published literature. However, the phenotype described in these two cases was Congenital muscular dystrophy with CNS involvement. While, in all our patients the mutation was present in homozygous form and had a milder, slowly progressive phenotype consistent with Limb girdle myasthenic syndrome. This indicates the milder effect of the mutation which may require a different mutation to cause severe phenotype. As of now this variant has not been reported from other geographical regions. Furthermore, the allele frequency of c.1000G>A among south Asian population is 0.0005 and has zero frequency in other populations in ExAC database. Hence, we suspect a possible founder affect for this mutation in South Asia and needs to be further explored. Table 1: Clinical features. Conclusion: This report further expands the emerging phenotypic spectrum of GMPPB associated dystroglycanopathies and indicates a probable South Asian founder mutation with milder effect in its homozygous form.

PS1Group1-045 / #480NFAT5 AND P38 MAPKS INTERACT IN MUSCLE CELLS RESPONDING TO OSMOTIC AND INFLAMMATORY STRESS AND IN POLYMYOSITIS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Boel De Paepe¹, Sandrine Herbelet², Jens Schmidt³, Jan De Bleecker⁴

¹Neuromuscular Reference Center, Ghent University Hospital, Ghent, BE;²Ghent University, Ghent, BE;³Neurology, University of Goettingen, Goettingen, DE;⁴Neurology, Ghent University, Ghent, BE

Background: The transcription factor Nuclear Factor of Activated T-cells 5 (NFAT5) is the key regulator of cells’ responses to osmotic stress, but is also implicated in inflammatory muscle disease. NFAT5 most likely is regulated by Mitogen-activated protein kinases (MAPKs) and the four members of the p38 family of MAPKs, termed MAPK11 (p38ß), MAPK12 (p38γ), MAPK13 (p38δ) and MAPK14 (p38α), have known associations with inflammation. Methods: We study MAPKs mRNA expression and protein activation in an in vitro muscle inflammation model, and in muscle from polymyositis patients. Results: We observe that in muscle cells in culture, exposure to increased salt concentrations and ­pro-inflammatory cytokines influence NFAT5 mRNA expression and translocation to the nucleus. A maximal 4-fold increase of NFAT5 messenger levels in myotubes treated with IL1ß and IFNγ+IL1ß for 24h is detected, in the latter condition accompanied by a moderate increase of MAPK12 and MAPK13 phosphorylation. Neither MAPK14 expression nor phosphorylation is substantially altered by cytokines and increased NaCl concentrations. Longer exposure of myotubes in culture to cytokines does not increase NFAT5 nor MAPK14 expression, yet hyperosmotic conditions lead to a time-dependent increase of expression, reaching 9-fold (NFAT5) and 18-fold (MAPK14) after 72h. At this stage, culture densities decrease substantially, disfavoring the differentiated multinucleated cells and leaving myoblasts as the remaining cell developmental stage. In muscle tissues, levels of phosphorylated MAPK11/12/14 relative to actin content, increase from 0.52±0.24 in normal (n=4), to 0.87±0.23 in polymyositis (n=4), but this difference does not reach statistical significance (p=0.08). Immunofluorescent localization studies show expression in blood vessel endothelium and in a subset of small, most often CD56+ (regenerating) muscle fibers. Conclusion: We identify p38 MAPKs as possible phospho-activators of NFAT5 in muscle cell’s responding to inflammatory stress, and put forward MAPK12 as a likely regulator relevant to inflammatory myopathy.

PS1Group1-046 / #551IMPLICATION OF THE BREAKPOINTS POSITION IN PATIENTS WITH THE MACRODELETION OF EXONS 45 TO 55

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Javier Poyatos Garcia¹, Clara Gomis Coloma², Nuria Muelas³, Pilar Martí⁴, Juan J. Vílchez⁴

¹Neurology, Instituto de Investigación Sanitaria la Fe, Valencia, ES;²Neurology, INSTITUTO DE INVESTIGACIÓN SANITARIA LA FE, Valencia, ES;³Neurology, Hospital Universitari i Politècnic La Fe, Valencia, ES;⁴Neurology, Hospital Universitari i Politècnic La Fe, Universitat de València and CIBERER, Valencia, ES

Background: Duchenne muscular dystrophy (DMD) is a severe myopathy that affects to 1 out of 3500 -5000 newborn boys and it is responsible of severe disability and early death, caused by mutations in the DMD gene. Becker muscular dystrophy, is an allelic form, which manifest a benign phenotype. Sixty five per cent of the mutations in the DMD consist on intragenic deletions that disrupt the reading frame of the gene, while in BMD the reading frame is preserved. An emerging gene therapy in DMD patients consist on inducing skipping of an exon that recover the reading frame in a restrictive group of cases. Multiexon skipping is another approach that can be achieved with the new Crispr-Cas9 technology. In particular, 63% of DMD mutations are located between exons 45 to 55 and it has been observed the existence of a spontaneous deletion spanning that region in asymptomatic subjects or variable Becker phenotype. Our aim is to analyze the diverse clinical profile and to refine the underlying molecular mechanisms in a cohort of subjects with a 45-55 deletion. Our hypothesis is that the different location of the intronic breakpoint positions of these patients might be responsible of their clinical phenotype. Methods: We analyzed the exact position of the intronic breakpoints in 8 index patients with this deletion. We performed an array, and multiple PCRs in order to restrict the area of the breaking points in the introns 44-45 and 55-56, following by amplification and sequencing of the deletion junction to detect the exact breakpoint We also checked the clinical features of the patients in an attempt to correlate them with their sequences. Results: A group of 6 patients shared the same breakpoints in both introns. These patients presented variable clinical manifestation (2 asymptomatics, 2 mild BMD, 1 BMD and 1 with cardiomyopathy). In one of the other 2 patients, the deletion affected the regulatory regions of the dystrophin isoform Dp140 and in fact the patient presented ADHD (attention deficit hyperactivity disorder), dyslexia and dysgraphia. The last patient presented a proximal insertion of a stretch from a deleted region in the 44-45 intronic breakpoint. This patient showed an early onset cardiomyopathy. Conclusion: We cannot certainly affirm that t the position of the intronic breakpoints in patients with deletion 45-55 is related with the clinical features of these patients, nevertheless we found some associations. We detected a major hotspot, where 6 of 8 patients share the same breakpoints and present variable clinical manifestations, where we can find asymptomatic patients (suggesting that there are other factors that may have a greater impact on the clinical manifestation of the disease, such as age or genetic context). The impairment of the regulatory regions of Dp140 in our patient has a consequence in his cognitive status. Moreover the other type of deletion may be associated with an early apparition of cardiomyopathy, nevertheless more patients with the last 2 deletion categories must be analyzed in order to stablish these hypothesis.

PS1Group1-047 / #627THE STUDY OF ALISKIREN IN MDX DYSTROPHIC MICE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Thainá A. Marin¹, Bruno M. Bertassoli¹, Giuliana Petri¹, Jose F.R. Santos¹, Vinicius G. Silva², Fernando L.A. Fonseca³, Alzira A.S. Carvalho⁴, David Feder¹

¹Pharmacology, Faculdade de Medicina do ABC, Santo Andre, BR;²Faculdade de Medicina do ABC, Santo Andre, BR;³Laboratory Analysis, Faculdade de Medicina do ABC, Santo Andre, BR;⁴Neurology, Faculdade de Medicina do ABC, Santo Andre, BR

Background: Duchenne Muscular Dystrophy (DMD) is a genetic neuromuscular disease linked to the X chromosome, caused by mutation of dystrophin gene (DYS) that encodes the dystrophin protein, responsible for the stability of the sarcolemma. In the absence / deficiency of dystrophin, the muscle cells are susceptible to damage induced by continuous cycles of degeneration and limited regeneration. Inflammation, necrosis and fibrosis are the pathophysiological characteristics that lead to the main consequence of DMD, the loss of muscle function. Aliskiren is one of the newer drugs that interact with the Renin Angiotensin Aldosterone System (RAAS), directly inhibiting renin. High levels of circulating renin activate the pathologic signaling pathway of fibrosis in several diseases through stimulation of the pro-renin receptor, whose mechanism is completely independent of both Angiotensin II (ang II) production and stimulation of Ang II type 1 receptor. Methods: We treated 8-weeks-old male mdx mice. 8 mice received 25 mg / kg of Aliskiren daily for 5 weeks and 8 mice received 0,2ml of saline solution(0,9%), both by gavage. Measure muscle strength (Kondziela test) was performed weekly, as well as the weighing of each animal. After 5 weeks, all animals were euthanized, followed by muscles biopsy of extensor digitorum longus (EDL), tibialis anterior (TA) and diaphragm muscles in order to analyse morphological features. The creatine kinase (CK) was also performed. Results: No changes were observed in the animals weight during the study. The hold impulse calculated by the Kondziela Test did not show significant differences between treated and untreated animals. CK values between the groups did not differ significantly. Regarding the Feret’s diameter, a significant increase of fibers’diameter higher than 40um was observed in diaphragm muscle of treated group (p <0.05). In addition, TA of treated group showed a significant increase in fibers” diameter higher than 60um (p <0.05) was also demonstrated. In contrast, EDL did not show difference in fiber diameter of both groups. Conclusion: Treatment with aliskiren in mdx dystrophic mice for 5 weeks did not change the weight of animals. The strength was also unaffected in treated group. The preliminary analyzes of the morphological muscles findings not show some beneficial effect of aliskiren in this model. Long-term drug studies already under way, and measure of fibrosis and inflammatory cytokines will be very helpful to determine the real effect of aliskiren in DMD.

PS1Group1-048 / #691DUCHENNE MUSCULAR DYSTROPHY: DO BOYS WITH A SHORTER STATURE MAINTAIN AMBULATION LONGER?

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Léa Labove¹, Magdalena Jaworski¹, Cam-Tu Emilie Nguyen²

¹CHU Sainte-Justine, Montreal, QC, CA;²Pediatric Neurology, CHU Sainte-Justine, Montreal, QC, CA

Background: Duchenne muscular dystrophy (DMD) is an X-linked progressive neuromuscular disorder caused by mutations in the DMD gene and affecting approximately 1:5000 male births, leading to loss of ambulation and premature death. While many promising therapies are currently being developed, corticosteroids remain the cornerstone of pharmacological management in DMD. Stunted growth is a frequent side effect of steroids in DMD patients. It is not uncommon for families and patients to voice concerns about this “visible” side effect of corticotherapy. Some clinicians have ventured that a shorter stature may confer a mechanical advantage in DMD, delaying the loss of ambulation in the shorter boys. Methods: Our aim was to study the relationship between height and the age at loss of ambulation in our population of DMD boys through a single-center retrospective chart review. Seventy boys with DMD were identified and their charts reviewed. The median age at diagnosis was 4.2 years, and median age of corticosteroid initiation was 7.5 years. Out of these 70 boys, 40 had lost ambulation at the time of this study, at a mean age of 11.6 years. We separated the boys who had lost ambulation in two groups: those who lost ambulation before 11.6 years and those who lost ambulation after 11.6 years, and compared these two groups in terms of height, using the Student’s T-test. Results: At age 10, the boys who lost ambulation after 11.6 years were on average 11.9 cm shorter than the boys who lost ambulation before 11.6 years (p<0.0001), a difference that is both statistically and clinically significant. When we looked at the height at age 7 instead of 10, the difference between the two groups was not statistically significant (+1.5 cm for the boys who lost ambulation before 11.6 years; p=0.3731). Given that the difference in average height between the two groups appears to develop between the ages of 7 and 10, we hypothesize that the height differential is due to the effect of corticosteroids, which were initiated at a median age of 7.5 years. Conclusion: In our cohort, DMD boys who lost ambulation at a later age were significantly shorter than those who lost ambulation earlier. It is not yet clear if this is due to a mechanical advantage related to the shorter stature, or if the shorter stature could represent a biomarker of optimal corticotherapy response in DMD. This important finding should be validated in multicentric DMD cohorts.

PS1Group1-049 / #898LOW LEVELS OF DYSTROPHIN PROTEIN ASSOCIATED WITH ATTENUATION OF DUCHENNE MUSCULAR DYSTROPHY PROGRESSION

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Johannes Dworzak¹, Frederick Schnell², Jay S. Charleston¹, Karin Lucas², Doug Sanders¹, Diane Frank²

¹Sarepta Therapeutics, Inc., Cambridge, MA, US;²Sarepta Therapeutics Inc, Cambridge, MA, US

Background: Duchenne muscular dystrophy (DMD) is a degenerative, fatal, X-linked recessive disorder affecting 1 in 3500 to 5000 male births worldwide. It is marked by an absence of dystrophin in muscle fibers stemming from DMD gene mutations. Absence of dystrophin leads to progressive loss of muscle function. The precise amount of dystrophin associated with clinically meaningful benefit in DMD patients is unclear, although numerous findings indicate that small amounts of dystrophin, associated with natural mechanisms such as spontaneous exon skipping, may lead to slower disease progression. We explored potential associations between low dystrophin levels in DMD patients and attenuation of disease progression. Methods: A literature search was conducted to identify recent relevant articles evaluating the natural occurrence of exon skipping and clinical disease progression in DMD patients. Results: A body of evidence indicates that DMD patients with mutations amenable to exon 44 skipping experience a milder disease course than other DMD subgroups. In one natural history study, patients with mutations amenable to exon 44 skipping experienced a slower rate of disease progression, with loss of ambulation (LOA) 2 years later than those with other mutations, yet traces of dystrophin were detected in only 3 of 6 patients by immunohistochemistry and in 0 of 4 patients by Western blot analysis using clinical diagnostic methods. Notably, in a subanalysis of corticosteroid-treated patients, those with mutations amenable to exon 44 skipping did not achieve a median age of LOA during follow-up, while those with mutations amenable to exon 51 skipping had a median age at LOA of 13.0 years. In a separate analysis of corticosteroid-treated DMD patients, the median age at LOA was 15.2 years in patients amenable to exon 44 skipping and 10.5 years in patients amenable to exon 51 skipping. Spontaneous low-level exon 44 skipping in these patients is thought to facilitate restoration of the messenger ribonucleic acid reading frame, facilitating dystrophin expression and/or the presence of dystrophin-positive muscle fibers. An analysis utilizing the NorthStar Ambulatory Assessment demonstrated that patients with mutations amenable to exon 44 skipping declined less rapidly over 2 years than patients with mutations amenable to exon 53 or 51 skipping. A separate study showed that patients with mutations amenable to exon 44 skipping had higher baseline values on the 6-minute walk test and more modest declines at 12 months than those with mutations amenable to skipping exons 45 or 53 (differences were not statistically significant). Some evidence suggests that DMD patients with deletions of exons 3–7 also experience a milder phenotype and express low levels of dystrophin. A recent case study described a patient aged 10 years with a nonsense mutation in exon 42 and a mild phenotype that was presumably the result of spontaneous exon 42 skipping and subsequent dystrophin production. Conclusion: These findings demonstrate that spontaneous exon skipping and production of low dystrophin levels may impact the clinical course of the disease, and offer insights regarding the interpretation of results from clinical trials evaluating therapeutic interventions designed to restore dystrophin in DMD patients.

PS1Group1-050 / #934TAMOXIFEN PROLONGS SURVIVAL, IMPROVES MOTOR FUNCTION AND REDUCES LEVELS OF DNM2 IN MTM1-NULL MICE, A MODEL OF XLCNM

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Elinam Gayi¹, Laurence A. Neff¹, Hesham M. Ismail¹, Xènia Massana-Muñoz², Belinda S. Cowling², Jocelyn F. Laporte², Leonardo Scapozza¹, Olivier M. Dorchies¹

¹School Of Pharmaceutical Sciences, University of Geneva, Geneva, CH;²Department Of Translational Medicine And Neurogenetics, University of Strasbourg, Illkirch, FR

Background: X-linked centronuclear myopathy (XLCNM) is a rare and severe congenital myopathy characterised by generalised muscle weakness and abnormal nuclei positioning. Most affected boys die in their first year of life and survivors fail to achieve independent ambulation. It is caused by mutations in the Mtm1 gene encoding myotubularin, a ubiquitously expressed phosphoinositide phosphatase. No cure exists and very few pharmacological avenues are being explored. Here, Mtm1-null mice were treated with tamoxifen (TAM), a drug that modulates oestrogen actions and that we have previously shown to be efficacious in dystrophic (mdx^5Cv) mice, a model of Duchenne muscular dystrophy (DMD). We report that TAM is also effective in Mtm1-null mice, a model of XLCNM. Methods: Wild type and Mtm1-null mice were given normal chow or a TAM supplemented chow starting at weaning. Survival was monitored, and mice underwent weekly grid-tests, weigh-ins and clinical scorings to evaluate disease progression. Mice were kept until Day 42, 84 or >200; at each of these time points in-vivo force recordings were performed in the triceps. Hind leg muscles were used for histological, ultrastructural and biochemical analyses. Results: Non-treated Mtm1-null mice died at around 45 days. By contrast, about half of the Mtm1-null mice treated with clinically relevant doses of TAM survived beyond 290 days of age. Clinical scoring showed that the motor function of the affected mice was markedly improved. In vivo force recordings performed at D42 and D84 revealed that the force of treated Mtm1-null was significantly improved after as short as 3 weeks of treatment. Histological and electron microscopy analyses show partial rescue of muscle structure and triads, consistent with improved calcium homeostasis in FDB fibres and better excitation-contraction coupling. Quantitative PCR and western blots demonstrated reduction of DNM2, a disease modifier in XLCNM. Conclusion: We found that tamoxifen extends the lifespan of Mtm1-null mice more than 6-fold, rescues their motor skills and corrects levels of known disease modifiers. These results suggest that oestrogen signalling may be a key pathway that modifies disease severity in unrelated myopathies such as XLCNM and DMD.

PS1Group1-051 / #961ARE THERE DIFFERENT CLINICAL ENTITIES WITH DISTINCT DISEASE COURSE AMONG D4Z4 REDUCED ALLELE CARRIERS?

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Giulia Ricci¹, Fabiano Mele², Lucia Ruggiero³, Elisabetta Bucci⁴, Lorenzo Maggi⁵, Monica Govi², Francesco Sera⁶, Liliana Vercelli⁷, Lucio Santoro³, Tiziana Mongini⁷, Luisa Villa⁸, Maurizio Moggio⁸, Massimiliano Filosto⁹, Marina Scarlato¹⁰, Stefano C. Previtali¹⁰, Michelangelo Cao¹¹, Elena Pegoraro¹², Roberta Telese¹³, Antonio Di Muzio¹³, Carmelo Rodolico¹⁴, Giovanni Antonini⁴, Maria Grazia D’Angelo¹⁵, Angela Berardinelli¹⁶, Rachele Piras¹⁷, Maria Antonietta Maioli¹⁷, Giuliano Tomelleri², Corrado Angelini¹⁸, Gabriele Siciliano¹, Rossella Tupler²

¹Department Of Clinical And Experimental Medicine, University of Pisa, Pisa, IT;²Department Of Life Sciences, University of Modena and Reggio Emilia, Modena, IT;³Department Of Neurosciences, Reproductive And Odontostomatological Sciences, University Federico II of Naples, Naples, IT;⁴Department Of Neuroscience, Mental Health And Sensory Organs, S. Andrea Hospital, University of Rome “Sapienza”, Rome, IT;⁵Besta Neurological Institute, Milan, IT;⁶Mrc Centre Epidemiology For Child Health, UCL Institute of Child Health, London, GB;⁷Department Of Neuroscience, Center For Neuromuscular Diseases, University of Turin, Turin, IT;⁸Fondazione Irccs Ca’ Granda Ospedale Maggiore Policlinico, Dino Ferrari Center, University of Milan, Milan, IT;⁹Neurology Clinic, Spedali Civili Hospital, University of Brescia, Brescia, IT;¹⁰Inspe And Division Of Neuroscience, IRCCS San Raffaele Scientific Institute, Milan, IT;¹¹Department Of Neurosciences, University of Padova, Padova, IT;¹²University of Padova - Azienda Ospedaliera di Padova, Padova, IT;¹³Center For Neuromuscular Disease, Cesi, University “G. D’Annunzio”, Chieti, IT;¹⁴Department Of Neurosciences, Policlinico “g. Martino”,, University of Messina, Messina, IT;¹⁵Department Of Neurorehabilitation, IRCCS Institute Eugenio Medea, Bosisio Parini, Bosisio Parini, IT;¹⁶Unit Of Child Neurology And Psychiatry, IRCCS“C. Mondino” Foundation, Pavia, Pavia, IT;¹⁷ASL8, Centro Sclerosi Multipla, Cagliari, IT;¹⁸IRCCS S.Camillo Hospital, Venice, IT

Background: The phenotypic classification of patients with facioscapolohumeral muscular dystrophy (FSHD) is crucial for genetic studies and the definition of outcome measures toward trial readiness. The Italian Clinical Network for FSHD has recently proposed a new FSHD Comprehensive Clinical Evaluation Form (CCEF) that defines nine clinical categories aimed at capturing clinical diversity. In particular category A, subcategories A1-A3, identifies subjects with facial and scapular girdle weakness, subcategory B1 identifies patients showing scapular muscle weakness without facial muscle involvement. Methods: We applied the CCEF on 814 index cases carrying of contracted alleles with 1-10 D4Z4 repeats from the Italian National Registry for FSHD. Results: Our analysis suggests that the facial-sparing FSHD phenotype (subcategory B1), representing 10,2% of index cases, is associated with milder motor disability and slower progression of muscle weakness when compared with the classical FSHD phenotype (category A), regardless the size of the D4Z4 contracted allele. Conclusion: These results highlight the importance of building a precise phenotypic classification of patients and families for a correct stratification of patients to identify the best for trials.

PS1Group1-052 / #285A PH1/2 STUDY OF ENA^® ANTISENSE OLIGONUCLEOTIDE (DS-5141B) WITH EXON 45 SKIPPING ACTIVITY IN PATIENTS WITH DMD

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Masafumi Matsuo¹, Hiroyuki Awano², Setsuo Hasegawa³, Satoru Inoue⁴, Naoyuki Maeda⁴, Hirofumi Komaki⁵

¹Department Of Physical Therapy, Faculty Of Rehabilitation, Kobe Gakuin University, Kobe, JP;²Pediatrics, Kobe University Graduate School of Medicine, Kobe, JP;³Pharmaspur Inc., Tokyo, JP;⁴Daiichi Sankyo Co., Ltd., Tokyo, JP;⁵Child Neurology, National Center of Neurology and Psychiatry, Tokyo, JP

Background: Duchenne muscular dystrophy (DMD) is a progressive, lethal neuromuscular disorder caused by the absence of dystrophin due to mutation of the DMD gene. Antisense oligonucleotide (AO)-mediated exon skipping allows restoration of the dystrophin reading frame, resulting in the synthesis of partially functional dystrophin for DMD patients who have out-of-frame deletions. This exon skipping treatment strategy for DMD is now being studied using various modified nucleic acids. The most important drawback of AOs that target DMD exon skipping is not delivered into cardiac muscle. DS-5141b is an AO consisting of 2’-O,4’-C-ethylene-bridged nucleic acids (ENA^®) and 2’-O-methyl RNA (2’-OMe) and induces DMD exon 45 skipping. Our ENA^® oligonucleotides have suitable characteristic for nucleic acid therapeutics. They can form more thermodynamically stable duplexes with complementary RNA than other oligonucleotides and are highly stable in plasma. In pre-clinical studies, the potent efficacy and safety of DS-5141b was observed. DS-5141b at doses over 3 mg/kg induced distinct exon 45 skipping in anterior tibial muscles, diaphragm and heart in mdx mice. On the other hand, 2’-OMe AO and a phosphorodiamidate morpholino oligomer (PMO) AO with the same nucleotide sequence as DS-5141b did not show the clear exon-skipping activity at doses up to 30 mg/kg. It was remarkable that the exon 45 skipping was detected in heart at such a low dose suggesting cardiac improvement (Neuromuscular Disorders Vol. 27 Suppl. 2, 2017, Page S216). Methods: To assess the safety, tolerability, efficacy, and pharmacokinetics of DS-5141b in patients with DMD, a phase 1/2 study has been conducted as a multicenter, uncontrolled, open-label study in Japan (NCT02667483). This study was a first-in-human study consisted of 2 parts. Part 1 was a sequential dose escalation part to examine 4 dose levels (0.1, 0.5, 2.0 and 6.0 mg/kg). DS-5141b was administered subcutaneously at 2 dose levels each in 2 cohorts and administration of each dose level was once weekly for 2 weeks (Cohort 1: 0.1 and 2.0 mg/kg, Cohort 2: 0.5 and 6.0 mg/kg). In Part 2, subcutaneous administration of DS-5141b was conducted for 12 weeks at 2 dose levels (2.0 and 6.0 mg/kg). Eligible subjects were ambulant DMD male patients aged 5-10 years with a mutation amenable to exon 45 skipping. Safety assessments include adverse event, laboratory tests, change of weight, vital sign, and ECG. The primary efficacy endpoint of this study is dystrophin expression and the secondary is detection of in-frame DMD mRNA harboring exon 45 skipping in muscle tissue. Results: A total of 7 subjects had received DS-5141b and all of them had completed administration for 12 weeks in Part 2. No serious adverse events and adverse events resulting in discontinued administration have been reported. Conclusion: Results of the Ph1/2 study and properties of DS-5141b will be presented.

PS1Group1-053 / #517MOST LGMD2L MUTATIONS IN THE ANO5 GENE RESULT IN DECREASED PROTEIN LEVELS IN ANOCTAMINOPATHY PATIENTS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Anna Vihola¹, Helena Luque², Marco Savarese², Sini Penttilä³, Giorgio Tasca⁴, Bjarne Udd⁵

¹Medical Genetics, Medicum, Folkhalsan Institute of Genetics, Uni Helsinki, Helsinki, FI;²Medical Genetics, Medicum, Folkhalsan Institute of Genetics, Uni Helsinki, Helsinki, FI;³Neuromuscular Research Center, University and University Hospital of Tampere, Tampere, FI;⁴Fondazione Policlinico Universitario “a. Gemelli”, Istituto di Neurologia, Università Cattolica del Sacro Cuore, Rome, IT;⁵Department Of Neurology, Vaasa Central Hospital, Vaasa, FI

Background: ANO5 (TMEM16E) is an eight-pass, 107 kDa membrane protein, possibly playing a role in membrane dynamics. Mutations in the ANO5 gene are a frequent cause of recessive limb-girdle muscular dystrophy, LGMD2L, and Miyoshi muscular dystrophy -like disease MMD3, with distal phenotype. More than 70 different mutations, dispersed all over the ANO5 gene have been identified. The most frequent mutation in European populations is the truncating c.191dupA in the N-terminal domain of the ANO5 protein, whereas in Finland, the point mutation c.2272C>T is the most common. In addition, there are numerous patients with phenotypes compatible with anoctaminopathy, but with just one confirmed ANO5 mutation found in genetic analysis, leaving the diagnosis unsolved with conventional approach. Methods: Studying the effects of ANO5 mutations in patient biopsies at protein level for diagnostic purposes has become possible only recently, as we developed a novel western blotting method, using isolated membrane fractions, suitable for endogenous ANO5 detection in human muscle tissue. Anoctaminopathy patients in this study were confirmed by genetic analysis. Results: Using this technique, a commercial mouse monoclonal antibody detected a single 107 kDa ANO5 protein in normal muscle biopsy membrane fractions. The ANO5 band was clearly decreased in most anoctaminopathy patients tested, except for a patient with a very N-terminal point mutation, located in the soluble cytoplasmic domain of ANO5. Conclusion: We conclude that ANO5 has low tolerance for mutations, leading in most cases to protein destabilization and degradation. The method described here allows direct analysis of human ANO5 protein, which can be used in diagnostics, for evaluating the pathogenicity of the potentially harmful ANO5 variants of uncertain significance.

PS1Group1-054 / #628CRISPR/CAS GENE EDITING IN DUCHENNE MUSCULAR DYSTROPHY CULTURES TO TEST NEW TREATMENTS FOR THE DISEASE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Patricia Soblechero-Martin¹, Iker García-Jiménez², Estibaliz Ruiz-Del-Yerro², Edurne Albiasu-Arteta², Virginia Arechavala-Gomeza¹

¹Neuromuscular Disorders, Biocruces Health Research Institute, Barakaldo, ES;²Neuromuscular Disorders, Biocruces Health Research Institute, Barakaldo, ES

Background: Gene editing techniques have the possibility of becoming a permanent cure to many genetic disorders, but the delivery hurdle of these techniques will delay their practical application, particularly in neuromuscular disorders where muscle represents an extremely large and widespread target. However, these techniques have a more immediate application in the generation of better disease models in a field where not many good human myogenic cultures are available. Methods: The aim of our studies is to use gene editing to generate a specific DMD deletion in healthy control myoblasts cultures and then correct this deletion also by gene editing, the first objective will provide us with a model to test many possible mutation-specific treatments, such as antisense oligonucleotides, while the second is a proof of concept of a possible therapeutic gene editing option. Results: For our first objective, we have designed specific guide RNAs to edit the DMD gen removing exon 52 in order to reproduce a common deletion in Duchenne patients. We have confirmed the efficacy of our designs and selected the best candidates in HEK293 cells. Once selected, the best candidate gRNAs have been transfected in a control myoblast culture to create this new “DMD-like” culture. To complete our second objective, we have designed gRNAs targeting exon 51 and followed the same methods, this time on a DMD culture missing exon 52, to restore dystrophin expression. Conclusion: Issues such as safe and efficient delivery to target regions stop gene editing from being an immediate therapeutic option, but, as shown in this poster, gene editing is a useful tool to create better disease models to help in the development of other treatments and could be a feasible option to ex vivo treatment of cultures before autologous transplant.

PS1Group1-055 / #693EXTRA-SKELETAL MUSCLE MANIFESTATIONS OF FACIOSCAPULOHUMERAL MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Cecilia Kelly, Elie Naddaf

Mayo Clinic, Rochester, MN, US

Background: Facioscapulohumeral muscular dystrophy (FSHD) is the third most common cause of muscular dystrophy. It is inherited in an autosomal dominant pattern. Over 95% of FSHD cases are type 1, due to a contraction in the D4Z4 repeats on chromosome 4p. In its classic form, FSHD is characterized by weakness of facial and shoulder girdle muscles, and can be associated with hearing loss and rarely, retinal vascular abnormalities. However, the extra-skeletal muscle manifestations of FSHD remain poorly explored. In this study, we aimed to better characterize the spectrum of such manifestations in a large, single center cohort of FSHD patients. Methods: We performed a retrospective chart review of patients seen between 2000 and 2017 carrying the diagnosis of FSHD. We only included patients with genetically-confirmed FSHD type 1 or 2. We reviewed medical records for evidence of extra-skeletal muscle manifestations in the following domains: 1) hearing loss, captured by audiometry and/or hearing aid use; 2) cardiac disease, captured by electrocardiogram, Holter, and/or echocardiography; 3) dysphagia, captured by video swallow study; 4) retinopathy, captured by ophthalmologic exam; and 5) respiratory dysfunction, captured by pulmonary function tests (PFTs) and/or overnight oximetry. Results: We identified 88 patients, 39 of whom (44%) were female. At time of evaluation, median age was 44 years (range 1.5-89), and 69 patients (78%) were adults (>18 years old). Hearing loss was present in 10 of 15 (67%) tested patients, 8 of whom were diagnosed in adulthood. Ocular abnormalities were found in 5 of 25 (20%) patients; however, none were noted to have retinal telangiectasias or exudates. Electrocardiography was abnormal in 29 of 56 patients (52%) and echocardiography was abnormal in 18 of 35 tested patients (51%). Oropharyngeal dysphagia was documented in 8 of 17 (47%) patients who underwent video swallow study, most commonly classified as mild to moderate. PFTs were abnormal in 25 of 27 patients (93%): 8 had a restrictive pattern and 23 had reduced maximal respiratory pressures. Overnight oximetry showed sleep-related disordered breathing in 14 of 24 patients (58%). A single patient had focal epilepsy diagnosed in adulthood. We will analyze the correlation between the various extra-skeletal muscle manifestations and the number of D4Z4 repeats, and present it at the time of the conference. Conclusion: Hearing loss, cardiac abnormalities, dysphagia, and respiratory insufficiency were relatively common in our cohort. However, retinal vascular abnormalities were not encountered. Increased awareness regarding the various extra-skeletal muscle manifestations of FSHD allows timely screening, and subsequently providing better patient care.

PS1Group1-056 / #717ANALYSIS OF CARDIAC TROPONIN T ALTERNATIVE SPLICING IN SKELETAL MUSCLE OF DM1 PATIENTS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Francesca Bose’¹, Laura V. Renna¹, Nicola Ferrari², Valentina Labate³, Michele Cavalli⁴, Giovanni Meola⁵, Rosanna Cardani⁶

¹Laboratory Of Muscle Histopathology And Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese (MI), IT;²Department Of Biomedical Sciences For Health, University of Milan, Milan, IT;³Department Of Cardiology Heart Failure Unit, IRCCS Policlinico San Donato, San Donato Milanese (MI), IT;⁴Department Of Biomedical Sciences For Health, IRCCS Policlinico San Donato, Milan, IT;⁵Department Of Biomedical Sciences For Health, University of Milan, San Donato Milanese (MI), IT;⁶IRCCS-Policlinico San Donato, San Donato Milanese (MI), IT

Background: Myotonic dystrophy type 1 (DM1) is an autosomal dominant neuromuscular disorder caused by expanded CTG repeats in the DMPK gene. Nuclear accumulation of the mutant RNA leads to aberrant alternative splicing of different genes that have been linked to the multiorgan involvement that characterized the pathology. Alteration of cardiac Troponin T (cTnT) alternative splicing observed in DM1 patients leads to the co-expression of both adult (excluding-exon 5) and fetal (including-exon 5) isoform in cardiac tissue and it is considered one cause of cardiac dysfunctions in DM1. Recently, cTnT aberrant splicing pattern has been observed also in skeletal muscle of DM1 patients. The aim of this work is to study the cTnT alternative splicing in biceps brachii (BB) muscle biopsies and in tibialis anterior (TA) samples from DM1 patients and to investigate if it is related to cardiac dysfunctions observed in these patients. Methods: cTnT fetal isoform expression was evaluated by RT-PCR using primers flanking exon 5 on both BB (n=12) and TA samples (n=11) from DM1 patients and healthy subjects (CTR; n=6 BB, n=4 TA). Patients were divided in two main groups on the basis of cardiac evaluation performed by ECG, echocardiogram and 24h ECG-Holter. Patients with cardiac involvement present at least one out of four altered parameters (increased PR, QRS, QTc, reduced %FE). Results: Both in BB and TA samples, a significantly higher expression of cTnT fetal isoform was observed in DM1 patients presenting cardiac involvement than in CTR. Moreover, in TA samples a correlation between the expression of fetal cTnT with QTc and %FE was present. In order to verify if the alteration of cTnT splicing is related to skeletal muscle alterations, we analysed aberrant alternative splicing of muscle specific genes (CLCN1, CACNA1S, NFIX, SERCA1, TNNT3, DMD1, LDB3, RYR1 and BIN1) and histopathological parameters of muscle damage (atrophic and hypertrophic factor, % of fibers with central nuclei, % of MHC embrional and neonatal positive fibers) on both BB and TA muscle biopsies. No correlation was found between cTnT fetal isoform expression and the parameter of skeletal muscle impairment. Conclusion: In conclusion, fetal isoform expression both in BB and TA skeletal muscle of DM1 patients seems to be related to cardiac involvement and could represent a possible biomarker of heart dysfunction in these patients.

PS1Group1-057 / #784IMPACT OF IDEBENONE ON RESPIRATORY BURDEN, INCLUDING RISK OF BRONCHOPULMONARY COMPLICATIONS, IN DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Oscar H. Mayer¹, Mika Leinonen², Shabir Hasham³, Thomas Meier², Thomas Voit⁴, Gunnar Buyse For The Delos Study Group⁵

¹Children’s Hospital of Philadelphia, Philadelphia, PA, US;²Santhera Pharmaceuticals, Pratteln, CH;³Santhera Pharmaceuticals, Pratteln, CH;⁴UCL Great Ormond Street Institute of Child Health, London, GB;⁵University Hospitals Leuven, Leuven, BE

Background: In Duchenne muscular dystrophy (DMD), respiratory function declines due to progressive muscle weakness, and accelerates once patients become non-ambulatory. As well-described clinical thresholds are crossed (based on forced vital capacity, expressed as a percentage of the predicted value; FVC%p), the risk and severity of respiratory complications, including bronchopulmonary adverse events (BAEs),¹ increases, presenting an ever worsening disease burden. In the 52 week, Phase 3 clinical trial in DMD patients not taking glucocorticoids (DELOS), we examined the potential for idebenone to reduce the rate of respiratory function decline and the rate of BAEs. Methods: Using a combination of pre-specified and post-hoc analyses, we assessed data from the DELOS trial, which enrolled 64 DMD patients aged 10-18 years and already in respiratory decline (peak expiratory flow %p < 80%), to determine the potential of idebenone (900mg/day) to reduce disease burden by delaying the time to reaching clinically relevant respiratory function thresholds, and the frequency of BAEs. Clinically relevant thresholds for FVC%p, were compiled following a review of standard of care guidelines. We compared the number of patients (idebenone vs placebo) crossing these thresholds (FVC%p of 50%, 40%, 30%) or experiencing BAEs. Results: Treatment with idebenone reduced the risk of crossing the clinically relevant FVC%p threshold of 50% compared to placebo (hazard ratio = 0.34, (95% CI: 0.10 – 1.18). A similar trend was observed for patients crossing any clinically relevant FVC%p threshold (50, 40 or 30%) (hazard ratio = 0.51, 95% CI: 0.23 – 1.14). Patients in the idebenone group were also at a lower risk of experiencing a BAE than those in the placebo group (hazard ratio = 0.28, 95% CI: 0.12 – 0.64). Conclusion: In the DELOS trial, idebenone treatment significantly reduced the proportion of patients crossing any clinically relevant threshold of FVC and also reduced the risk of bronchopulmonary adverse respiratory events, further supporting the efficacy and utility of treatment with idebenone in patients with DMD in established respiratory function decline and not taking glucocorticoid therapy. 1. Mayer OH, et al. US Neurology 2017;13:35-41.

PS1Group1-058 / #811CLINICAL AND MOLECULAR FEATURES OF DISTAL MYOPATHIES IN A PORTUGUESE COHORT: REPORTING NOVEL GENE MUTATIONS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Catarina Falcão De Campos¹, Miguel Oliveira Santos¹, Isabel Conceição², Mamede De Carvalho²

¹1- Departamento de Neurociências e Saúde Mental, CHLN- Hospital Santa Maria. Lisboa, Portugal 2- Instituto de Fisiologia, Universidade de Lisboa, Faculdade de Medicina, IMM. Lisboa, Portugal, Lisbon, PT;²1- Departamento de Neurociências e Saúde Mental, CHLN- Hospital Santa Maria. Lisboa, Portugal 2- Instituto de Fisiologia, Universidade de Lisboa, Faculdade de Medicina, IMM. Lisboa, Portugal, Lisbon, PT

Background: Distal myopathies (DM) are a clinically and genetically heterogeneous group, which selectively or disproportionally affect distal muscles. DM are classified according to age of onset, inheritance pattern, clinical features and molecular diagnosis. Recent developments in identifying the underlying gene defects have increased the number of disorders, to more than 20 entities. Some forms of DM have higher prevalence in certain regions, such as Welander Myopathy in Sweden and Udd Myopathy in Finland. We describe the phenotypic and molecular features of the first cohort of Portuguese patients with DM, reporting novel gene associations. Methods: We retrospectively assessed patients with DM and molecular diagnosis followed in our center. Demographic and clinical data, familiar history, neurophysiological and pathological findings as well as gene mutations were collected. Results: We identified 123 patients with myopathy followed in our center which only 9 patients (7,3%) were classified as DM. Two thirds of the patients with DM had molecular genetic diagnosis, including four novel mutations. The demographic and clinical features are described in table 1. Three patients were diagnosed as tibial muscular dystrophy (Udd myopathy) associated with two likely pathogenic titin (TTN) gene mutations not previously described in the literature. Two patients were father and son and presented with the same TTN gene mutation. One young patient had diagnosis of Miyoshy myopathy, with a likely pathogenic novel mutation in the dysferlin gene. An older patient presented with progressive upper and lower limbs distal weakness. Five years later the patient developed cognitive deterioration suggestive of a frontotemporal dementia, without associations with Paget disease. A novel gene mutation in the valosin-contain-protein (VCP) was diagnosed. Lastly, we report a patient with lower limb distal weakness and hypertrophic cardiomyopathy associated with MYH7 gene mutation. Conclusion: We summarize the first cohort of Portuguese patients with DM associated with genetic mutations, including 4 novel mutations. To our knowledge, we describe for the first time a Portuguese patient with IBMPFD diagnosis associated with a novel VCP gene mutation. Molecular genetic investigation was essential since some of our patients are sporadic cases.

PS1Group1-059 / #965DUCHENNE MUSCULAR DYSTROPHY AND THE HEART - HOW TO VISUALIZE BETTER? CASE SERIES REPORT

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Ruza Kalicanin Milanovic¹, Ana Kosac², Stefan Djordjevic³, Maja Bjelic³, Milan Djukic³, Jelena Mladenovic², Jelena Glumac², Tamara Ristic², Majda Kiklic², Ida Jovanovic³, Vedrana Milic Rasic²

¹Health Centar Novi Pazar, Novi Pazar, RS;²Neurology, Clinic of neurology and psychiatry for children and youth, Belgrade, RS;³University children’s hospital, Belgrade, RS

Background: During the progressive course of disease of Duchenne muscular dystrophy monitoring of heart function and diagnosing the very first signs of potential heart failure is of vital importance. Aim: To correlate functional measures of patient achievements to different visualized procedures of the heart made at the same time period. Methods: We performed complete cardiological assessment, echocardiography, cardiac magnetic resonance imaging, biochemical parameters of patients diagnosed with Duchenne muscular dystrophy, confirmed by molecular genetic testing, in uniform fashion by three pediatric cardiologists educated in the same manner. All neurological assessment was performed by pediatric neurologists. Results: We included 16 boys with Duchenne muscular dystrophy, age range from 6 to 12 years (mean 9,2 +-1,7), from whom 87,5% were on stable doses of corticosteroid therapy and 81,2% were mobile, with six minute walk test in rage 182 to 579 m. Normal sinus rhythm (85-124/min) and cardiac auscultatory findings were found in all patients, with QTc interval from 0,36 to 0,43 seconds, slightly increased R/S in V1 in 9 (56,2%) patients and NT-proBNP from 7.69 to 231.6 pg/ml. In echocardiography parameters shortening fraction and ejection fraction were lower than 28% and 55% only in one patient (6,25%) 8 years old, independently mobile and on corticosteroid therapy. Cardiac magnetic resonance imaging revealed thin right ventricular myocardial wall and presence of left ventricular fibrosis in 25% of our patients, all mobile, on corticosteroid therapy and without echocardiography parameters of heart failure, with one patient having unexpectedly large fields of fibrosis despite excellent motor performances and normal echocardiography findings. Conclusion: Although echocardiography is a more available and easier accessible method, cardiac magnetic resonance imaging is becoming a superior diagnostic tool in the field of visualizing the first signs of potential cardiac dysfunction and failure in patients with Duchenne muscular dystrophy.

PS1Group1-060 / #753RATIONALE FOR EDASALONEXENT DOSE SCHEDULE IN PHASE 2 OF THE MOVEDMD® TRIAL

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Hanlan Liu¹, Richard S. Finkel², H.Lee Sweeney³, Krista Vandenborne⁴, Maria Mancini⁵, John F. Reilly⁶, Pradeep Bista⁶, Derek Wachtel⁷, Sachin Chandran⁸, Rafif Dagher⁹, Dominic Picarella⁹, Angelika Fretzen⁸, Andy Nichols¹⁰, Joanne Donovan⁵

¹Dmpk And Clinical Pharmacology, Catabasis Pharmaceuticals, Inc., Cambridge, MA, US;²Nemours Children’s Hospital, Orlando, FL, US;³Myology Institute, University of Florida Health Myology Institute, Gainesville, FL, US;⁴Physical Therapy, 4University of Florida Health Physical Therapy, Gainesville, FL, US;⁵Clinical Operations, Catabasis Pharmaceuticals, Inc., Cambridge, MA, US;⁶Biology, Catabasis Pharmaceuticals, Inc., Cambridge, MA, US;⁷Biology Analytical, Catabasis Pharmaceuticals, Inc., Cambridge, MA, US;⁸Product Development, Catabasis Pharmaceuticals, Inc., Cambridge, MA, US;⁹Pharmacology & Toxicology, Catabasis Pharmaceuticals, Inc., Cambridge, MA, US;¹⁰Research And Development, Catabasis Pharmaceuticals, Inc., Cambridge, MA, US

Background: Duchenne muscular dystrophy (DMD) is a progressively debilitating and ultimately fatal inherited neuromuscular disorder caused by mutations in the gene encoding dystrophin. NF-kB is activated in DMD and drives inflammation and fibrosis, muscle degeneration and suppresses muscle regeneration. Edasalonexent is an oral small molecule that inhibits NF-κB. In the Phase 2 and the open-label extension (OLE) portions of the MoveDMD trial enrolling 4- to 7-year-old boys with DMD, edasalonexent given 33 mg/kg three times daily (TID) (100 mg/kg/day) demonstrated a preservation of muscle function and slowing of DMD disease progression through 60 weeks as compared to the rates of change during the control period prior to edasalonexent treatment. Methods: The MoveDMD Trial was designed to evaluate efficacy, safety/tolerability, pharmacokinetics (PK), pharmacodynamics (PD), and dose response of edasalonexent. The Phase 1 portion of the MoveDMD trial was a 1-week study to evaluate the safety, PK, and PD at 33 and 67 mg/kg/day, given in 2 divided doses, and 100 mg/kg/day given in 3 divided doses. Phase 2 was a 12-week placebo-controlled study with two cohorts given 33 mg/kg twice daily (BID) (67 mg/kg/day) and 33 mg/kg TID (100 mg/kg/day). Patients in the OLE continued with either dose regimen of edasalonexent. The dose schedule for the Phase 2 of the MoveDMD trial was selected based on nonclinical and clinical data including (1) the exposure/efficacy relationship observed in animal models; (2) the Phase 1 safety, tolerability, and PD in pediatric DMD patients; and (3) human PK. In the mdx mouse model of DMD, dose efficacy was driven by sustained systemic exposure. An oral dose of edasalonexent given TID showed greater pharmacological effects than the same dose given all at once daily despite similar AUC. Results: In the Phase 1 of MoveDMD trial, all three doses were well tolerated with no safety signals observed. Decreases in NF-kB driven gene expression were observed at total daily doses of 67 and 100 mg/kg, both of which were selected for the Phase 2 of MoveDMD trial. In Phase 1 PK studies in healthy volunteers, edasalonexent exhibited increasing exposure with food. Exposure plateaued at 33 mg/kg when administered with a low-fat meal. Patients typically eat meals three times per day, which as a practical matter limits dosing frequency to TID. To validate 33 mg/kg TID that provides sustained systemic exposure, a population PK model was developed and used to simulate the plasma concentration-time profile of 33 mg/kg TID and BID to reflect the regimen of Phase 2 of the MoveDMD trial. Coverage over the concentration range at which pharmacological activity was observed in the nonclinical model was greater with TID than with BID. Conclusion: In conclusion, data from preclinical studies highlight the importance of time above exposure threshold achieved by more frequent dosing. Consistent with nonclinical studies and human PK characteristics of edasalonexent, 33 mg/kg TID dose schedule in the Phase 2 and OLE portions of the MoveDMD trial showed positive dose response vs. 33 mg/kg BID and exhibited numerical improvements in physical function assessments vs. the off-treatment control period.

PS1Group1-061 / #816REPURPOSING TAMOXIFEN FOR SEVERE MYOPATHIES: FROM PRECLINICAL EVALUATION IN ANIMAL MODELS TO CLINICAL TRIALS IN PATIENTS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Olivier M. Dorchies¹, Elinam Gayi², Hesham M. Ismail², Laurence A. Neff², Xènia Massana-Muñoz³, Belinda S. Cowling³, Jocelyn F. Laporte³, Talya Dor⁴, Dirk Fischer⁵, Urs T. Ruegg², Leonardo Scapozza²

¹School Of Pharmaceutical Sciences, University of Geneva, Geneva, CH;²School Of Pharmaceutical Sciences, University of Geneva, Geneva, CH;³Department Of Translational Medicine And Neurogenetics, University of Strasbourg, Illkirch, FR;⁴Hadassah Medical Centre, Jerusalem, IL;⁵Department of Neurology, University of Basel Hospital, Basel, CH

Background: Duchenne muscular dystrophy (DMD), X-linked centronuclear (myotubular) myopathy (XLCNM/XLMTM) and congenital muscular dystrophy type 1A (MDC1A) are rare and fatal muscular diseases for which no cure exists. DMD is caused by the lack of dystrophin, a large protein that connects the extracellular matrix to the cytoskeleton in muscle fibres. DMD patients develop progressive muscle wasting, leading to cardiac and respiratory failure and death usually in their third decade. XLCNM is due to loss-of-function mutations in MTM1, a gene encoding the lipid phosphatase myotubularin. XLCNM patients show generalized hypotonia from birth and most of them die before the age of 2. The pathogenic mechanisms of XLCNM involve imbalance of phosphoinositide levels and of proteins involved in formation and trafficking of membrane vesicles. MDC1A is due to reduced levels or lack of laminin alpha-2, an extracellular matrix protein that plays critical roles in the stability of skeletal muscles and signalling to the myofibres. MDC1A patients show generalized hypotonia from birth and severe respiratory insufficiency. Methods: Tamoxifen, a selective oestrogen receptor modulator, is used for nearly 40 years to treat hormone-dependent breast cancers. We have tested the efficacy of tamoxifen in mdx^5Cv mice, Mtm1-null mice and dy^W mice, models of DMD, XLCNM and MDC1A, respectively. Results: We previously published that long-term tamoxifen improved the symptoms of DMD in mdx^5Cv mice, of which force generation and fibrosis in the diaphragm and in the heart. Follow-up studies showed that tamoxifen doses as low as 0.3 mg/kg/day were efficacious. In 2017, tamoxifen was granted an Orphan Drug Designation for DMD by the European Medicines Agency. Based on our robust pre-clinical data, Talya Dor offered tamoxifen as a compassionate treatment to 3 DMD boys for over 24 months. Because of encouraging outcomes, she is now conducting a larger open-label trial with 30 DMD boys. In parallel, Dirk Fischer is leading “TAMDMD”, a multicentre, randomized, placebo-controlled, phase 3 clinical trial for assessing tamoxifen efficacy and safety in 100 DMD boys. Using the murine model of XLCNM, we found that clinically relevant doses of tamoxifen (3 mg/kg/day) corrected hallmarks of the disease, resulting in dramatic extension of the lifespan of XLCNM mice from around 40 days to >200 days. In dy^W mice, the murine model of MDC1A, preliminary findings suggest that tamoxifen modestly increases the lifespan of affected mice, although it significantly enhances motor function as evaluated with a grid hanging test. Conclusion: Our work reveals the efficacy of tamoxifen in a variety of severe muscular diseases that have independent pathogenic mechanisms, as well as previously unrecognized roles of estrogen signalling as a disease modifier pathway in these fatal diseases. Our preclinical evaluation of tamoxifen in mdx^5Cv mice paved the way to compassionate use and clinical trials for DMD boys. Hopefully, the launch of TAMDMD may increase the interest of clinicians for tamoxifen and accelerate clinical evaluation of that drug in patients with XLCNM. Further work is ongoing in our lab for evaluating the efficacy of tamoxifen for MDC1A.

PS1Group1-062 / #862THE CLINICAL VARIATION OF RYR1 GENE IN A LARGE FAMILY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Stacey Jankelowitz

Central Clinical School, University of Sydney, Sydney, AU

Background: RYR1 gene mutations are many and their clinical presentations are varied. There are at least 217 mutations of the gene that can result in malignant hyperthermia. The RYR1 gene codes for the ryanodine receptor which permits the passage of calcium ions in cells. Methods: This study describes the various manifestations of a single RYR1 gene mutation in a large family, including the proband, her children, her mother and her siblings. The presenting features and severity while linked and described are varied within the one family. Results: A single gene mutation may result in mild scoliosis, malignant hyperthermia and miscarriage as well as ptosis, kyphoscoliosis and weakness. The study of epigenetics will hopefully aid in the understanding of these disorders and their variable presentation. Conclusion: While gene tests are useful in determining the mutation responsible for clinical disorders, there is more to be learnt from gene expression to explain why a single gene disorder can have such varied presentation and differ in the severity of the illness within one family.

PS1Group1-063 / #940CLINICAL OUTCOME STUDY OF DYSFERLINOPATHY: WHAT ARE THE BEST FUNCTIONAL AND STRENGTH OUTCOME MEASURES FOR THIS POPULATION?

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Volker Straub¹, Meredith James¹, Anna Mayhew¹, Marni Jacobs², Jia Feng², Simone Spuler³, Kate Bushby¹, John Day⁴, Kirsti J. Jones⁵, Diana X. Bharucha-Goebel⁶, Emmanuelle Salort-Campana⁷, Alan Pestronk⁸, Maggie C. Walter⁹, Carmen Paradas¹⁰, Tanya Stojkovic¹¹, Madoka Mori-Yoshimura¹², Elena Bravver¹³, Jordi Diaz-Manera¹⁴, Elena Pegoraro¹⁵, Jerry Mendell¹⁶

¹John Walton Muscular Dystrophy Research Centre, Newcastle University, Institute of Genetic Medicine, Newcastle Upon Tyne, GB;²Division Of Biostatistic And Study Methodology, Children’s National Health System, Centre for Translational Science, DC, WA, US;³Charite Muscle Research Unit, Experimental and Clinical Research Center, Berlin, DE;⁴Department Of Neurology, Stanford University, Palo Alto, CA, US;⁵Institute For Neuroscience And Muscle Research, Children’s Hospital At Westmead, University of Sydney, Sydney, AU;⁶Department Of Neurology, Children’s National Health System, Washington DC, US;⁷Neuromuscular And Als Center, La Timone Hospital, Aix-Marseille Universite, Marseille, FR;⁸Department Of Neurology, Washington University School of Medicine, St. Louis, MO, US;⁹Dept. Of Neurology, Ludwig-maximilians-university, Friedrich-Baur-Institute, Munich, DE;¹⁰Neuromuscular Unit, Department Of Neurology, Hospital U. Virgen del Rocio/Instituto de Biomedicina de Sevilla, Sevilla, ES;¹¹Ap-hp, G.h. Pitié-salpêtrière 47-83, Boulevard De L’hôpital, Institut de Myologie, Paris, FR;¹²Department Of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, JP;¹³Carolinas Healthcare System Neurosciences Institute, Charlotte, NC, US;¹⁴Neuromuscular Disorders Unit, Hospital de la Santa Creu i Sant Pau, Barcelona, ES;¹⁵Department Of Neuroscience, University of Padova, Padova, IT;¹⁶Center For Gene Therapy, Nationwide Children’s Hospital, Columbus, OH, US

Background: Dysferlinopathy, an autosomal recessive form of limb girdle muscular dystrophy, clinically presents with a variable spectrum of muscle weakness. The Clinical Outcome Study is an international 3 year natural history study of dysferlinopathy patients, which aims to gain a better understanding of the disease and to improve clinical trial readiness. Diagnostic criteria for inclusion in this study were a) two predicted pathogenic mutations or b) one predicted pathogenic mutation and absent mutation or c) one predicted pathogenic mutation and dysferlin protein level less than 20% as determined by blood monocyte testing. The cohort is 52% female 48% male. At baseline the ration of ambulant to non-ambulant was 3:1. The mean age was 40 years (range 12 to 88 years). The median years disease duration was 17 years (range 3-52 years). Here we aim to describe changes in functional outcome measures and muscle strength over a 2 year period in individuals with dysferlinopathy. Methods: 197 subjects across 15 sites in 8 countries underwent physiotherapy assessments including muscle strength (manual muscle testing, MMT; hand held dynamometry, HHD); and functional performance using the North Star Assessment for Dysferlinopathy (NSAD), Brooke score and Performance of Upper Limb, as well as timed tests (rise from floor, 10 metre walk / run, four stair climb and descend; Timed Up and Go, TUG; Six Minute Walk Distance), and respiratory function testing (forced vital capacity, FVC). Change was defined as significant difference in paired medians by Wilcoxon Signed Rank-Sum test (p<0.05). Results: Change is captured in this population consistently from baseline to year 1 and from year 1 to year 2 across a range of functional outcome measures. Motor performance assessed by NSAD demonstrated slow but consistent and significant deterioration in scores and confirmed NSAD as a dysferlin specific scale. All timed tests except rise from floor showed significant consistent decline between year 1 and year 2. Of the muscle groups assessed by HHD that showed ­significant change, the plantar flexors were the muscles with the highest mean differences (3.14 lbs, SD: 8.22). We detected a mild but significant decrease in FVC (mean difference 0.09L) Conclusion: Progression in dysferlinopathy can be demonstrated using functional outcomes and dynamometry as measured by physiotherapists over two years. Change between baseline, year 1 and year 2 were slow but relatively consistent and significant. Results will help to power future clinical trials.

PS1Group1-064 / #294BREATHING IS LIFE! INSPIRATORY MUSCLE TRAINING IN CHILDREN AND ADOLESCENTS LIVING WITH NEUROMUSCULAR DISEASES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Anri Human¹, Jennifer Jelsma², Brenda M. Morrow³

¹Physiotherapy, Sefako Makgatho Health Sciences University, Garankuwa, ZA;²Division Physiotherapy, University of Cape Town, Observatory, ZA;³Paediatrics And Child Health, University of Cape Town, Rondebosch, ZA

Background: People with neuromuscular diseases (NMD) have a high risk of morbidity and mortality caused by underlying respiratory muscle weakness and an ineffective cough. Inspiratory muscle training (IMT) aims to preserve or improve respiratory muscle strength; reduce morbidity; optimise ventilation and ultimately improve health-related quality of life (HRQoL). Inspiratory muscle training among children and adolescents with NMD is controversial, owing to differences in pathophysiology and potential risk of muscle damage in some conditions. Despite reports of potential benefits, there is insufficient evidence to guide clinical practice regarding the use of IMT in this sub-population. Methods: A pre-experimental, observational pre-test post-test study was used to determine changes in measures of spirometry, peak expiratory cough flow (PECF), inspiratory muscle strength , upper limb function and coordination (using the Motor Function Measurement (MFM) scale), adverse events and HRQoL (using the PedsQL tool). Eight participants (n=4 boys; mean age 12.71 ± 3.53 years) with a variety of NMD were included. Training consisted of 30 breaths, twice daily, five days a week, for six weeks with an electronic threshold device (Powerbreathe K3, HaB International Ltd, Southam, UK). Results: There were no significant changes in spirometry measures, PECF or HRQoL. Upper limb function and coordination (MFM score) improved from pre-to post-intervention (p<0.04). Measures of inspiratory muscle strength also improved significantly: maximal inspiratory mouth pressure (Pimax) (p<0.02), strength-index (p<0.02) and peak inspiratory flow (p<0.03). No adverse events occurred during the intervention period. Overall patient satisfaction with the IMT programme, on a 10-point visual analogue scale, was extremely high, with a median (IQR) of 9 (9-10). Conclusion: This study suggests that short term IMT may improve inspiratory muscle strength; as well as improving upper limb function and coordination. IMT may be a safe and effective adjunct intervention for children and adolescents with NMD, but larger, long-term randomised controlled trials are recommended.

PS1Group1-065 / #490PERSONALIZED MOLECULAR THERAPY IN A NEW TRANSLATIONAL LARGE ANIMAL MODEL FOR DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Tina Donandt¹, Simone Reichert¹, Maria Schmuck¹, Claudia Kalbe², Barbara Kessler³, Andreas Blutke⁴, Eckhard Wolf⁵, Sabine Krause¹, Maggie C. Walter¹

¹Dept. Of Neurology, Ludwig-maximilians-university, Friedrich-Baur-Institute, Munich, DE;²Institute Of Muscle Biology And Growth, Leibniz Institute for Farm Animal Biology (FBN), Dummerstorf, DE;³Department Of Biochemistry, Molecular Animal Breeding And Biotechnology, Ludwig-Maximilians-University, Munich, DE;⁴Institut Für Tierpathologie, Ludwig-Maximilians-University, Munich, DE;⁵Gene Center And Department Of Biochemistry, Molecular Animal Breeding And Biotechnology, Ludwig-Maximilians-University, Munich, DE

Background: The development of efficient and safe gene therapy approaches in muscular dystrophies is a major challenge. Cell culture models derived from our large animal model, the DMD pig, provide an in vitro system to qualitatively and quantitatively evaluate therapeutic restoration of dystrophin. The DMD pig carries an exon 52 deletion in the dystrophin gene and mimics the most frequent human DMD mutation. A major hurdle is the low degree of myogenic differentiation in porcine satellite cells. As compared to other species, terminal differentiation of porcine myoblasts is very inefficient. Moreover, full-length dystrophin (Dp427) is not expressed until after the myoblasts begin myogenic differentiation. Methods: Primary satellite cells were isolated from pig skeletal muscle by consecutive enzymatic digestion. The fusion medium and the surface coating were optimised to facilitate myotube formation. Differentiation medium containing Ultroser G and matrigel/gelatin coated culture dishes promoted myotube surface adherence and maturation. Low levels of dystrophin protein in differentiating porcine cells demanded also an improvement of the Western blot technique. To enrich for myotubes, differential trypsination was successfully employed to yield sufficient differentiated cells for dystrophin Western blot detection. Results: Among key factors which affect myogenesis in vitro are the extracellular matrix proteins chosen to coat the culture plates and the choice of growth and differentiation media. Notably, a preplating step for 1-2 h did not improve the yield of myogenic cells. By means of optimised fusion media and culture dish coating, we significantly improved myogenic differentiation in terms of fusion index and dystrophin protein expression. It is well established that dystrophin is a low-abundance protein and constitutes less than 0.01% of total striated muscle protein. For protein extraction and Western blot detection in the porcine cell culture model, we enriched for myotubes to increase the dystrophin specific signal. Conclusion: Differentiated dystrophin-deficient porcine myoblasts provide a primary exon 52-deficient cell culture model ideally suited for evaluation of targeted RNA- or DNA-based molecular therapy. The efficiency of dystrophin restoration, potential toxicity, and additional side effects may be assessed by our preclinical approach and provides excellent translational impact for future treatment options in affected DMD patients.

PS1Group1-066 / #605DILATED CARDIOMYOPATHY AND LIMB-GIRDLE MUSCULAR DYSTROPHY-DYSTROGLYCANOPATHY REVEALING NEW DPM3 GENE MUTATIONS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Juliette Svahn¹, Pascal Laforet², Christophe Vial³, Nathalie Streichenberger⁴, Norma Romero⁵, Céline Bouchet-Séraphin⁶, Nathalie Seta⁷, Rita Menassa⁸, Françoise Bouhour³, Guillemette Jousserand³, Tanya Stojkovic²

¹Electroneuromyography And Neuromuscular Department, Hospices Civils de Lyon, Bron, FR;²Sorbonne Universités, UPMC Univ Paris 06, INSERM UMRS974, CNRS FRE3617, Center of Research in Myology, Myology Institute, Paris, FR;³Electroneuromyography And Neuromuscular Department, Hospices Civils de Lyon, Bron, FR;⁴Centre de Neuropathologie Est - Hospices Civils de Lyon, Université Claude Bernard Lyon1, Institut NeuroMyogène - CNRS UMR 5310 - INSERM U1217, Bron, FR;⁵Unité De Pathologies Neuromusculaires, Institut De Myologie, UMRS974, Institut de Myologie, Paris, FR;⁶Département De Biochimie Et De Génétique, AP-HP, Hôpital Bichat, Paris, FR;⁷Biochemistry Laboratory, AP-HP, Hôpital Bichat, Paris, FR;⁸Department Of Molecular Endocrinology And Rare Diseases, Hospices Civils de Lyon, Bron, FR

Background: DPM synthase catalyzes the formation of DPM from Dolichol-phosphate and GDP-mannose(Man). The deficiency of Dolichol-P-mannose (DPM) synthase subunit 3 (DPM3) affects two particular glycosylation pathways: N-glycosylation and O-mannosylation which are respectively involved in congenital disorders of glycosylation (CDG) and alpha-dystroglycanopathies. Aberrant glycosylation of alpha-dystroglycan (aDG) leads to alpha-dystroglycanopathies. We describe novel pathogenic DPM3 mutations previously unreported in the literature in two unrelated male patients presenting limb-girdle muscular dystrophy (LGMD) and dilated cardiomyopathy. Methods: Clinical examination, cardiac and biologic investigations, muscle imaging, muscle biopsy and transferrin isoelectric focusing were performed. Next generation sequencing of 18 alpha-dystroglycanopathies genes was performed (B3GALNT2, B3GNT1, DAG1, DOLK, DPM1, DPM2, DPM3, FKRP, FKTN, GMPPB, ISPD, LARGE, POMGNT1, POMGNT2, POMK, POMT1, POMT2, TMEM5). Results: The two patients presented early and severe dilated cardiopathy, which turned out to be the main symptom in one of our patient. They developed limb-girdle muscular dystrophy predominating in pelvic girdle, in childhood and adulthood respectively. Laboratory investigations revealed elevated CK level. The deltoid muscle biopsies of both patients revealed moderate muscle dystrophy with fiber-size variation, multiple internal nuclei, and interstitial fibrosis. Immunolabelling of aDG (VIA4-1 antibody, Millipore) showed reduced alpha-dystroglycan immunostaining in patient 1 and thin and irregular sarcolemmal staining in patient 2. Muscle imaging displayed diffuse fatty degeneration in gluteus muscles, rectus femoris muscles and lower limb muscles with severe fatty replacement in the adductors, hamstrings and triceps surae muscles. Transferrin isoelectric focusing of both patients revealed an abnormal profile suggesting a congenital disorder of glycosylation (CGD) type 1 pattern, consistent with defective N-glycosylation (DPM3-CGD1). Next generation sequencing uncovered in the two patients a hemizygous deletion of DPM3 and a hemizygous pathogenic missense mutation in exon 2 c.41T>C, p.Leu14Pro, predicted to be pathogenic by in silico tools. Conclusion: Previously, defects in N-glycosylation and O-mannosylation were considered to cause separate groups of diseases but cases have been since described which linked congenital disorders of glycosylation (CDG) type I with dystroglycanopathies. DPM3 mutations have been previously reported in two patients. Lefeber et al., described a female child with mild LGMD2 and a homozygous missense mutation, who developed dilated cardiomyopathy in early adulthood (Lefeber et al., 2009). Recently, an adult female patient with isolated pelvic girdle muscle weakness and a homozygous missense mutation was reported (Van Den Bergh et al., 2017). In conclusion, patients with DPM3 mutations may present with a particular phenotype: mild to severe limb-girdle muscular dystrophy predominating in the pelvic girdle, early dilated cardiomyopathy and biochemical features of deficient protein N-glycosylation. These observations underline the importance of considering a DPM synthase defect in unsolved alpha-dystroglycanopathy patients and of performing serum N-glycosylation screening.

PS1Group1-067 / #637DYSFERLINOPATHY: PHENOTYPIC ASPECTS IN 24 MOROCCAN PATIENTS AND BENEFITS FROM MUSCLE EXERCISE AND CORTICOIDS IN SOME CASES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Nazha Birouk¹, Sana Sefiani², Bouchra Kably³, Halima Belaïdi³, Reda Ouazzani³

¹Clinical Neurophysiology Rabat, Speciality Hospital, Rabat, MA;²Neuropathology, Speciality Hospital, Rabat, MA;³Clinical Neurophysiology, Speciality Hospital, Rabat, MA

Background: Dysferlin deficiency is responsible for different phenotypes of muscle dystrophies including limb girdle syndrome and distal myopathies. This work aims to give a phenotype description of dysferlin deficient patients belonging to 22 Moroccan families and to describe the benefit from regular muscle exercise and corticosteroid treatment in some patients. Methods: All patients underwent clinical evaluation for muscle impairment distribution and orthopedic signs, CK dosage, electroneuromyography and muscle biopsy with immunocytochemistry for dystrophin, sarcoglycans and dysferlin. 3 patients received oral prednisone and 5 patients had a regular follow up with muscle exercise. Results: Twenty four patients aged 14 to 57 years were examined. There were 15 males and 9 females. Age at onset was 20,2±6,7 years (range: 12 to 35). 16 families had an established consanguinity, 11 families had more than 1 affected member. The phenotypes were as follows: Myoshi type in 7 patients, limb girdle syndrome was isolated in 5, associated to lower limbs distal muscles involvement in 7, to biceps brachialis muscles deficit in 4 and to tibialis anterior impairment in 1 patient. CK level was 1.5 to 6 X normal value. 3 patients had myalgia and inflammatory pattern on muscle biopsy. 1 patient had asymptomatic high CKemia. All patients had dystrophic changes on muscle biopsy with absence of dysferlin where as dystrophin and sarcoglycans were normal on immunocytochemistry. Functional disability was variable, 3 patients were wheel chair bound at the ages of 23, 25 and 38 years respectively. 3 patients received treatment with oral prednisone with a drastic benefit on functional disability. 5 patients had a sustained functional benefit from regular muscle exercise that was adapted to their deficits. Conclusion: Dysferlin deficiency was identified in 41.5% of muscle dytrophy families with limb girdle and or distal muscles impairment in our series. It seems to represent the second cause of muscle dystrophies in Morocco after sarcoglycanopathies. A screening for the responsible dysferlin gene mutations is necessary to identify a probable founder mutation in our population. We should consider the potential benefit from corticosteroids and regular muscle exercise in some patients.

PS1Group1-068 / #614LGMD DUE TO γ-SARCOGLYCAN DEFICIENCY (LGMD2C): STUDY OF NATURAL HISTORY IN 77 PATIENTS BELONGING TO 69 MOROCCAN FAMILIES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Nazha Birouk¹, Armel Ghislain Mpandzou¹, Bouchra Kably², Sana Sefiani³, Abdelaziz Sefiani⁴, Halima Belaïdi², Reda Ouazzani²

¹Clinical Neurophysiology Rabat, Speciality Hospital, Rabat, MA;²Clinical Neurophysiology, Speciality Hospital, Rabat, MA;³Neuropathology, Speciality Hospital, Rabat, MA;⁴Genetic, National Health Institut, Rabat, MA

Background: Sarcoglycanopathies (SGP) are autosomal recessive progressive limb-girdle muscular dystrophies, due to α-, β-, γ- and δ-sarcoglycan gene mutations, respectively leading to LGMD (limb girdle muscular dystrophy) 2D, E, C and F. In North Africa, γ-SG is the most common. We report a study of 77 patients from 69 Moroccan families with highlights to the disease progression. Methods: Throughout a 21-year time lapse, 77 patients, among 133 SGP, were regularly followed-up during an average time of 4.1 ± 3.4 years (SD) [Max:Min; 1-14]. Diagnosis of γ-SGP was established on protein immunostaining and/or genetic analysis (n = 69) and by findings obtained from siblings (n = 8). Disease progression was assessed annually in all patients by frequency, age and delay of the occurrence of the main functional incapacities, skeletal deformities, cardiac and respiratory impairments and by survival curve of the loss of ambulation. Functional scores (Research Medical Council, Vignos, modified Gardner-Medwin-Walton, walking distance and climbing stairs) were calculated in 35 patients regularly followed-up during five years. Results: Consanguinity rate was 69.6% (48/69 families), 40 (51.9%) patient were sporadic cases and 37 (48.1%) had positive familial history. Sex ratio was 0.8. Immunostaining analysis showed isolated γ-SG deficiency in 57/67 (85.1%) patients investigated and combined γ-SG deficiency with reduction of one or more other SG in 10/67 (14.9%). Genetic analysis showed Δ525T mutation in 15/23 (65.2%) patients investigated. Mean age at onset was 7.2 ± 2.8 years [1-19]. Loss of ambulation occurred after 7.5 ± 4.6 years [2-22] of disease duration; almost concomitant with scoliosis. From Kaplan Meier survival curve, median of loss ambulation was 8 ± 0.5 years (95% CI 7.03-8.96 years) with probability of 44.4%. Comparison tests of delay of the loss of ambulation showed no significant difference for gender, family history, parental consanguinity, and expression profile of γ-SG deficiency. Cardiac impairment was found in 10/53 (18.8%) patients at a mean age of 18.8 ± 10.6 years [8-45]. Main cardiac anomalies were left ventricular dysfunction either isolated or associated with dilated cardiomyopathy in 7/10 patients, incomplete right bundle branch block in 5/10, premature ventricular contraction in 3/10, and right ventricular dysfunction in 1/10. Restrictive respiratory syndrome was found in 21/24 (87.5%) patients at a mean age of 18.9 ± 8.2 years [9-43]; this syndrome became severe requiring non-invasive ventilation in 10 patients, at a mean age of 21.5 ± 9.4 years [11-43]. In the 35 patients selected for the functional assessment, scores measures changes were most significant in patients with loss of ambulation or in patients with early age at onset between 5-9 years. Conclusion: The analysis of SG natural history highlights disease prognosis and can thus help in anticipating medical management to improve patient’s quality of life.

PS1Group1-069 / #659DOES A NORMAL DYSTROPHIN STAINING IN MUSCLE BIOPSY RULE1 OUT THE MOLECULAR DIAGNOSIS OF DUCHENNE / BECKER MUSCULAR DYSTROPHY?

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Mira Ginzberg, Tally Lerman-Sagie, Dorit Lev, Ron Dabby, Menachem Sadeh, Esther Leshinsky-Silver

E. Wolfson M.D, Holon, IL

Background: Molecular genetic testing of the Dystrophin gene can confirm the clinical diagnosis of a dystrophinopathy without muscle biopsy in most individuals with Dhchenne uscular Dystrophy / Becker Muscular Dystrophy (DMD/BMD). The multiplex ligation-dependent probe amplification (MLPA) assay is the most powerful tool in screening for deletions and duplications in the dystrophin gene in patients with (DMD/BMD). Deletions of one or more exons account for about 65 % of DMD and about 85 % of BMD cases. MLPA is a quantitative method enabling the detection of deletions and duplications of all 79 DMD exons. MLPA can determine the size of the deletion or duplication and predict, whether the mutation disrupt the reading frame Methods: We describe two male siblings, born to healthy non consanguineous parents. Both have suffered since a young age from muscle weakness and recurrent episodes of rhabdomyolisis with high CK values. The muscle weakness has been improving constantly and now as grownup males, they have minimal selective proximal girdle muscle weakness. However, the older brother experiences recurrent episodes of severe rhabdomyolysis and atrial fibrillation. The younger brother, experiences fatigability and lately dilated cardiomyopathy was diagnosed. Their maternal grandfather, who died at the age of 39 years, because of cardiomyopathy, did not suffer from ­­­­­myopathy. Results: We describe two male siblings, born to healthy non consanguineous parents. Both have suffered since a young age from muscle weakness and recurrent episodes of rhabdomyolisis with high CK values. The muscle weakness has been improving constantly and now as grownup males, they have minimal selective proximal girdle muscle weakness. However, the older brother experiences recurrent episodes of severe rhabdomyolysis and atrial fibrillation. The younger brother, experiences fatigability and lately dilated cardiomyopathy was diagnosed. Their maternal grandfather, who died at the age of 39 years, because of cardiomyopathy, did not suffer from ­­­­­myopathy. Conclusion: Exon 1 deletion in the Dystrophin gene is the cause for BMD in these two brothers and probably the cause for cardiomyopathy in their grandfather. If the clinical presentation and the pattern of inheritance is suspicious enough, only molecular analysis of the dystrophin gene by sequencing and MLPA can lead us to the correct diagnosis. However, there are some pitfalls of MLPA in detecting DMD single exon deletion or duplication, because of false-positives due to sequence variations.

PS1Group1-070 / #820ESYN- AND CK9- PROMOTORS DRIVE MUSCLE-SPECIFIC EXPRESSION OF TRANSGENES IN VITRO AND IN VIVO

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Jinhong Meng¹, John Counsell², Simon Waddington³, Francesco Muntoni⁴, Jennifer Morgan⁵

¹UCL Great Ormond Street Institute of Child Health, London, GB;²UCL Great Ormond Street Institute of Child Health, London, GB;³EGA Institute for Women’s Health, London, GB;⁴Dubowitz Neuromuscular Unit, UCL Great Ormond Street Institute of Child Health, London, GB;⁵University College London, London, GB

Background: Lentivirally-mediated dystrophin expression is a promising therapeutic approach for Duchenne muscular dystrophy (DMD). Lentivirus coding either full-length or mini- dystrophin can transduce patient-derived muscle stem cells, providing a valuable cell source for autologous transplantation. However, due to the large size of the dystrophin gene and the limited packaging capacity of the lentiviral vector, the promoter driving the transgene expression needs to be small. Furthermore, as dystrophin is mainly expressed in muscle fibres, the promoter must be active in differentiated muscle cells. Methods: In the present study, we tested the expression of a reporter gene driven by either ESyn- (547bp) or CK9- (429bp) promoters in comparison to the ubiquitous SFFV promotor, by transducing lentiviruses coding luciferase driven by the ESyn- , CK9- or SFFV- promoter into cultured human cells derived from lung, liver, kidney, neuroblastoma and skeletal muscle. Furthermore, these viruses were injected systemically into newborn outbred mice and the expression of luciferase was examined one month later using the IVIS Lumina III in vivo imaging system. Results: We found that cells transduced with ESyn- and CK9- lentivirus express significantly lower levels of luciferase in comparison to those transduced with SFFV- lentivirus. Interestingly, the expression of luciferase was dramatically increased in Esyn- and CK9- lentivirus-transduced muscle cells when they were induced to undergo myogenic differentiation. In mice injected with SFFV- lentivirus, luciferase was expressed in organs including liver, spleen and skeletal muscle, while in mice injected with Esyn- or CK9- lentivirus, luciferase was expressed mainly in skeletal muscles. Conclusion: our data show that both ESyn- and CK9- promoters drive skeletal muscle specific expression of a transgene, indicating that they are good candidates for driving expression of proteins within skeletal muscle.

PS1Group1-071 / #354E-CADHERIN IS ECTOPICALLY EXPRESSED IN THE MUSCLE FIBER OF INCLUSION BODY MYOSITIS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Chiseko Ikenaga, Hiroyuki Ishiura, Hidetoshi Date, Akatsuki Kubota, Shoji Tsuji, Tatsushi Toda, Jun Goto, Jun Shimizu

Department Of Neurology, The University of Tokyo, Tokyo, JP

Background: Both inclusion body myositis (IBM) and polymyositis (PM) are characterized by the endomysial infiltrates of CD8+ cytotoxic T-lymphocytes invading or surrounding major histocompatibility class 1 expressing non-necrotic muscle fibers (CD8-MHC-1 complex). Patients with IBM have rimmed vacuoles or abnormal protein accumulation and they are refractory to treatments, while patients with PM generally respond well to treatments. It seems to be important to clarify genes or pathways, which contribute to the difference of these two disease’s phenotypes. Methods: We analyzed frozen muscle biopsy samples from 62 patients with CD8-MHC-1 complex (43 IBM, 9 PM, and 10 unclassifiable) and 9 normal controls (NCs) by RNA-sequencing (Illumina Hiseq 2500). We detected the differentially expressed genes (DEGs) and performed pathway analysis by edgeR. In addition, we compared the gene expressions of cell surface antigens (CD1~CD371) among these groups. In order to evaluate the protein level of these DEGs and cell surface antigens, we performed immunohistochemistry on frozen sections of muscle biopsy samples from patients with IBM, PM, dermatomyositis (DM), immune-mediated necrotizing myopathy (IMNM), and NCs, respectively. Results: Compared with NCs, there were 8588 DEGs in IBM (FDR<0.05) and the sets of genes concerning cancer, immune system, and NFkB/TNF/PI3K-Akt/JAK-STAT/TGF-ß signaling pathways were upregulated, while the sets of genes concerning translation, transcription, and mitochondrial function were downregulated in IBM. Compared with NCs, there were 4744 DEGs in PM (FDR<0.05) and the sets of genes, which were upregulated or downregulated in PM, were the same as those in IBM. When we compared IBM with PM, there were 1419 DEGs (FDR<0.05) and the gene sets of the innate and adaptive immune systems were more upregulated in IBM than those in PM. Among these DEGs, there were 28 genes, in which the expressions of IBM were twice as much as those of PM (FDR<0.05) and 12 genes of cell surface antigens including E-cadherin (FDR<0.01). In immunohistochemistry, the muscle fibers of IBM, which were diffusely positive for p62, were also positive for E-cadherin. On the other hand, the muscle fibers, which were positive for dense p62 aggregates, were not stained with E-cadherin antibody. Although there were some muscle fibers, which were diffusely positive for p62 in the samples of IMNM and DM, they were not stained with E-cadherin antibody, except for the partial staining of perifascicular fibers with atrophy in DM. Conclusion: IBM and PM shared most of the upregulated/downregulated pathways. Among them, the gene sets of the innate and adaptive immune systems were upregulated in the muscle of IBM, compared with those of PM. Among the DEGs, E-cadherin, which is known to be expressed in the epidermis, was highly expressed in the muscle of IBM. Considering the ectopical expression and the unique staining pattern of E-cadherin in the muscle of IBM, it may have some roles in the pathogenesis of IBM.

PS1Group1-072 / #399CARE EVALUATION OF DUCHENNE MUSCULAR DYSTROPHY PATIENTS IN BRAZIL

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Karine C. Turke, Alzira A.S. Carvalho, David Feder

Faculdade de Medicina do ABC, Santo André, BR

Background: The Duchenne Muscular Dystrophy (DMD) is the most frequent genetic lethal disease in early childhood of boys. International protocols for surveillance and treatment are broadly diffused and our objective was to assess if the patients with DMD in Brazil receive adequate treatment accordingly to those protocols. Methods: Through social networks, parents and responsible person were invited to answer to an online form. The questionnaire addressed conditions of the diagnosis, exams and treatments. Results: 54 patients were included in the study. The average age was 13,0 +1,2 years. 79,62% of the boys was medicated with corticosteroids, where 76,7% used deflazacort; 18,1% prednisolone and 4,65% prednisone. In the diagnosis, 31,4% were submitted to a skeletal muscle biopsy, and 79,6% knew the genetic mutation. 40,7% had cardiac alteration. The first electrocardiogram (ECG) and echocardiogram (Echo) happened at 8,4 and 8,8 years old respectively. The ECG was not performed yearly in only 23,5% of the cases, and the Echo in 26,4%. 50% of the patients went through the holter, and 9,2% was submitted to a cardiac magnetic resonance image. Only 31,4% performed a strength test every 6 months. Just 22,11% of the studied cases attended rehabilitation programs. 79,5% of the patients over 6 years of age performed spirometry, with an average of 10,5 years old. In the assessment of coughing effort only 34,7% of the patients over 6 years old submitted to the exam. The annual spirometry was performed by 48,1% of the participants. 37% had an appointment with occupational therapist and 31,4% with a nutritionist in the last year. 59,2% of the patients had done bone densitometry, and 37,5% of those were diagnosed with osteoporosis. Only 57,4% of the participants was vaccinated against influenza in the last year. Conclusion: It is concluded that the international protocols of surveillance and management of the patients with DMD are not being followed in Brazil. This could contribute to a greater mortality and morbidity. Enhancing medical education about DMD through disclosure protocols as well as providing patient access to specialized health care and medication adherence would be meaningful to improve the quality of life of DMD patients.

PS1Group1-073 / #891GENOTYPE AND PHENOTYPE FEATURES OF BRAZILIAN PATIENTS WITH MCARDLE DISEASE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Alzira A.S. Carvalho¹, Vinicius G. Silva², Miriam E. Koch³, Pamela O. Delgado⁴, Bruno M. Bertassoli², Roseli Corazzini⁴, Karine C. Turke⁴, Denise M. Christofolini⁵, Itatiana Rodart⁵, Fernando L.A. Fonseca⁶, David Feder²

¹Neurology, Faculdade de Medicina do ABC, Santo Andre, BR;²Pharmacology, Faculdade de Medicina do ABC, Santo Andre, BR;³Faculdade de Medicina do ABC, Santo Andre, BR;⁴Faculdade de Medicina do ABC, Santo André, BR;⁵Genetics, Faculdade de Medicina do ABC, Santo Andre, BR;⁶Laboratory Analysis, Faculdade de Medicina do ABC, Santo Andre, BR

Background: Glycogenosis Type V(GTV) also known as McArdle disease, is a rare autosomal recessive disorder characterized by exercise intolerance, myalgia and painful cramping since childhood or adolescence associated to persisted elevated creatine kinase(CK). Mutations in the gene cause the disorder causing inability to produce the enzyme known as phosphorylase or myophosphoryase in muscle. The objective was to analyze clinical, epidemiological and genetic aspects as well as, to demonstrate the morphological muscular findings in 18 patients with McArdle disease. Methods: The clinical parameters evaluated were: cramps, myalgia, fatigue and dark urine. CK, modified ischemic exercise test (TI), hand-grip strength (using dynamometer) were also analyzed. The muscular morphological aspects analyzed were the percentage of internal nuclei, vacuoles and Feret’s using H&E stain. The PYGM gene mutation was analyzed by screening exons 1, 15 and 17 followed by next generation sequencing (TruSight Inherited Disease panel from Illumina Inc.) when the mutation was not found. Results: The total of 18 patients were analyzed: performed muscle biopsy: n=15; CK: n=18; ischemic exercise test(IET) n=16; hand-grip strength: n=16; genetic test: n=14 (the remaining four patients were siblings belonging to three distinct families and presented the same symptoms, elevated CK and muscle biopsy compatible with GTV the four). 56% men; 44% women. Considering clinical symptoms, 66,7% of them refer cramps, 72.2% myalgia, 100% fatigue and 66,7% dark urine. Fibers with internalized nuclei (FIN): 10%; vacuoles: 16,1%; type 2 fiber predominance (T2FP): 62,3%. Feret’s diameter ranged from 21.5 to 83.5 um (type 1) and 34.6-78.2 um (type 2). CK at rest: 1767 U / L (median). IET was consisted with GTV in 100% of patients without side effects. Hand-grip strength was 44.3 kg (median). The morphological parameters vacuoles and FIN were not statistically significant when correlated. The T2FP and Feret’s diameter were significant, p = 0.0000 and p = 0.0007 respectively). The most frequent mutation was R50X in homozygous (50%). The second most frequent was association of R50X and c.1967 A>C (17%). One patient had 4 mutations that “in silica” showed to be pathogenic. There was no correlation among the parameters evaluated, even among members of the same family. Conclusion: 1. CK is not related to the histological alterations analyzed. 2. IT is a good screening test in the differential diagnosis of patients with IE and without risks. 3. The T2FP suggests a compensatory mechanism in the use of fast fiber energy. 4. The R50X Arg50Ter mutation was the most frequent in our sample. Our study was the pioneer in the analysis of the histological phenotype versus genotype. 5. The results regarding the heterogeneity of the parameters analyzed suggest that GTV presents a clinical, histological and molecular individual phenotype. Therefore, genotype and histological phenotype are not prognostic factors of the disease.

PS1Group1-074 / #571PROPOSED CUT-OFF FOR REACTIVITY OF ANTI-HMGCR AND ANTI-SRP ANTIBODIES IN PATIENTS STATIN-EXPOSED AND STATIN-UNEXPOSED

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Alzira A.S. Carvalho¹, Thaiane F. Vieira¹, Miriam E. Koch¹, Vinicius G. Silva¹, Roseli Corazzini¹, Pamela O. Delgado¹, Karine C. Turke¹, Fernando L.A. Fonseca², David Feder³

¹Faculdade de Medicina do ABC, Santo André, BR;²Laboratory Analysis, Faculdade de Medicina do ABC, Santo Andre, BR;³Pharmacology, Faculdade de Medicina do ABC, Santo Andre, BR

Background: Introduction: Few reports have been published demonstrating that anti-HMGCR and anti-SRP are specific to immune-mediated necrotizing myopathy (IMNM). The therapeutic approach with statins is widely used in the control of dyslipidemias. However, there is no laboratory evaluation to elect patients to make use of this class of therapeutic drugs. Aim: To analyze the prevalence of anti-SRP and anti-HMGCR antibodies in a heterogeneous cohort of 85 patients to determine cut-off reference values for these antibodies. Methods: Serum samples from 85 patients were screened for the presence of anti-HMGCR and anti-SRP autoantibodies by ELISA. The demographic, clinical and morphological features were also correlated with anti-HMGCR and anti-SRP antibodies. The patients were divided in two groups; A: statin-exposed and B: statin-unexposed. Results: The mean age of groups A and B were 61.1 and 39.5 years, respectively. Anti-HMGCR and anti-SRP antibodies were present in 12.6% and 14.1% of patients, respectively. 57 statin-exposed and 28 statin-unexposed. There were no significant associations of anti-HMGCR and anti-SRP titers with age, gender, exposure to statins or symptoms; however, significantly more symptomatic patients had been exposed to statins (p = 0.003). There was no significant difference in anti-HMGCR levels between asymptomatic and symptomatic patients (p = 0.994). Conclusion: Our results defined antibody cut-off points for a heterogeneous population with different diagnoses. We also demonstrated that anti-HMGCR and anti-SRP antibodies are not 100% specific for IMNM. Eleven (12.9%) patients were positive for anti-HMGCR antibodies and 12 (14.1%) were positive for anti-SRP antibodies in this heterogeneous cohort.

PS1Group1-075 / #573NECROTIZING MYOPATHY AFTER DENGUE: CASE REPORT

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Alzira A.S. Carvalho¹, Karine C. Turke¹, David Feder²

¹Faculdade de Medicina do ABC, Santo André, BR;²Pharmacology, Faculdade de Medicina do ABC, Santo Andre, BR

Background: Muscle involvement is rare in dengue. Usually just myalgia and rarely as myositis, hypokalemic paralysis, or rhabdomyolysis. Methods: We report a case of necrotizing myopathy occurring in a 38-year-old Caucasian woman was referred to emergency unit care complaining of low grade fever for 2 days and severe myalgia in lower limbs followed by a skin rush and thrombocytopenia. Results: The diagnosis of the dengue viral infection was confirmed on the basis of the positive serum IgM antibody. Creatine kinase levels persisted elevated after 1 year from diagnosis with minimal complains. Her first assessment revealed muscle weakness, which was proximal and asymmetric in the lower limbs accompanied by mild muscle atrophy of left lower limb. A muscle biopsy of the deltoid showed myopathic changes, including moderate variation in fiber size and necrosis, suggesting a necrotizing myopathy. Protein immunohistochemistry studies showed normal immunoexpression except a diffuse MHC class I over-expression. A genetic panel of Next Generation Sequencing containing ANO5, DYSF, GAA, SGCB, SGCG, CAPN3, FKRP, SGCA, SGCD, and TCAP genes was done and with no mutations found. Conclusion: This report is the first one to describe dengue associated with necrotizing myopathy. We should to think in infection disease in patients presenting persisted creatine kinase levels with almost no symptoms. We also suggest that reviews of creatine levels and muscle biopsy in a large cohort of patients with dengue fever would be necessary to confirm this impression.

PS1Group1-076 / #492EXPRESSION OF DYSTROPHIN ISOFORMS IN NEW DUCHENNE MUSCULAR DYSTROPHY MICE MODEL

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Tatiana Egorova¹, Dmitry Vlodavets², Denis Reshetov³, Evgenia Zotova³, Anna Polikarpova³, Svetlana Vassilieva³, Alexei Deikin¹

¹Core Facility, Institute of Gene Biology RAS, Moscow, RU;²Russian Children Neuromuscular Center, Veltischev Scientific Research Clinical Pediatric Institute, Pirogov Russian National Research Medical University, Moscow, RU;³Research Department, Marlin Biotech LLC, Moscow, RU

Background: New Duchene muscular dystrophy mice model was created in Russia using CRISPR/Cas9 gene editing system. Two sgRNAs targeted to introns 7 and 34 respectively were injected into mice zygotes with Cas9 protein. Cas9 introduces double-strand breaks which are repaired by cell machinery with random indel formation. As a result of microinjections into zygotes 20 mice were born with desired deletion of exons 8-34 (DMDdel8-34). Sequence verification of deletion borders revealed several groups with different mutations. Methods: Three mice representing different deletion borders with 3, 8 and 18 base pair gaps between target sites were used for breeding. For all of them sgRNAs targeted intronic regions and they have same mutations on mRNA level. Third and fourth mice generations after their breeding were analyzed using histology, physiology and molecular biology methods. Results: Here we present some features of the model. New model demonstrates representative dystrophy symptoms on muscle histology such as central nucleation in myofibers, fibrosis and calcinosis formation in striated muscles. Great difference was shown between control (CBA/C57Bl6) and experimental group (DMDdel8-34) in hanging test. Quantitative RT-PCR was used to check dystrophin mRNA presence in knockout mice. It was expected that in this case dystrophin-coding RNA should be destroyed by nonsense-mediated decay because deletion of exons 8-34 leads to frameshift in 35 exon. Surprisingly there was no difference in mRNA expression level between control and experimental groups when using primers to dystrophin exons 1-7. Dystrophin mRNA expression can be explained by alternative splicing. To verify that there is no dystrophin protein expression western blotting assay was performed on primary myoblasts derived from murine model muscles using polyclonal antibodies raised against C-terminus of dystrophin. Absence of full-length (427kDa) dystrophin form was verified but 70kDa band was detected which corresponds to Dp71 dystrophin C-terminal isoform normally expressed in non-muscle tissues such as lung or brain. Therefore, we can suggest the presence of alternative dystrophin isoforms in DMDdel8-34 muscle cells. Conclusion: The finding needs further investigation because any treatment strategy tested on the model require functional restoration of dystrophin. Short dystrophin isoforms with noncanonical expression profile existing in model muscles can occupy dystrophin binding sites on cell membrane. Even in the case of restored expression of proper muscular isoform, functionality of the protein should be investigated.

PS1Group1-077 / #759MYOTONIC DYSTROPHY TYPE 2 AS A MULTISYSTEM DISEASE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Ivo Bozovic¹, Stojan Peric¹, Jovan Pesovic², Bogdan Bjelica¹, Milos Brkusanin², Ivana Basta¹, Ana Marjanovic¹, Marija Brankovic¹, Aleksandra Kacar¹, Dusanka Savic-Pavicevic³, Vidosava Rakocevic-Stojanovic¹

¹Neurology Clinic, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia, Belgrade, RS;²Faculty of biology, Belgrade, RS;³Faculty of Biology, Center for Human Molecular Genetics, University of Belgrade, Belgrade, RS

Background: Myotonic dystrophy type 2 (DM2) is a multisystem disorder, mostly presented with mild but heterogeneous spectrum of symptoms. The aim of this research was to provide detailed sociodemographic, clinical and laboratory data of a large DM2 cohort from the Serbian registry. Methods: In 2008, we started to prospectively enter data of all DM patients. We also retrospectively collected data of patients hospitalized from 1990 until 2008. At the end of 2017, Serbian registry comprised 87 (68%) of 128 genetically confirmed DM2 patients in Serbia, i.e. 1.2 registered cases per 100,000 inhabitants. Results: Female subjects were more prevalent in the registry (63%). The diagnostic delay was 12±11 years and mean age at entry in the Registry was 51±13 years. The most common first symptom in our patients was leg weakness, followed by handgrip myotonia and pain, although some patients presented with cataracts or extrapyramidal syndrome. In 75% of patients lens opacities were present. Severe ECG abnormalities were noted in 8% and pacemaker was implanted in 5% of DM2 subjects. Pulmonary restriction was observed in 10% of DM2 patients. Insulin resistance and diabetes mellitus were frequent in our DM2 cohort (21% and 17%, respectively). Majority of them had hyperlipidemia. Male subjects more frequently had snoring, baldness, sterility and polyneuropathy, while waddling gait and brisk muscle reflexes were more common in females. Conclusion: This registry offers a spectrum of different DM2 features presented in the Serbian population, which could be at service of earlier diagnosis and better follow-up of these patients.

PS1Group1-078 / #672HEART INVOLVEMENT IN MYOTONIC DYSTROPHY TYPE 2

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Bogdan Bjelica¹, Stojan Peric¹, Edita Cvijan¹, Gorana Mandic-Stojmenovic¹, Masa Kovacevic¹, Ksenija Aleksic¹, Jovan Pesovic², Dusanka Savic-Pavicevic², Ivana Basta¹, Dragana Lavrnic¹, Vidosava Rakocevic-Stojanovic¹

¹Neurology Clinic, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia, Belgrade, RS;²Faculty of Biology, Center for Human Molecular Genetics, University of Belgrade, Belgrade, RS

Background: Myotonic dystrophy type 2 (DM2) is a slowly progressive, autosomal-dominant disease. This is a multisystemic disorder that affects the heart, which may be one of the main causes of morbidity and mortality in DM2. The aim of this study was to define cardiac impairments in patients with DM2 and its association with sociodemographic and clinical features of the patients. Methods: This retrospective study comprised 62 patients with genetically confirmed DM2, hospitalized at the Neurology Clinic, Clinical Center of Serbia, from 2013 until 2018. All patients were analyzed by electrocardiography (ECG) and transthoracic echocardiography. Results: Hypertension was observed in 42% of DM2 patients. One fifth of the DM2 patients had bradycardia while other conduction and rhythm impairments were rare, including left bundle branch block (3%), ventricular extrasystoles (5%), and supraventricular extrasystoles (2%). Only one patient had implanted pacemaker because of the first degree AV block and incomplete left bundle branch block. Valve fibrosis was common: aortic 64%, tricuspid 30%, and mitral 19%. Mitral regurgitation was seen in 27% of DM2 subjects. Diastolic dysfunction was observed in 44% of patients, while systolic dysfunction was found in 4%. Cardiomyopathy was observed in 18% of patients, of whom three fourths had dilated type. Conclusion: Cardiac conduction and rhythm defects were rare in DM2, but sometimes even pacemaker implantation is needed. Diastolic dysfunction of the left ventricle was common. This suggest that regular ECG and echocardiography screening is needed in DM2. We suppose that early treatment may prevent development of cardiac complications and early death.

PS1Group1-079 / #673VARIANT REPEATS STABILIZE EXPANSION AND MODIFY AGE AT ONSET IN MYTONIC DYSTROPHY TYPE 1

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Jovan Pesovic¹, Stojan Peric², Milos Brkusanin¹, Goran Brajuskovic¹, Vidosava Rakocevic-Stojanovic³, Dusanka Savic-Pavicevic¹

¹Faculty of biology, Belgrade, RS;²Neurology Clinic, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia, Belgrade, RS;³Neurology Clinic, Belgrade, RS

Background: Myotonic dystrophy type 1 (DM1) is a variable multisystem disease with age at onset ranged from in utero to late decades. Underlying mutation is the expansion of CTG repeats at the 3¢ untranslated region of DMPK gene, characterized by a pronounced somatic instability biased towards further expansions over time. Expansion size and level of somatic instability explain ~60% of variation in age at onset. Variant repeats at DMPK expansions, observed in 3-5% of patients, have been associated with later age at onset. We aimed to study an effect of variant repeats on dynamics of somatic instability at DMPK locus and age at onset in seven patients. Methods: Four patients with pure CTG repeats served as controls. Repeat-primed PCR profiles and Sanger sequencing indicated the stable structure of different patterns of CCG (CCGCTG hexamers, small and large CCG blocks) and CTC repeats in blood cells over time ranging the period of two and a half to four years. We performed single cell small-pool PCR to size approximately 5000 individual alleles in analysed samples and thus quantify somatic instability of variant DMPK expansions as whole tracks. Results: By using the published correlation models and data set of individually sized alleles in the reference group of patients [Martorel et al. 1998; Morales et al. 2012] we obtained the following results: (1) a lower level of somatic instability of variant expansions then expected based on the expansion size and age at sampling (V=0, p=0.016 for the first time point and V=0, p=0.008 for the second time point), and a less mean residual variation in somatic instability not accounted for by the expansion size and age at sampling in patients with variant expansions than in the reference group (W=871, p=2.2e^-4for the first time point and W=1004, p=6.135e^-5 for the second time point); (2) a lower expansion increment over time than expected based on the expansion size and time interval between sampling (V=0, p=0.016); (3) a less mean residual variation in age at onset not accounted for by the expansion size and level of somatic instability in patients with variant expansions than in the reference group (W=172, p=0.04 for the first time point and W=192, p=0.02 for the second time point). Conclusion: Our results provide a firm evidence for a general stabilizing effect of different patterns of variant repasts at the DMPK locus in blood cells. This feature of variant repeats most likely positively modulate age at onset of DM1 symptoms and, therefore, has the clinical importance in terms of disease course prediction and new potential therapeutic approaches.

PS1Group1-080 / #674FEATURES OF THE SERBIAN COHORT OF PATIENTS WITH CALPAINOPATHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Stojan Peric¹, Ana Kosac¹, Marija Brankovic¹, Ana Marjanovic¹, Bojan Banko², Sanja Milenkovic³, Milena Jankovic¹, Dragana Lavrnic¹, Ruzica Maksimovic², Vedrana Milic Rasic⁴, Vidosava Rakocevic-Stojanovic¹

¹Neurology Clinic, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia, Belgrade, RS;²Center for Radiology and Magnetic Resonance Imaging, Clinical Center of Serbia, Belgrade, Serbia, Belgrade, RS;³Department of Pathology, Clinical Hospital Centre Zemun, Belgrade, Serbia, Belgrade, RS;⁴Clinic for Neurology and Psychiatry for Children and Youth, Belgrade, Serbia, Belgrade, RS

Background: In majority of countries the most common form of limb-girdle muscular dystrophy is a type 2A (LGMD2A) caused by mutation in CAPN3 gene coding calpain 3 protein. Aim of this research was to analyze genetic and phenotypic features of Serbian patients with calpainopathy. Methods: This study comprised 19 patients (42% males) from 18 families with genetically confirmed LGMD2A. Here we describe their clinical and laboratory features, magnetic resonance imaging (MRI) of lower legs and histopathological (HP) findings in muscle biopsy samples. Results: Eighteen (95%) patients in this cohort had c.550delA mutation, with nine being homozygous. The age at onset ranged between 7 and 40 years (median 14 years). Only one patient had disease onset after age of 22 (at age of 40). Symptoms usually started as a proximal leg weakness and in three (16%) patients as a proximal arm weakness. Majority of patients were symptomatic at time of diagnosis, but in two of them the disease was discovered during analysis of asymptomatic hyperCKemia, while one was diagnosed as an asymptomatic family member. Serum CK levels were elevated in all patients from about four to 100 times higher than normal. EMG showed a myopathic pattern in all subjects. Mean age at the last examination was 25 ± 10 years with mean disease duration of 12 ± 5 years. Proximal leg and (to lesser degree) proximal arm muscle wasting and weakness was the most prominent feature. Two patients started to use wheelchair at the age of 19 and 27, one used a walker and one cane. Scapular winging was present in 16 (84%) patients. Ankle contractures were present in all CAPN3 subjects, while three (16%) also had elbow contractures. Muscle hypertrophy was detected in ten (53%) patients: seven had calf, two proximal leg and one lower arm hypertrophy. The facial and bulbar muscles were not affected. None of the patients had significant conduction defects nor cardiomyopathy. Four (21%) patients exhibited spirometry restriction (FVC<90%). Muscle MRI showed more severe affection of the proximal leg muscles, with triceps surae muscle being the most affected among distal muscles. Muscle HP showed dystrophic pattern with eosinophilic infiltrations in some patients. Conclusion: Calpainopathy is a common form of LGMD in Serbia and it has specific clinical, laboratory, MRI and HP features.

PS1Group1-081 / #408MALIGNANT HYPERTHERMIA AND MH-LIKE REACTIONS IN NEUROMUSCULAR DISEASES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Bram De Wel¹, Kristl G. Claeys²

¹Neurology, University Hospitals Leuven And Ku Leuven, Leuven, BE;²University Hospitals Leuven And Ku Leuven, Leuven, BE

Background: Malignant Hyperthermia (MH) is a life-threatening hypermetabolic reaction in susceptible patients caused by an excessive calcium release from the sarcoplasmic reticulum in skeletal muscles in response to primarily volatile halogenated anesthetics and the depolarizing muscle relaxant succinylcholine. Mutations in the gene encoding the ryanodine receptor 1 (RYR1) are the most frequently identified underlying genetic defects, but mutations in other genes have also been described such as CACNA1S, STAC3, SCN4A and CACNL2A. Over the years, case reports have linked an increasing number of muscular phenotypes to MH susceptibility. This can cause uncertainty in the clinical neurological practice, sometimes leading to excessive labeling of patients as MH susceptible, or even worse, missing the diagnosis. MH-like reactions in response to succinylcholine (and possibly volatile anesthetics) also exist and are associated with severe hyperkalemia and rhabdomyolysis, but are thought to be of a different etiology than true MH. The aim of our study is to explore all muscular disorders that can possibly be linked with MH or MH-like reactions and to suggest an appropriate approach to interpret the accompanying risks. Methods: We performed a systematic and comprehensive search using Pubmed for studies published from the 1960’s up to January 2018. Search terms such as ‘Malignant Hyperthermia’, ‘Malignant Hyperthermia susceptibility’, ‘Malignant Hyperthermia genetics’ and ‘RYR1 myopathies’ were used. We included case reports, reviews and retrospective cohort studies. In addition, we incorporated data published on the ‘European Malignant Hyperthermia Group’ website. Results: Throughout the literature (n = 1012 papers), all patients with myopathies caused by RYR1 mutations are assumed MH susceptible, unless an in vitro contracture test has proven otherwise. This is a good practical assumption, although theoretically it is estimated that only about 30% of these patients are actually MH susceptible. The spectrum of myopathies and clinical syndromes linked to MH through RYR1 mutations now includes - amongst others - central core disease, multiminicore myopathy, congenital myopathy with cores and rods, King-Denborough syndrome, centronuclear myopathy, and nemaline myopathy. In addition, idiopathic hyperCKemia and exertional rhabdomyolysis are also part of the RYR1-disease spectrum. Mutations in CACNA1S mainly cause periodic paralysis and mutations in STAC3 are known to be the cause of Native American myopathy. Finally, there are muscle diseases that were long presumed to be at an increased risk of developing MH, such as Myotonic Dystrophy type I, that are now known to be at an equal risk of developing MH in response to volatile anesthetics compared to the general population. However, succinylcholine should still be avoided in these patients as there can occur unpredictable muscle contractures after administration and sometimes even an exaggerated hyperkalemic response (i.e. MH-like reaction). The muscular dystrophies such as Duchenne and Becker muscular dystrophy can also be associated with a MH-like reaction to succinylcholine. Conclusion: We provide a summary of current evidence linking certain neuromuscular diseases to MH or MH-like reactions peri-operatively. Our study results in a guide for the practicing clinician, in order to know when peri-operative precautions need to be taken or advised in patients with diverse muscular diseases.

PS1Group1-082 / #493ORO-PHARYNGEAL DYSPHAGIA IN MYOTONIC DYSTROPHY TYPE 1 (DM1): IDENTIFICATION OF SENSORY CHANGES IMPACTING SWALLOWING FUNCTION

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Jodi E. Allen¹, Chris Turner²

¹Therapy And Rehabilitation, The National Hospital for Neurology and Neurosurgery , 3BG, GB;²Institute Of Neurology, University College London Hospital MRC Centre for Neuromuscular Diseases, BG, GB

Background: Aspiration pneumonia is the leading cause of mortality in adults living with Myotonic Dystrophy Type 1 (DM1). Swallowing disturbance (oro-pharyngeal dysphagia, OPD) contributes to this profile of recurrent respiratory infection, hospital admission and premature death. Patients with DM1 rarely report alterations in their swallowing despite its high prevalence. It is currently unclear as to why this lack of complaint occurs but absence of patient report does have implications for identification of OPD and its management. This study explored the possibility of sensory alterations in DM1 as a reason for poor patient reporting by studying patient responses to post-swallow residues, aspiration and/or penetration which normally provoke an overt set of clinical signs and symptoms. Methods: A retrospective review of swallowing reports was undertaken for all adult patients with genetically confirmed DM1 referred for instrumental evaluation of swallowing via Videofluoroscopy (VFS) or Fibreoptic Endoscopic Evaluation of Swallowing (FEES) from a tertiary neuromuscular centre between May 2015-February 2018. Reports were analysed for presence of pooled secretions (FEES only), post swallow residues, awareness of residues and presence and response to aspiration and penetration. Results: A total of 39 VFS reports and 8 FEES reports were reviewed. Videofluoroscopy: 38/39 (97%) patients had post-swallow residues in the pharynx; 9 (24%) were not aware, 21 (55%) were partially aware, 7 (18%) had good awareness and 1 was not reported. 6/39 (15%) aspirated, 5 showed no response. 12/39 (31%) had food and/or drink penetrating the airway, 9 showed no response. FEES: 7/8 (88%) had pooled saliva at rest, 5 of whom had secretions in the laryngeal vestibule. 8/8 (100%) had post-swallow residues; 2 showed no awareness, 4 showed partial awareness, 2 were not reported. 2/8 aspirated, both without response. 5/8 penetrated without response. Conclusion: Post-swallow residues occur frequently as part of the OPD profile in DM1. In this study, over three quarters of patients with residues were not fully aware of them. Reduced awareness of these residues plus absence of response to aspirated and penetrated material strongly suggests an underlying sensory deficit. Altered sensation has not previously been explored in DM1 but could provide one explanation for poor reporting of OPD symptoms. Altered sensation is of clinical significance in both the identification and management of OPD. Reliance on patient report, in the presence of sensory deficits, is likely to lead to delayed or inaccurate diagnosis; putting patients at risk of unexpected chest infections and unplanned hospital admissions. Effective OPD management frequently relies on good sensory awareness in the pharynx and larynx. In the absence of this, patients may not recognise the benefits of swallow management advice, nor self-monitor its effectiveness. This is the first step in better understanding non-motor changes in OPD associated with DM1. Further research will explore the nature and aetiology of these sensory changes as well as relationships between OPD and other clinical markers with the aim of identifying more reliable tools for detection of OPD in this population. In the meantime clinicians should exercise caution when relying solely on patient report in the detection and management of swallowing problems.

PS1Group1-083 / #609HMGCR-MYOPATHY. A RARE BUT STILL A SEVERE DISEASE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Josep M. Grau¹, Pedro J. Moreno¹, Sergio Prieto-González¹, Albert Selva-O’Callaghan², Odette Viñas³, José C. Milisenda¹

¹Internal Medicine, Hospital Clinic de Barcelona, Barcelona, ES;²Internal Medicine, Hospital Vall d’Hebrón, Barcelona, ES;³Immunology, Hospital Clinic de Barcelona, Barcelona, ES

Background: The term HMGCR-myopathy has been recently coined in order to define the cases presenting with subacute proximal muscle weakness, high values of CK, necrotizing myopathy with minimal or no inflammation in muscle biopsy and the detection of the anti HMGCR antibodies. Nevertheless the clinical picture, associated manifestations as well as its management remain controversial. ­Methods: Our aim was to present our series of HMGR-myopathy patients observed in a single Center at the Muscle Research Group In the Hospital Clínic of Barcelona. Results: Fourteen cases were identified. They came from a series of 1,200 muscle biopsies in the past 10 years. Relevant information is expressed in table 1. Table 1. Patient’s relevant data. CMP: cardiomyopathy; PR:partial reponse: CR: complete response. Conclusion: After a median follow-up of 38,7 months, only 4 patients are in complete remission without any immunosuppressive drug. Fifty percent required IV Ig and 30% RTX for their refractority to prednisone plus an immunosuppressive agent such as MTX, AZA or TK. All patients but one were exposed to statins. Of note was the severe dysphagia in two patients and the simultaneous and reversible cardiomyopathy in other two cases. Although necrotizing immunomediated myopathy was the pathological diagnosis in 12 cases, one case exhibited only a few regenerating fibers (untreated patient) and typical features of dermatomyositis were found in another case. The poorest outcome was observed in younger patients.

PS1Group1-084 / #639VALUE OF DIAGNOSTIC ALGORITHM IN  ASYMPTOMATIC HYPER-CK-EMIA AND ITERATIVE RHABDOMYOLYSIS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Josep M. Grau¹, José C. Milisenda², Francesc Cardellach², Judith García³

¹Internal Medicine, Hospital Clínic, Barcelona, ES;²Internal Medicine, Hospital Clinic de Barcelona, Barcelona, ES;³Biochemistry, Hospital Clinic de Barcelona, Barcelona, ES

Background: Asymptomatic HiperCkemia (AHCK-emia) as well as iterative rhabdomyolysis (IR) still represent a diagnostic challenge. After the comprobation (three different samples, a week apart) of the raised CK values, and after rulling out the common causes of raised CK (strenuous exercise, illicit drugs, alcoholism, hypothyroidism, acute viral infection, seizures, surgery, trauma, dyselectrolitemia and apnea-hypopnea syndromes, among others) we propose a diagnostic algorithm. Methods: The first step in the algorithm includes a simultaneous triple approach. First the Ischemic forearm test (grip test), second, dried blood spot for excluding Pompe disease and third acylcarnitines profile (beta-oxidative dysfunctions). If the diagnosis is not yet reached, the next steps include whole-body muscle MRI and muscle biopsy, with genetic studies, mitochondrial respiratory chain activity and biochemical studies in fibroblasts culture, when indicated. Results: From January 2016 to December 2017, 25 well-selected patients were included for either AHCK-emia or IR. After sequential tests as indicated a definite diagnosis was obtained in 13 cases. The diagnosis were as follows: muscle dystrophies 5, glucogenosis 3, acylcoA multiple dehydrogenase deficiency 2, congenital myopathies 2 and myoadenilate deficiency 1. In the remaining 12 cases, all the tests, including genetics were normal. Conclusion: The proposed algorithm allows the diagnosis in only 50% of the cases. Of note is that in near 50% of the cases a definite diagnosis was not achieved.

PS1Group1-085 / #760NEXT GENERATION SEQUENCING OF DYSTROPHIN GENE IN A COHORT OF NON-DELETION/DUPLICATION DMD/BMD EGYPTIAN PATIENTS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Nagia Fahmy¹, Nasser Elhawary², Nermin Elsayed¹, Sabin Schröder³, Martin Werber³

¹Ain Shams University, Ain Shams University, Cairo, EG;²Umm El-qura University, Umm El-Qura University, Makkah, SA;³Centogene Ag, Centogene AG, Rostock, DE

Background: The diagnosis of Duchenne/Becker muscular Dystrophy (DMD/BMD) is still challenging owing to the large size of the gene and the occurrence of many mutations. The clinical phenotype, X-linked inheritance and high creatine kinase (CK) serum level are the corner stones in the diagnosis of DMD/BMD patients. The confirmed genetic diagnosis and accurate detection of the type and site of mutation of dystrophin gene became mandatory for the recent therapies and genetic interventions. Methods: We studied 32 patients with DMD/BMD phenotype (including 8 families with 2 affected members of each family) that had no deletion/duplication of MLPA of dystrophin gene. Patients were selected from those attending the outpatient myology and Neurology clinics, Neuromuscular unit, Faculty of Medicine, Ain Shams University, Cairo, Egypt. They had laboratory assessment included serum creatine kinase, nerve conduction and electromyography of both upper and lower limbs, Echocardiography and Multiplex Ligation-dependent Probe Amplification (MLPA) of dystrophin gene to diagnose large deletion/duplication. Muscle biopsy with histochemistry and immunohistochemistry was done to 6 patients and other patients preferred to continue further genetic study without biopsy. The dystrophin gene was analyzed in Centogene laboratories by PCR and next generation sequencing of DNA strands of the entire coding region and the highly conserved exon-intron splice junctions. Results: We found 11 patients with non-sense mutation (four of them were brothers; three of these mutations were not described before). A missense variant was detected in two brothers that were not described before, Small deletions were present in 8 patients, four of them were not described before and a patient with small duplication that was not described before. We found one patient with a hemizygous deletion encompassing intron 11 that was not covered by MLPA and another patient with a pathogenic variant predicted to disrupt the highly conserved donor splice site of exon 55. Another patient showed failure of sequencing exons 48-50, so MLPA was repeated and showed deletion of those exons. No clinically relevant variants were found in 7 patients, 3 of them had the BMD phenotype and diagnosed by immunohistochemistry and western blot study. Conclusion: Next generation sequencing of dystrophin gene is mandatory to all DMD/BMD patients with no deletion/duplication of MLPA. Muscle biopsy and immunohistochemistry of dystrophin protein and dystrophin associated proteins is still highly recommended before doing detailed genetic study. RNA sequencing is needed for those patients who are pathologically proved to have dystrophinopathy and their DNA sequencing didn’t show any mutations.

PS1Group1-086 / #823NATURAL HISTORY OF DISEASE-RELATED COMPLICATIONS IN PATIENTS WITH DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Jessie Lynch, Katherine Tsai, John Lu, Chris Mix, Andre M. York

Sarepta Therapeutics Inc, Cambridge, MA, US

Background: Duchenne muscular dystrophy (DMD) is a rare, X-linked recessive, fatal disorder in which DMD gene mutations inhibit production of dystrophin, leading to progressive muscle weakness. A current therapeutic approach for DMD involves use of phosphorodiamidate morpholino oligomers (PMOs) for exon skipping. These neutrally charged oligonucleotides target specific exons within the DMD pre-messenger ribonucleic acid (mRNA), induce skipping and exclusion of the targeted exon, and restore the DMD mRNA reading frame. Collectively, these actions facilitate translation and production of an internally shortened dystrophin protein. Clinical trials are ongoing to evaluate PMOs for use in DMD. Individuals diagnosed with DMD develop numerous complications throughout disease progression. Within the clinical trial setting, it is critical to differentiate complications associated with the disease and use of concomitant medications, such as corticosteroids, from adverse events potentially related to treatment. Methods: A review of the published literature was conducted to identify relevant articles evaluating the natural history of disease-related complications in DMD patients. Results: A majority of the literature focused on complications representing the two primary causes of death in DMD: cardiac failure, with cardiomyopathy as a significant factor, and respiratory failure, which stems from functional declines in the diaphragm and other respiratory muscles. The prevalence of cardiomyopathy (shortening fraction <28% and/or ejection fraction <55%) increased with age and disease progression, impacting 5% of patients aged 0–5 years, 38% of patients aged 14–17 years, and >60% of patients aged ≥18 years. Age was an important predictor of cardiomyopathy presence, regardless of corticosteroid use. Similarly, impairments in respiratory function also worsened with DMD progression; the majority of data showed a linear decline of ≥5% annually in percent predicted forced vital capacity (FVC%p). In some studies, decline in pulmonary function was largely unaffected by corticosteroid treatment regimen or ambulatory status. Clinical evidence suggested that DMD patients were also prone to numerous other complications, including nephrolithiasis, low bone mass density, rhabdomyolysis, and comorbid psychiatric conditions. In a logistic regression analysis, DMD was an independent risk factor for development of symptomatic nephrolithiasis (odds ratio, 14.26 vs nonambulatory, non-DMD control patients). Increased risk of low bone mass density or fracture was frequently reported and related to progressive muscle weakness, inflammatory cytokine release, continuous corticosteroid regimens, immobility, and vitamin D insufficiency, among other factors. Rhabdomyolysis is a less common but possibly fatal complication that may result from use of specific types of anesthesia in DMD patients. However, unprompted, acute episodes of rhabdomyolysis also occur in DMD patients, and many clinicians perceive this complication as a component. Finally, DMD progression was linked to comorbid psychopathologies, including intellectual disability, autistic spectrum disorder, attention deficit hyperactivity disorder, and behavioral problems. Conclusion: In conclusion, numerous comorbid conditions parallel DMD disease progression. Thorough understanding and awareness of these disease-related comorbidities is critical to differentiation from potential side effects of disease-modifying therapies, especially in the context of clinical investigation.

PS1Group1-087 / #790GOLODIRSEN LEADS TO SARCOLEMMAL DYSTROPHIN EXPRESSION IN PATIENTS WITH GENETIC MUTATIONS AMENABLE TO EXON 53 SKIPPING

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Francesco Muntoni¹, Diane Frank², Jennifer Morgan³, Joana Domingos³, Frederick Schnell², J. G. Dickson⁴, Michela Guglieri⁵, Andreea Seferian⁶, Mauro Monforte⁷, Laurent Servais⁶, Volker Straub⁸, Eugenio Mercuri⁷, Skip-Nmd Study Group⁹

¹Dubowitz Neuromuscular Unit, UCL Great Ormond Street Institute of Child Health, London, GB;²Sarepta Therapeutics Inc, Cambridge, MA, US;³University College London, London, GB;⁴Royal Holloway, University of London, London, GB;⁵ewcastle University and Royal Victoria Infirmary Hospital, Newcastle upon Tyne, GB;⁶Institute of Myology, Paris, FR;⁷Catholic University of the Sacred Heart, Rome, IT;⁸Newcastle University, Institute of Genetic Medicine, Newcastle Upon Tyne, GB;⁹SKIP-NMD Study Group, Cambridge, MA, US

Background: Golodirsen (formerly SRP-4053) is a phosphorodiamidate morpholino oligomer (PMO) that binds to dystrophin mRNA, and targets and excludes exon 53 during mRNA processing, facilitating the production of internally shortened dystrophin protein. A 2-part, first-in-human, multicenter trial (ClinicalTrials.gov Identifier: NCT02310906) is evaluating the safety, tolerability, and efficacy of golodirsen in patients with Duchenne muscular dystrophy (DMD) and genetic mutations amenable to exon 53 skipping. We report dystrophin production, exon 53 skipping, and dystrophin cellular localization at baseline and after 48 weeks of treatment with golodirsen. Methods: Part 1 of this trial, which has been completed, included a randomized, double-blind, placebo-controlled, 12-week dose escalation of golodirsen. Part 2, which is ongoing, is a 168-week open-label evaluation of once-weekly golodirsen 30 mg/kg. In preplanned interim analyses, eligible patients had paired muscle biopsies of the biceps brachii at baseline (part 1) and at Week 48 of once-weekly treatment with golodirsen (part 2). Patients newly enrolled in part 2 had the same biopsies at baseline of part 2 and at Week 48. A validated Western blot method quantified dystrophin production (primary biological end point). Exon 53 skipping was evaluated using reverse transcription polymerase chain reaction (RT-PCR). Immunohistochemistry assessed dystrophin localization and sarcolemma fiber intensity. Results: Biopsies were obtained and analyzed from all 25 patients. Mean percent of normal dystrophin protein increased from 0.095% at baseline to 1.019% at Week 48, a significant mean change of +0.924% (P<0.001). Muscle biopsy samples from all patients displayed a significant increase from baseline in exon 53 skipping via RT-PCR at Week 48 (P<0.001), demonstrating the intended mechanism of action. A positive correlation between exon 53 skipping and de novo dystrophin production was observed (Spearman r=0.500; P=0.011). Mean fiber intensity analysis showed a significant increase from baseline in de novo dystrophin production (P<0.001) and confirmed correct dystrophin localization to the sarcolemma. Conclusion: Increased mean dystrophin protein production, exon 53 skipping, and correct sarcolemmal localization of dystrophin were observed in muscle biopsies from golodirsen-treated patients. Golodirsen is the second PMO shown to increase dystrophin protein expression and demonstrate membrane localization following initiation of exon skipping. These findings add to the growing body of evidence of a role for the PMO technology platform in the treatment of DMD.

PS1Group1-088 / #945POMPE DISEASE IN FRANCE: MOLECULAR FEATURES, EPIDEMIOLOGY AND CLINICAL CORRELATIONS FROM A FOURTY-FIVE YEAR NATIONWIDE STUDY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Claudio Semplicini¹, Pascaline Letard², Marie De Antonio³, Nadjib Taouagh⁴, Barbara Perniconi⁴, Françoise Bouhour⁵, Andoni Echaniz-Laguna⁶, David Orlikowski⁷, Sabrina Sacconi⁸, Emmanuelle Salort-Campana⁹, Guilhem Solé¹⁰, Fabien Zagnoli¹¹, Dalil Hamroun¹², Roseline Froissart¹³, Catherine Caillaud¹⁴, Pascal Laforet¹⁵

¹University of Padova - Azienda Ospedaliera di Padova, Padova, IT;²Laboratoire de Biochimie Métabolomique et Protéomique, Hôpital Necker Enfants Malades, Paris, France, FR;³Centre de référence des maladies neuromusculaires, CHU Henri-Mondor, AP-HP, Créteil, France., Paris, FR;⁴Institut de Myologie, Hôpital La Pitié-Salpétrière, AP-HP, Paris, France, Paris, FR;⁵Service ENMG et pathologies neuromusculaires, Hôpital Neurologique Pierre Wertheimer, Hospices Civils de Lyon, Lyon, FR;⁶Department of Neurology, University Hospital Strasbourg, Strasbourg, FR;⁷Pôle de ventilation à domicile, AP-HP, Hôpital Raymond Poincaré,, Garches, FR;⁸Centre de référence des Maladies Neuromusculaires, Hôpital Archet, France. CNRS UMR7277, INSERM U1091, IBV - Institute of Biology Valrose, UNS Université Nice Sophia-Antipolis, Faculté de Médecine, Nice, FR;⁹Reference Center for Neuromuscular Diseases and ALS, La Timone University Hospital, Aix-Marseille University, Marseille, FR;¹⁰Department of Neurology, Nerve-Muscle Unit, CHU Bordeaux (Pellegrin Hospital), University of Bordeaux, Bordeaux, FR;¹¹CHRU Cavale-Blanche,, Brest, FR;¹²Direction de la Recherche et de l’Innovation, CHRU de Montpellier, Hôpital Arnaud de Villeneuve, Montpellier, FR;¹³Service de Biochimie et Biologie Moléculaire, Centre de Biologie et Pathologie Est, Hospices civils de Lyon, Lyon, FR;¹⁴INSERM U1151, Institut Necker Enfants Malades, and Université Paris Descartes, Sorbonne Paris Cité, Paris, FR;¹⁵Centre de référence des maladies neuromusculaires Nord-Est-Ile de France, Service de Neurologie, CHU Raymond Poincaré, AP-HP, Garches, France. INSERM U1179, END-ICAP, équipe Biothérapies des Maladies du Système Neuromusculaire, Université Versailles Saint, Garches, FR

Background: Pompe disease (PD) is an autosomal-recessive disorder caused by the deficiency of the lysosomal enzyme acid a-glucosidase (GAA) due to mutations in GAA gene. The clinical spectrum of disease ranges from rapidly fatal multisystemic disorder (classical PD) to a milder adult onset myopathy (late onset PD). There are no straightforward correlations between clinical features, rate of enzymatic reduction and type of mutations. Methods: Aim of the study was to identify all patients diagnosed with non classical PD in France since 1970s, in order to characterize molecular diagnoses and clinical features in a large nationwide study. This was possible by collecting data from the two main French biochemical laboratories (Paris and Lyon) and from the French Pompe registry, that includes since 2004 virtually all French PD patients in a structured long-term observational study. Results: We included 246 late onset PD patients diagnosed since 1972 (130F, 116M; mean age at diagnosis 43.1+17.5 years). Eighty-three different variants were identified, spread all over the sequence and including all types of mutations, and 28 (34%) were novel. The common c.-32-13T>G mutation was detected in 151/170 index cases (89%). Other recurrent mutations included deletion exon 18 (7.5%), c.1927G>A, p.Gly643Arg (3.7%), c.655G>A, p.Gly219Arg (2.8%) and the small deletion c.525del, p.Glu176fs*15 (2.5%). The incidence of non-classic PD in France could be estimated around 1/80,000. Correlations between genotype and age at disease onset were weak. Patients with IVS1 mutation (n=131) presented a later onset compared to 18 non-IVS1 patients (36.2 ±13,9 vs 24,7 ± 14,8 ; p <0,01). However, patients presenting identical genotype could manifest at very different ages. Conclusion: In conclusion, in this study we present the molecular and epidemiologic data from the largest described cohort of non classic PD patients, in a nationwide study covering more than 40 years of this challenging diagnosis. The high molecular and clinical variability we described suggest the need of more population studies to identify potential disease modifiers.

PS1Group1-089 / #987A SPANISH MYOTONIC DYSTROPHY TYPE I FAMILY CARRYING INTERRUPTIONS SHOWING A MILDER AND ATYPICAL PHENOTYPE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Emma A. Koehorst¹, Alfonsina Ballester-Lopez², Miriam Almendrote³, Alba R. Fransi³, Alicia Martínez-Piñeiro³, Giuseppe Lucente³, Ian Linares³, Judith Nuñez³, Nicolau Guanyabens⁴, Alejandro Lucia⁵, Antoni Cano⁵, Teresa Casadevall⁶, Agustí Rodríguez-Palmero³, Laura Monlleó-Neila⁷, Guillem Pintos-Morell³, Jaume Coll-Cantí³, Gisela Nogales-Gadea³

¹Neuromuscular And Neuropaediatrics Group, IGTP Research Center, Badalona, ES;²Centro De Investigación Biomédica En Red De Enfermedades Raras (ciberer), Instituto de Salud Carlos III, Madrid, ES;³Neuromuscular And Neuropaediatrics Group, IGTP research center, Badalona, ES;⁴Neurology Unit, Neuroscience Department, Hospital de Mataró, Barcelona, ES;⁵Universidad Europea, Instituto de Investigación Hospital 12 de Octubre (i+12), Madrid, ES;⁶Neuromuscular Unit. Neurology Service. Neuroscience Department, Hospital Comarcal Sant Jaume de Calella, Barcelona, ES;⁷Neuropediatric Unit. Pediatric Service., Hospital Universitari Germans Trias i Pujol, Barcelona, ES

Background: In recent years, patients with Myotonic Dystrophy type I (DM1) carrying variant repeat patterns in the CTG expansion, have been described. The phenotypical consequences of the interrupted CTG expansion are still highly controversial. The variant repeat patterns have been associated with a complex co-segregated neurological phenotype, including an intermediate Charcot-Marie-Tooth neuropathy, deafness and encephalopathy. While others have found a milder phenotype with a later age of onset, absence of muscle atrophy and CNS involvement or an atypical phenotype with symptoms more resembling Myotonic Dystrophy type II. The number of DM1 patients described with these interruptions is low, with an estimated prevalence of 3-5%. In this study, a cohort of 50 Spanish DM1 patients has been analyzed with the aim of finding new patients carrying interruptions and determining their clinical phenotypes. Methods: Blood DNA was obtained from the participants and triplet-primed PCR (at the 5’ and 3’ sites), Acil digestion and sequencing was used to determine the presence of these interruptions and the type of interruption present (CCG, CTC or GGC). A patients’ registry was built, containing their clinical information. Results: Out of our fifty DM1 patients, four patients were found to have CCG interruptions in the 3’ end of the CTG expansion. Our clinical database revealed that these patients belong to the same family, in which patient 1, 2 and 3 are sisters, who paternally inherited the disease, and patient 4 is the son of patient 3. Mother and son showed the exact same interruption pattern, while the other 2 sisters both had a different interruption pattern. The male interrupted patient (P4, aged 37 years old) was completely asymptomatic upon clinical examination, despite the 108 CTG progenitor allele. The 3 sisters showed most of the typical features of DM1, although predominant distal weakness was absent. The most remarkable thing is that in the 3 sisters’ symptoms started at a later age (>50 y.o.), classifying them as late-onset DM1, while their symptoms resemble more of a classic/adult phenotype. Conclusion: Here, we report the presence of four interrupted cases in a cohort of 50 DM1 patients, with a prevalence of 3.4 % in our DM1 families. Inheritability of the interruption pattern was shown in our cohort, with an exact replica on maternal transmission. Our study contributes to the observation of a milder and/or atypical clinical phenotype of variant repeat carrying DM1 patients, with a later age of onset than expected and predominantly proximal weakness. The latter resembles more a DM2 phenotype.

PS1Group1-090 / #977MERRF CLASSIFICATION: IMPLICATIONS FOR DIAGNOSIS, AND CLINICAL TRIALS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Josef Finsterer¹, Sinda Zarrouk-Mahjoub², John M. Shoffner³

¹Krankenanstalt Rudolfstiftung, Vienna, AT;²Pasteur Institute Of Tunis, University of Tunis El Manar and Genomics Platform, Tunis, TN;³Molecular Genetics, Neurology, Biochemical Genetics, Atlanta, US

Background: Given the etiologic heterogeneity of disease classification using clinical phenomenology, we employed contemporary criteria to classify variants associated with myoclonic epilepsy with ragged-red fibers (MERRF) syndrome and to assess the strength of evidence of gene-disease associations. Standardized approaches are used to clarify the definition of MERRF which is essential for patient diagnosis, patient classification, and clinical trial design. Methods: Systematic literature and database search with application of standardized assessment of gene-disease relationships using modified Smith criteria and of variants reported to be associated with MERRF using modified Yarham criteria. Results: Review of available evidence supports a gene-disease association for two MT-tRNAs and for POLG. Using modified Smith criteria, definitive evidence of a MERRF gene-disease association is identified for MT-TK. Strong evidence gene-disease evidence is present for MT-TL1 and POLG. Functional assays that directly associate variants with oxidative phosphorylation impairment were critical to mtDNA variant classification. In silico analysis was of limited utility to the assessment of individual MT-tRNA variants. Using contemporary classification criteria, several mtDNA variants previously reported as pathogenic/possibly pathogenic are reclassified as neutral variants. Conclusion: MERRF is primarily a MT-TK disease with pathogenic variants in this gene accounting for ~90% of MERRF cases. Although MERRF is phenotypically and genotypically heterogeneous, myoclonic epilepsy is the clinical feature that distinguishes MERRF from other categories of mitochondrial disorders. Given its low frequency in mitochondrial disorders, myoclonic epilepsy is not explained simply by an impairment of cellular energetics. Although MERRF phenocopies can occur in other genes, additional data is needed to establish a MERRF disease-gene association. This approach to MERRF emphasizes standardized classification rather than clinical phenomenology, thus improving patient diagnosis and clinical trials design.

PS1Group1-091 / #978MITOCHONDRIAL MULTI-ORGAN DISORDER SYNDROME SCORE GENERATED FROM DEFINITE MITOCHONDRIAL DISORDERS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Josef Finsterer¹, Sinda Zarrouk-Mahjoub²

¹Krankenanstalt Rudolfstiftung, Vienna, AT;²Pasteur Institute Of Tunis, University of Tunis El Manar and Genomics Platform, Tunis, TN

Background: Mitochondrial disorders(MIDs) frequently present as mitochondrial multi-organ disorder syndrome(MIMODS) already at onset or evolve into MIMODS during the course. This study aimed to find which are the organs/tissues most frequently affected in MIMODS, which are the most frequent abnormalities within an affected organ, if there are typical MIMODS patterns, and to generate a MIMODS-score to assess the diagnostic probability for a MID. Methods: Retrospective evaluation of clinical, biochemical, and genetic investigations of adult, definite MIDs. Results: Included were 36 definite MID patients, 19 males, 17 females, aged 29-82y. The diagnosis was based on genetic testing (n=21), on biochemical investigations (n=17), or on both (n=2). The number of organs most frequently affected was four ranging from 1-9. MIMODS was diagnosed in 97% of patients. The organs most frequently affected were the muscle (97%), central nervous system (CNS) (72%), endocrine glands (69%), heart (58%), intestines (55%), and peripheral nerves (50%). The most frequent CNS abnormalities were leucencephalopathy, prolonged visually-evoked potentials and atrophy. The most frequent endocrine abnormalities included thyroid dysfunction, short stature, and diabetes. The most frequent cardiac abnormalities included arrhythmias, systolic dysfunction, and hypertrophic cardiomyopathy. The most frequent MIMODS patterns were encephalomyopathy, encephalo-myo-endocrinopathy, and encepalo-myo-endocrino-cardiopathy. The mean±2SD MIMODS score was 35.97±27.6 (range: 11-71). A MIMODS score >10 was regarded as indicative of a MID. Conclusion: Adult MIDs manifest as MIMODS in the vast majority of the cases. Organs most frequently affected in MIMODS are the muscle, CNS, endocrine glands, and heart. A MIMODS score >10 suggests a MID.

PS1Group1-092 / #238CLINICAL PRACTICE WITH STEROID THERAPY FOR DUCHENNE MUSCULAR DYSTROPHY, A CLINICIAN SURVEY IN ASIAN AND OCEANIA

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Fumi Takeuchi¹, Harumasa Nakamura², Hirofumi Komaki², Ichizo Nishino², Shin’Ichi Takeda², Ikuya Nonaka², Naohiro Yonemoto³

¹The John Walton Muscular Dystrophy Research Centre, Newcastle University, Newcastle upon Tyne, GB;²National Center of Neurology and Psychiatry, Tokyo, JP;³Department Of Biostatistics, Kyoto University School of Public Health, Kyoto, JP

Background: Several studies investigating current clinical practice for Duchenne muscular dystrophy (DMD) have been conducted in Western countries. However, there have been few studies in Asia and Oceania. This study aims to elucidate clinical practice for DMD related to steroid therapy among local experts in Asia and Oceania. Methods: The Asian and Oceanian Myology Center (AOMC) was established in 2001 to facilitate scientific communication and collaboration in neuromuscular disease field in Asian and Oceanian countries. As of 2016, the AOMC executive board members comprised 37 experts from 15 countries in Asia and Oceania (Australia, China, Hong Kong, India, Japan, Malaysia, Myanmar, New Zealand, Pakistan, Philippines, Singapore, South Korea, Taiwan, Iran, and Thailand). We enrolled local experts and/or clinicians who manage DMD patients from the regions by asking AOMC executive board members to nominate potential participants who may meet our inclusion criteria. We included clinicians who: 1) had experience in treating DMD patients; 2) were able to reply to the questionnaire in English. Responses were collected electronically with SurveyMonkey or by mail between December 2015 and June 2016. Responses by mail were inputted into SurveyMonkey on receipt. Data analysis was conducted in Microsoft Excel. The survey consisted of 17 questions regarding the respondent’s personal information (name, gender, age, speciality, and working medical site) and their usual clinical practice for patients with DMD. Results: Among the 15 countries, the executive board members in 13 countries agreed with the study and nominated 148 clinicians. We sent our questionnaire to the 148 clinicians via email in December 2015, and 87 clinicians (Australia: 3, China: 5, Hong Kong: 8, India: 13, Japan: 20, South Korea: 5, Malaysia: 2, Myanmar: 8, Pakistan: 8, Philippines: 2, Singapore: 6, Taiwan: 5, and Thailand: 2) replied by July 2016 (total response rate 62%). Among the 87 clinicians, 79 clinicians (91%) were aware of DMD care recommendations from Bushby et al. (2010). Moreover, 83 clinicians (95%) reported currently managing patients with DMD (i.e., between 2011 and 2015) and 4 clinicians (5%) reported managing patients with DMD only before 2011. The number of DMD patients appeared to differ depending on clinicians, as well as on country. In China, there were more patients with DMD at ages 0-9 and 10-19 years old, while there were more patients ≥20 years old in Japan. Daily prednisolone/prednisone was the most popular treatment regimen at initiation (n=45, 64%), but was less popular at maintenance (n=39, 56%). Steroid therapy for patients after loss of ambulation and medication for bone protection seemed to be controversial. Conclusion: Our results from an international survey of clinicians increase our knowledge of the epidemiology of DMD, as well as current clinical practice for DMD as reported by local experts in Asia and Oceania. It is important to expand registries of patients with DMD in Asia and Oceania and to accumulate real-world longitudinal patient data. These strategies will aid the study of the epidemiology and natural history and could improve treatment and care for patients with DMD worldwide.

PS1Group1-093 / #570EXPERIENCES WITH BARIATRIC SURGERY IN PATIENTS WITH FSHD AND DM1

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Nicol Voermans

Neurology, Radboudumc, Nijmegen, NL

Background: Overweight and obesity are common in patients with facioscapulohumeral dystrophy (FSHD) and myotonic dystrophy type 1 (DM1). Lifestyle change is often challenging for patients with neuromuscular diseases, especially to increase physical activity. Bariatric surgery is a treatment option for adults with severe obesity in whom lifestyle interventions have not been effective. However, very little is known about the benefits and risks in patients with neuromuscular disorders. This study therefore aims to obtain insight into the patients’ perspectives and experiences, the outcome, effects and risks of bariatric surgery in patients with FSHD and DM1. This is expected to improve counseling of patients with FSHD and DM1 who consider bariatric surgery. Methods: A qualitative study, consisting of 14 in-depth interviews with six patients (three FSHD and three DM1), four relatives, three bariatric surgeons and one general practitioner. The study used a qualitative descriptive method. Thematic analysis was used to analyze the data. Results: Four themes were formulated: 1) Overweight as burden; 2) Bariatric surgery as last option; 3) Not your standard patient; and 4) A different life, a different me. Conclusion: This qualitative study shows that bariatric surgery has beneficial physical and mental effects for most patients with FSHD and DM1, and does not influence the muscular disease course. It shows that bariatric surgery is feasible in patients with FSHD and DM1, but specific precautions and a suitable follow-up including tailored dietary and training advices are required. A guideline for the patient and the procedure would be welcome.

PS1Group1-094 / #612AN UNUSUAL PRESENTATION OF GNE MYOPATHY WITH PROMINENT AXIAL MUSCLE WEAKNESS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Jin-Mo Park¹, Jin-Sung Park²

¹Neurology, Dongguk University Gyeongju Hospital, Gyeongju, KR;²Department Of Neurology, Kyungpook National University Chilgok Hospital, Daegu, KR

Background: GNE myopathy is an autosomal recessive myopathy which is previously known as distal myopathy with rimmed vacuoles (OMIM 605820) or hereditary inclusion body myopathy (OMIM 600737). It is caused by biallelic mutation in GNE which is a rate-limiting, bifunctional enzyme in the sialic acid pathway (Eisenberg I 2001). GNE myopathy is clinically characterized by early involvement of tibialis anterior muscle leading to early foot drop, with relatively spared quadriceps muscles. Pathologic study of GNE myopathy frequently shows “rimmed vacuoles” with fiber size variation (Argov Z 1984). However, diagnosis of GNE myopathy can be challenging due to phenotypic variability (Park YE, de Dios JK). We report a GNE myopathy patient with axial muscle involvement, probably triggered by repeated usage of truncal muscles. Methods: A twenty-three year-old man presented with back pain. He was serving in the military service for 6 months and his back pain started after strenuous military activities that require usage of back muscles. He had no past medical history or delay in the milestones. Results: The initial physical examination revealed axial muscle weakness, and mild ankle dorsiflexion weakness. He had hypoactive deep tendon reflexes and no pathologic reflexes. The initial laboratory data were unremarkable except for elevated creatinine kinase level of 1146 IU/L. The electromyography showed evidence of active myopathy with active denervation potentials observed in right tibialis anterior, medial gastrocnemius and thoracic paraspinal muscles. The T1-weighted muscle MRI scans revealed mild fatty infiltrative and asymmetric atrophic changes in bilateral hamstring and soleus muscles. There were marked fatty infiltrations in bilateral lumbar paraspinal muscles. The muscle pathology in the left tibialis anterior muscle showed mild fiber size variation without significant inflammatory infiltrates, but showed rimmed vacuoles that were suggestive of GNE myopathy. The genetic test revealed a pair of compound heterozygous missense mutations in GNE gene, p.V572L and p.A591T, previously reported (NP_–005467.1), that are one of the most common GNE mutations found in Korean and Japanese ethnicities. Conclusion: The decreased sialic acid synthesis due to bialleic mutation in UDP N-Acetylglucosamine 2-epimerase/N-Acetylmannosamine kinase leads to decreased GNE activity is known to cause GNE myopathy. A recent study reported a young male patient who presented with asymmetric hand weakness (De Dios JK, 2014). This report suggested that muscle overuse may be a potential environmental factor that can influence atypical clinical presentation in GNE myopathy. Our patient showed not only unusual onset of symptom but only unique manifestations. The most severe damage site was lumbar paraspinal muscles that is almost complete fatty replaced and atrophied. Meanwhile, anterior compartment of lower legs including tibialis anterior muscle was normal. Several reported axial involvements of GNE myopathy (Argov Z, Chu CC, Park YE). A subset of myopathies that show significant involvement of the axial muscles are known as axial myopathy currently. GNE myopathy is not a disease that is addressed for differential diagnosis (Witting 2016). GNE myopathy has phenotypic variability. In GNE myopathy, environmental factor such as repeated muscle overuse might contribute disease onset and onset site.

PS1Group1-095 / #761HIGHER MRI MUSCLE FAT FRACTION AT SIMILAR AGE IS ASSOCIATED WITH EARLIER LOSS OF AMBULATION IN DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Karin J. Naarding¹, Harmen Reyngoudt², Erik W. Van Zwet³, Melissa T. Hooijmans¹, Brenda L. Wong⁴, Cuixia Tian⁴, Irina Rybalsky⁴, Karen C. Shellenbarger⁴, Julien Le Louër², Pierre G. Carlier², Hermien E. Kan⁵, Erik H. Niks⁶

¹Neurology, Leiden University Medical Center, Leiden, NL;²Aim & Cea Nmr Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, FR;³Department Of Biostatistics, Leiden University Medical Center, Leiden, NL;⁴Neurology, Cincinnati Children’s Hospital Medical Center, Cincinatti, OH, US;⁵C.j. Gorter Center For High Field Mri, Leiden University Medical Center, Leiden, NL;⁶Neurology, Leiden University Medical Center, Leiden, NL

Background: Duchenne muscular dystrophy (DMD) is characterized by progressive replacement of muscle with fat. Full market-approved drugs are lacking. Clinical trials are challenging because of the low prevalence and practical and ethical issues in performing long placebo-controlled studies in children. Muscle fat fraction (FF), measured by quantitative MRI, is considered a potential surrogate endpoint in trials since it is objective and non-invasive. However, such biomarkers are only acceptable as endpoints to regulatory agencies if they are related to clinically meaningful milestones. Therefore, we aimed to assess the additive predictive value of vastus lateralis (VL) FF to age on the loss of ambulation (LoA). Methods: 3-point gradient-echo Dixon images of the right upper leg of DMD patients were acquired at two centers, LUMC and CCHMC, between 2013 and 2016. At the LUMC, images were acquired at baseline, 12 and 24 months on a 3T MR scanner. At CCHMC, scans were acquired on a 1.5T MR scanner at baseline, 6, 12 and 18 months. Weighted mean VL FF was calculated using five slices at the mid-upper leg. FF’s were fitted to a logistic growth-model to predict FF from 0-20 years of age. Slopes of FF curves differed per patient based on FF. Month and year of LoA were determined through a detailed interview with patients and parents, either during regular clinical follow-up, or by telephone between July 2017 and February 2018. This phone call also defined last follow-up for ambulant patients. We fitted a Cox model for the time to LoA with predicted VL FF as the only (time-varying) covariate. Results: At least one VL datapoint was available for 19 LUMC DMD patients (median baseline age 8.9 years, range 5.6-16.1, seven non-ambulant), and for 16 from CCHMC (median baseline age 11.2 years, range 7.6-15.1, all ambulant). Between first MRI and February 2018 LoA occurred in ten DMD patients. VL FF data in relation to age of 35 DMD patients and their superimposed logistic growth-curves are presented in Figure 1. The hazard ratio of a percent increase in VL FF for the time to LoA was estimated at 1.13 (95% confidence interval 1.07-1.18) which was highly significant (Wald test, p<0.001). Conclusion: Vastus lateralis fat fraction has a significant additive predictive value to age on the date of loss of ambulation. This direct relation supports the use of quantitative MRI as an outcome measure for future clinical trials in DMD.

PS1Group1-096 / #1018TOR1A VARIANTS CAUSE A SEVERE ARTHROGRYPOSIS WITH DEVELOPMENTAL DELAY, STRABISMUS AND TREMOR

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Ariana Kariminejad¹, Martin Dahl-Halvarsson², Gianina Ravenscroft³, Fariba Afroozan¹, Elham Keshavarz⁴, Hayley Goullée³

¹Kariminejad-Najmabadi Pathology & Genetics Center, Tehran, IR;²Department Of Pathology, University of Gothenburg, Sahlgrenska University Hospital, Gothenburg, SE;³Centre For Medical Research, The University of Western Australia and the Harry Perkins Institute for Medical Research, Nedlands, AU;⁴Department Of Radiology, Mahdieh Hospital, Shahid Beheshti University of Medical Science, Tehran, IR

Background: Autosomal dominant torsin dystonia 1 is a disease with incomplete penetrance most often caused by an in-frame GAG deletion (p.Glu303del) in the endoplasmic reticulum luminal protein torsinA encoded by TOR1A. Methods: 25 cases of AMC with congenital contractures in more than two joints and in multiple body areas were collected through international collaboration and medical history, physical examination and imaging were performed. Next-generation sequencing was performed on DNA from patients. Results: We report an association of the homozygous dominant disease-causing TOR1A p.Glu303del mutation, and a novel homozygous missense variant (p.Gly318Ser) with a severe arthrogryposis phenotype with developmental delay, strabismus and tremor in three unrelated families. All parents who were carriers of the TOR1A variant showed no evidence of neurological symptoms or signs, indicating decreased penetrance similar to families with autosomal dominant torsin dystonia 1. The results from cell assays demonstrate that the p.Gly318Ser substitution causes a redistribution of torsinA from the endoplasmic reticulum to the nuclear envelope, similar to the hallmark of the p.Glu303del mutation. Conclusion: Our study highlights that TOR1A mutations should be considered in patients with severe arthrogryposis and further expands the phenotypic spectrum associated with TOR1A.

PS1Group1-097 / #877NDUFAF3 VARIANTS THAT DISRUPT MITOCHONDRIAL COMPLEX I ASSEMBLY CAUSE ASSOCIATE WITH CAVITATING LEUKOENCEPHALOPATHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Akihiko Ishiyama¹, Kazuhiro Muramatsu², Shunpei Uchino³, Chika Sakai³, Yuichi Matsushima³, Nishiki Makioka², Tomomi Ogata², Eriko Suzuki², Hirofumi Komaki¹, Masayuki Sasaki¹, Masakazu Mimaki⁴, Yu-Ichi Goto³, Ichizo Nishino⁵

¹Department Of Child Neurology, National Center Hospital, National Center Of Neurology And Psychiatry, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, JP;²Department Of Pediatrics, Gunma University Graduate School Of Medicine, Gunma University Graduate School of Medicine, Maebashi, JP;³Department Of Mental Retardation And Birth Defect Research, National Institute Of Neuroscience, National Center Of Neurology And Psychiatry, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, JP;⁴Department Of Pediatrics, Faculty Of Medicine, Teikyo University, Faculty of Medicine, Teikyo University, itabashi, JP;⁵Department Of Neuromuscular Research, National Institute Of Neuroscience, National Center Of Neurology And Psychiatry, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, JP

Background: Genetic abnormalities in mitochondrial complex assembling factors are associated with leukoencephalopathy. However, genotype-phenotype correlations remain elusive. Methods: We present a one-year-old girl with consciousness disturbance after a respiratory infection. Brain MRI revealed leukoencephalopathy with bilaterally symmetrical hyperintensity in the substantia nigra, medial thalamic nuclei, and basal nuclei, as well as cavities in the cerebral white matter and corpus callosum. Lactate levels in the spinal fluid were high, while magnetic resonance spectroscopy of the cerebral white matter and basal nuclei showed high peak lactate levels, suggesting mitochondrial dysfunction. After 2 months of hospitalization, her developmental status returned to that before admission. She acquired the ability to speak meaningful words at 2 years and 6 months and walked independently at 3 years. However, there was no deterioration in language comprehension, but her motor function deteriorated: her sitting posture became slightly unstable, and she could not walk without assistance at 4 years. Results: A muscle biopsy was performed on the biceps brachii at 3 years, revealing no pathological findings characteristic of mitochondrial-related diseases. Mitochondrial respiratory chain complex activities were analyzed in the skeletal muscle. Complex I activity levels, normalized to the activities of complex II and citrate synthase, were 17% and 21%, respectively, but complex III and V activity levels were mildly decreased. Whole exome sequencing identified compound heterozygous variations in NDUFAF3, involved in the assembly of mitochondrial complex I (c.342_–343insGTG:p.117 Valdup, c.505C>A:p.Pro169Thr). Two-dimensional blue native polyacrylamide gel electrophoresis (PAGE) and sodium dodecyl sulfate-PAGE revealed reductions in Q-module (NDUFS2, NDUFS3, and NDUFA9) and P-module (NDUFB10 and NDUFB11) subunits, indicating disruption of mitochondrial complex I assembly. Conclusion: Few studies on the assembly of mitochondrial respiratory chain complexes have been conducted, and the phenotypes and pathologies of associated diseases are not completely understood. Our result suggests leukoencephalopathy with cavities associates with NDUFAF3 mutations and expands the clinical phenotypes associated to impaired assembly factor for mitochondrial complex I.

PS1Group1-098 / #979RESTRICTION ENZYME CLEAVAGE OF PCR PRODUCTS ALLOWS GENOTYPING MDX3CV, MDX4CV AND MDX5CV ALLELES WITHOUT SEQUENCING

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Laurence A. Neff, Elinam Gayi, Leonardo Scapozza, Olivier M. Dorchies

School Of Pharmaceutical Sciences, University of Geneva, Geneva, CH

Background: Duchenne muscular dystrophy (DMD) is due to the absence of dystrophin. It is characterized by progressive muscle wasting and premature death. The exploration of the pathogenic mechanisms and the evaluation of therapeutic options rely mostly on dystrophic mice. The mdx mouse originates from a spontaneous mutation that arose in a colony of C57BL/10 mice in the 1980’s. Since then, it has become the most commonly used animal model of DMD. In the 1990’s, several allelic variants of the mdx mouse, namely the mdx^2Cv, mdx^3Cv, mdx^4Cv, and mdx^5Cv, have been recovered from chemical mutagenesis in the C57BL/6J background. The different strains are characterized by differential expression of naturally occurring shorter isoforms (C-terminus truncated) of dystrophin in a tissue-dependent manner: The mdx^2Cv, mdx^3Cv and mdx^4Cv strains are useful for studying the roles of dystrophin and dystrophin-associated glycoprotein complex in non-muscle tissues such as the retina, kidney, and brain. The mutations carried by the mdx^4Cv and mdx^5Cv mice are characterized by the absence of revertant fibres, an advantage for evaluating gene-, virus, or cell-mediated dystrophin restoration. Until now genotyping of this strains requires sequencing of PCR product. Here we propose a simple restriction base method allowing genotyping without sequencing. Methods: Sequence analysis revealed that the mdx^3Cv and mdx^5Cv alleles bear restriction sites for AluI, and HphI, respectively, which are absent from the wild type alleles. The mdx^4Cv mutation disrupts a restriction site for Alw26I (BsmAI), which is normally present on the wild type allele. Based on these findings, we designed new strategies for genotyping these dystrophic strains using PCR amplification followed by enzymatic restriction of the PCR products. Results: Here we show that PCR followed by restriction digestion provides an easy mean to discriminate wt, heterozygous and homozygous mice bearing mdx^3-5Cv alleles. We demonstrated the excellent stability to freeze-thaw cycles of the PCR and restriction enzyme master mixes and we optimized a number a protocol steps. The resulting protocols are user-friendly and allow straightforward genotyping at minimum cost and hands-on time. Conclusion: The mdx^3Cv, mdx^4Cv, and mdx^5Cv strains all carry point mutations. Conventional genotyping involves PCR amplification, yielding amplicons of same sizes, followed by allele identification by sequencing, a step that is often outsourced, causing extra cost and delay in analysis. By contrast, our procedure is time and cost effective: genotyping is achieved within a day using standard molecular biology techniques and eliminates extra cost for sequencing.

PS1Group1-099 / #462CLINICO-PATHOLOGICAL CORRELATIONS IN IDIOPATHIC INFLAMMATORY MYOPATHIES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Endre Pál¹, Katinka Gulyas², Tünde Minier², Timea Berki³, Laszlo Czirjak², Cecilia Varju²

¹Neurology, University of Pécs, Pécs, HU;²Rheumatology And Immunology, University of Pécs, Pécs, HU;³Immunology And Biotechnology, University of Pécs, Pécs, HU

Background: Idiopathic inflammatory myopathies (IIM) are heterogeneous systemic autoimmune diseases, characterised by muscle weakness, various organ involvements and the presence of specific autoantibodies. Our aims were to classify patients according to the clinical features, muscle histology findings and autoantibody profiles. Methods: 82 patients with muscle biopsy proven IIM were included in the study. Muscle biopsy, myositis specific (MSA) and myositis associated (MAA) antibody tests were performed in each patient before starting the immunomodulatory treatment. The MSAs and MAAs (Jo-1, PL-7, PL-12, Mi-2, SRP, Pm-Scl, Ku, ribosomal, AMA-M2) were tested with Western-blot kit. The ANA, dsDNA, ENA, Sm, Sm/RNP, SS-A and SS-B antibody examinations were performed with ELISA tests. Dermatomyositis/DM/, polymyositis /PM/, juvenile PM/DM, inclusion body myositis /IBM/, overlap myositis /OM/ and immune mediated necrotizing myopathy /IMNM/ were identified based on clinical data, immunserology and muscle biopsy. Survival analysis was perfomed by Kaplan Meier test. Results: 59 women and 23 men with a mean age of 49.3 ± 14.6 years were included. Mean follow-up of the patients was 7.5 ± 4.5 years. The distribution of myositis subsets was: 30.5% (n=25) DM, 26.8% (n =22) PM, 22% (n=18) OM, 11% (n=9) IMNM, 8.5% (n=7) IBM, and 1.2% (n=1) juvenile PM/DM. Lung fibrosis (51.2%), arthritis (51.2%), Raynaud’s phenomenon (42.7%), skin symptoms (45.1%), dysphagia (24.4%) and significant cardiac involvement (15.9%) were the most prevalent disease-manifestations. Fifteen cases were associated with malignancies, mjority of them was classified as IMNM (7 out of 9 patients). 18 patients died of myositis related events: 8 patients died of malignancies (4 in the IMNM, 2 in the PM and 2 in the DM group), 6 died related to cardiac conditions, 2 in lung fibrosis and 2 caused by infections. The worst prognosis with a 10 year survival of approximately 31.1% of patients was seen in the IMNM subgroup, followed by patients with PM (68.4%) and DM (85.3%). Patients with antisynthetase antibody-positivity had worse prognosis compared with patients with other antibodies or no identifiable antibodies. The worst prognosis was seen in patients with both MSA and MAA positivity and the best in patients with no identifiable MSA and MAA. Conclusion: Complex clinicopathologic assessment is recommended for classification and management of idiopathic inflammatory myopathy cases. Muscle histology is still an important diagnostic tool in IIMs. IMNM and PM are associated with worse prognosis compared to other types of IIMs.

PS1Group1-100 / #537FIRST REPORTED VARIANT AT THE TRIM32 RING DOMAIN IN A PEDIGREE WITH LIMB-GIRDLE MUSCULAR DYSTROPHY AND BARDET-BIEDL SYNDROME

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Ana L. Pelayo-Negro¹, Miguel A. Fernández-García², Patricia Blanco-Arias², Elena Gallardo-Agromayor³, Gerardo Gutierrez-Gutierrez⁴, José Berciano¹

¹Neurology, University Hospital Marqués de Valdecilla, Santander, ES;²Neurology, Health in Code, A Coruña, ES;³Radiology, University Hospital Marqués de Valdecilla, Santander, ES;⁴Neurology, University Hospital Infanta Sofía, Madrid, ES

Background: Pathogenic variants in TRIM32 have been related to limb-girdle muscular dystrophy type 2H (LGMD2H, OMIM#254110). To date, most reported variants lead to a truncated protein and are clustered at the C-terminal NHL-repeat domain. Whole gene deletions have also been described. Additionally, a missense change in the B-box motif was found in a family with Bardet-Biedl syndrome (BBS11, OMIM#615988). Methods: A 60-year-old woman began in the 4th decade with LL weakness, inability to run or stand from sitting or lying position and slow progression with difficulties in walking, fatigue and frequent falls. She had mild atrophy of pelvic and thigh muscles, CK 250UI/L, myopathic EMG pattern; not willing to perform muscle biopsy to date. She was born of healthy consanguineous parents and had two affected siblings with a similar phenotype and hypogonadism. Additionally, she had a healthy brother and a daughter, aged 37, that recently complained of fatigue and clumsiness with normal EMG and CK levels. Next-generation sequencing of 34 LGMD-related genes identified a homozygous 1bp-insertion in TRIM32, predictably originating a frameshift (NM_–012210.3:c.115_–116insT; NP_–036342.2:p.Cys39Leufs*17). Both affected siblings were also confirmed as homozygous; father, healthy brother and daughter were heterozygous carriers. Results: This is the first reported pathogenic variant at the TRIM32 N-terminal RING domain. Homozygous whole gene deletions confirmed that a total loss of protein function resulted in LGMD2H without greater clinical severity. Despite TRIM32 recessive behaviour, some descriptions of heterozygous carriers found mild clinical symptoms and vacuolar changes in muscle biopsies, suggesting a mild dominance pattern. In our family, father and brother of the index case (aged 92 and 50, respectively) had no neuromuscular abnormalities; in contrast, the daughter (37yo) complained about mild symptoms, suggesting the possibility of some light dominancy of the TRIM32 variant. On the other hand, TRIM32 has been linked to BBS11: a syndromic form of obesity with pigmentary retinopathy, renal anomalies, cognitive problems and hypogonadism. To date, only a Bedouin family carrying the p.Pro130Ser missense variant, located at the N-terminal B-box motif, has been described. However, none of the patients with complete TRIM32 deletion showed systemic features. In our family, two siblings have hypogonadism, suggesting the possibility of an association with BBS11. Conclusion: This would be the first report of BBS features in a LGMD2H affected family and should highlight the importance of a thorough phenotypic evaluation of TRIM32 patients to further delineate this association, particularly if other RING-domain pathogenic variants shall be identified.

PS1Group1-101 / #572MUSCLE SPECIFIC KINASE PROTECTS MDX MOUSE MUSCLES AGAINST ECCENTRIC CONTRACTION-INDUCED LOSS OF STRENGTH

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

William D. Phillips, Joanne Ban, Sofie Trajanovska

Physiology & Bosch Institute, The University Of Sydney, Sydney, NSW, AU

Background: Muscles of mdx mice lack dystrophin, providing a mouse model for Duchenne muscular dystrophy (DMD). Eccentric contractions applied to mdx muscles cause an acute drop in force, reflecting the vulnerability of dystrophin-deficient muscles to injury. It has been reported that mdx muscles express less Muscle Specific Kinase (MuSK) and that this might predispose their neuromuscular junctions to eccentric contraction-induced damage. Methods: To increase the level of expression of MuSK we injected the tibialis anterior muscles of 8-week old male mdx and C57BL10 (wild-type background) mice with recombinant adeno-associated viral vector (AAV) encoding MuSK fused to green fluorescent protein (MuSK-GFP). Contralateral control muscles were injected with empty AAV vector. One month later the mice were anaesthetized with 2-3% inhaled isoflurane/oxygen and maximum tetanic force was recorded in response to direct muscle stimulation or stimulation via the nerve. Eccentric contractions (forced lengthening to 1.25 time optimal length) were imposed during maximum (directly evoked) activation of the muscle in situ. Maximum isometric force was recorded before, and one hour after, a series of four such eccentric contractions. Results: Consistent with previous studies mdx muscles were more vulnerable to injury compared to C57BL10 wild-type mice. After the series of four eccentric (stretch) contractions, mdx muscles retained only 73 ± 2% (mean ± SEM) of their original (pre-stretch) maximum isometric force. In contrast, mdx muscles expressing MuSK-GFP retained significantly more of their original force after identical ECs (84 ± 1%; p<0.01). Rapsyn, an established downstream effector of MuSK signaling, conferred similar protection to mdx muscles. The protective effect was evident even when isometric force was elicited by direct muscle stimulation. Conclusion: These results indicate that enhanced MuSK signaling can protect dystrophin-deficient muscle fibers from acute eccentric contraction-induced loss of force. Moreover they suggest that the MuSK/rapsyn signaling pathway can act downstream of neuromuscular transmission to protect the sarcolemma of from tension-induced injury.

PS1Group1-102 / #645NOVEL LMNA GENE MUTATION PRESENTING WITH DILATED CARDIOMYOPATHY AND LIMB-GIRDLE MUSCULAR DYSTROPHY TYPE 1B

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Martha Spilioti¹, Konstantinos Notas¹, George Stavropoulos², Georgios Efthimiadis³, Kleita Michaelidou⁴, Ioannis Zaganas⁴, Maria Moschou¹, Marianthi Arnaoutoglou¹, Magdalini Tsolaki¹

¹1st Department Of Neurology, Ahepa General Hospital, Aristotle University of Thessaloniki, Thessaloniki, GR;²2nd Cardiology Department, Hippokration General Hospital, Aristotle University of Thessaloniki, Thessaloniki, GR;³1st Cardiology Department, Ahepa University Hospital, Aristotle University of Thessaloniki, Thessaloniki, GR;⁴Department Of Neurology, School Of Medicine, University of Crete, Heraklion, Crete, GR

Background: Lamins A and C, encoded by the lamin A/C gene (LMNA), are major components of the nuclear lamina, a fibrillar network that sustains the structural integrity and stability of the nuclear envelope. Additionally, lamins are involved in multiple cellular processes, such as chromatin organization, DNA replication and gene regulation. LMNA gene mutations have been shown to cause several inherited diseases known as laminopathies, which include cardiac and skeletal myopathies, lipodystrophy, metabolic disorders, peripheral neuropathy and premature aging syndromes. Heart involvement counts as the most common feature, regardless of the presence of a myopathy and is characterized by conduction system disorders, arrhythmias, dilated cardiomyopathy and arrhythmogenic right ventricular cardiomyopathy. Many LMNA mutation carriers are at risk of sudden cardiac death, due to ventricular arrhythmias, high-degree atrioventricular block and end-stage heart failure. LMNA-related myopathies represent a subgroup with different phenotypes, based on the distribution of muscle weakness or age at onset: limb-girdle muscular dystrophy type 1B (LGMD1B), autosomal dominant Emery-Dreifuss muscular dystrophy and congenital muscular dystrophy. LGMD1B typically causes progressive muscle weakness in the proximal muscles of the lower limbs. Methods: We herein present a 47 years old female patient, with a medical history of arrhythmias, second degree atrioventricular block, dilated cardiomyopathy (confirmed via magnetic resonance imaging) and weakness of the proximal muscles, with distinct myopathic features in the electromyography. Cardiac and skeletal muscle involvement developed gradually during her third decade of life. Family history was positive for sudden cardiac deaths and dilated cardiomyopathy (Figure 1), indicating a possible autosomal dominant manner. Genomic DNA was extracted from patient’s peripheral blood and Whole Exome Sequencing (WES) was performed on Illumina HiSeq 2000/2500 platform. A comprehensive bioinformatics analysis for data interpretation was done using Ingenuity software (Qiagen).

Results: We identified a novel splice site variant (c.1272+2T>C) in LMNA gene in the heterozygous state in our patient. This genetic variant results in splice site loss and in silico analysis using different bioinformatic tools predicted that it exerts a pathogenic effect. In order to verify segregation of this genetic variant in LMNA gene with disease, several affected and unaffected members of the family were tested with pending results. Conclusion: Laminopathies can present with a vast clinical spectrum and should be suspected in patients with conduction system disorders, dilated cardiomyopathy and muscle weakness. We report a novel LMNA gene mutation in a female patient, presenting with dilated cardiomyopathy and myopathy, underlining the genetic diagnostic value and cost effectiveness of WES.

PS1Group1-103 / #498LONGTERM APPLICATION OF HUMAN IMMUNOGLOBULIN G FOR EXPERIMENTAL TREATMENT OF DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Jana Zschüntzsch¹, Pia V. Jouvenal¹, Yaxin Zhang², Florian Klinker³, Malte Tiburcy⁴, David Liebetanz³, Heinrich Brinkmeier², Dörthe Malzahn⁵, Jens Schmidt¹

¹Neurology, University medical Center Göttingen, Göttingen, DE;²Institute Of Pathophysiology, University Medicine Greifswald, Karlsburg, DE;³Clinical Neurophysiology, University medical Center Göttingen, Göttingen, DE;⁴Institute Of Pharmacology And Toxicology, University medical Center Göttingen, Göttingen, DE;⁵mzBiostatistics, Göttingen, DE

Background: Duchenne muscular dystrophy (DMD) is a progressive, muscle wasting, inherited X-linked muscle disease caused by mutations in the dystrophin gene. The pathology consists of structural instability of the dystrophin-glycoprotein-complex (DGC), muscle degeneration, and various degrees of myoinflammation depending on the disease stage. Current treatments have targeted the genetic defect or the inflammatory response. So far, the standard treatment by glucocorticosteroids is limited because of numerous side effects. A previous study addressed the early disease phase of the well-established mdx mouse model for DMD and demonstrated an improvement of clinical and paraclinical parameters upon treatment with human immunoglobulins (IgG). The aim of the present study was to confirm the effectiveness of human IgG in a long-term preclinical study in mdx mice. Methods: Human IgG (Privigen, CSL Behring) at a dosage of 2g/kg BW or saline (NaCl) as control was administered monthly by intraperitoneal injections in mdx mice over 18 months beginning at 4 weeks of age. Advanced voluntary wheel running parameters were recorded continuously over the entire study period. Cardiac ultrasound was performed every three months and grip strength measurements every week. After 18 months, animals were sacrificed. Blood and muscle were sampled for ex vivo muscle contraction tests, quantitative PCR and histological analysis. Results: IgG compared to NaCl significantly improved the voluntary running performance and grip strength. The muscle fatigability and specific tetanic force in an ex vivo muscle contraction test remained unchanged upon IgG. A significant benefit of cardiac function was evidenced by improved fractional area shortening and ejection fraction upon human IgG. These results were supported by a reduced cardiac fibrosis and infiltration of T- cells as well as macrophages. Despite an unchanged mRNA expression of the relevant inflammatory markers TGF-beta, SPP1 and MCP1, a significant reduction of T- cells and macrophages in representative muscles (diaphragm, M. tibialis anterior, M. gastrocnemicus and M. quadriceps) was observed by immunohistochemistry in mdx mice treated with human IgG compared to controls. These findings were underlined by reduced myopathic changes upon human IgG in the same muscles. Conclusion: Taken together, this study demonstrates a beneficial effect of 18 months of IgG treatment in mdx mice, evidenced by improved voluntary wheel running parameters, cardiac function and reduced histopathological changes of the skeletal muscle, diaphragm and heart. Our long- term study underlines the importance of myoinflammatory contribution to the disease progression of DMD/ mdx and shows the therapeutic effectiveness of human IgG in the mdx mouse. Human IgG is usually well tolerated and might be a useful treatment option beside mutation-based therapies for DMD patients. The data call for a clinical trial with IgG in DMD.

PS1Group1-104 / #675BODY COMPOSITION ANALYSIS IN PATIENTS WITH MYOTONIC DYSTROPHY TYPE 1 AND 2

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Stojan Peric¹, Milorad Vujnic², Tanja Nisic³, Marija Banovic⁴, Bogdan Bjelica⁵, Ivo Bozovic⁵, Jovan Pesovic⁶, Dusanka Savic-Pavicevic⁶, Ivana Basta⁵, Zorica Stevic⁵, Dragana Lavrnic⁵, Vidosava Rakocevic-Stojanovic⁵

¹Neurology Clinic, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia, Belgrade, RS;²Faculty of Medicine, Banja Luka, BA;³Center for Obesity, Clinic of Endocrinology, Diabetes and Metabolic Disease, Belgrade, RS;⁴School of Medicine, Belgrade, RS;⁵Neurology Clinic, Clinical Center of Serbia, School of Medicine, University of Belgrade, Belgrade, Serbia, Belgrade, RS;⁶Faculty of biology, Belgrade, RS

Background: Myotonic dystrophies (DM1) are inherited, slowly progressive, multisystem diseases. There are only several reports about body composition in DM1 and no data for DM2. The aim of this research was to analyze the body composition of patients with DM1 and DM2, and also to examine the association between body composition and socio-demographic/clinical features of patients. Methods: Body composition was assessed by DEXA (Dual-Energy X-ray Absorptiometry) in 22 DM1 and 12 DM2 patients. A tree compartment model was used: bone mineral content (BMC), fat mass (FM) and lean tissue mass (LTM). Results: Patients with DM1 and DM2 had similar total body mass, BMC, FM and LTM. Patients with DM1 had higher trunk limb fat index (TLFI) that indicated higher accumulation of fat mass in abdominal area (visceral obesity) (1.16 ± 0.32 for DM1 vs. 0.87 ± 0.23 for DM2, p<0.05). Right ribs bone mineral density was worse in DM2 group (0.68 ± 0.07 g/cm² vs. 0.61 ± 0.09 g/cm², p<0.05). The percentage of FM in legs of DM1 subjects showed negative correlation with the strength of proximal leg muscles (ρ=-0.47, p<0.05). The strength of muscles in DM2 was in correlation with bone density (ρ=+0.62, p<0.05 for upper arm muscles, ρ=+0.87, p<0.01 for lower arm muscles, ρ=+0.72, p<0.05 for lower leg muscles). Conclusion: Patients with DM1 had visceral obesity and percentage of fat mass correlated with a degree of muscle weakness. In patients with DM2 lower bone mineral content was noticed. Higher degree of muscle weakness was in correlation with lower bone density in DM2.

PS1Group1-105 / #795EVALUATING THE EFFECTS OF BASELINE VARIABLES ON THE RESPIRATORY FUNCTION BENEFIT OF IDEBENONE IN DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Shabir Hasham¹, Thomas Meier¹, Mika Leinonen¹, Thomas Voit², Oscar H. Mayer³, Gunnar Buyse For The Delos Study Group⁴

¹Santhera Pharmaceuticals, Pratteln, CH;²UCL Great Ormond Street Institute of Child Health, London, GB;³Children’s Hospital of Philadelphia , Philadelphia, PA, US;⁴University Hospitals Leuven, Leuven, BE

Background: Respiratory function decline is a major cause of morbidity and mortality in patients with Duchenne muscular dystrophy (DMD). The randomized, placebo-controlled Phase 3 DELOS trial assessed the safety and efficacy of idebenone in DMD patients already in respiratory decline and not taking concomitant glucocorticoids (GCs). This trial demonstrated that idebenone significantly slowed respiratory function loss, measured as peak expiratory flow (expressed as a percentage of predicted, PEF%p) – the primary endpoint. The objective of this analysis is to evaluate the effect of idebenone in various patient subgroups of the DELOS trial. Methods: Respiratory function data were prospectively collected from 64 DMD patients aged 10-18 years and already in respiratory decline (PEF%p < 80%). The consistency of the effect of idebenone in DELOS was investigated by analyzing change in PEF%p from baseline to week 52 (study end) in subgroups defined by prior GC use (naïve vs previous user), age (<14 years vs ≥14 years), baseline PEF%p (<50% vs ≥50%), weight (<58 kg vs ≥58 kg) and ambulatory status. Each subgroup was analyzed using a mixed model for repeated measures, a similar approach to that used in the primary analysis. Results: The observed treatment difference in PEF%p at week 52 between idebenone and placebo was 6.3% in the total intention to treat population (p=0.03). Similar PEF%p treatment differences in favor of idebenone were observed regardless prior GC use, age, baseline PEF%p, weight or ambulatory status – varying from 4.2% to 7.3%. Of note, the treatment difference in prior GC users was 6.73% compared to 6.19% in GC-naïve patients. No significant interactions between the treatment group and subgroup factors were observed. Conclusion: The previously reported treatment effect of idebenone on PEF%p was consistent in a broad population of DMD patients, regardless of previous GC use, age, weight, ambulatory status or severity of respiratory decline at treatment initiation. These results suggest that none of these factors significantly influence the respiratory function benefits of idebenone in patients with DMD.

PS1Group1-106 / #984NOVEL RYR-CALSTABIN STABILIZERS WITH THERAPEUTICAL POTENTIAL FOR DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Garazi Aldanondo¹, Haizpea Lasa-Fernandez¹, Jaione Lasa-Elgarresta¹, Jose Ignacio Miranda², Jesus Maria Aizpurua², Adolfo López De Munain¹, Ainara Vallejo-Illarramendi¹

¹Biodonostia Institute, Donostia-San Sebastian, ES;²UPV/EHU, Donostia-San Sebastian, ES

Background: Several studies indicate that calcium is dysregulated in the muscles from patients with Duchenne and Becker muscular dystrophy. In the mdx mouse model of Duchenne muscular dystrophy (DMD), the sarcoplasmic reticulum ryanodine receptor RyR1 and RyR2 are abnormally nitrosylated and this leads to calstabin depletion from the protein complex and subsequent calcium leak through these channels. RyR modulators enhance RyR-Calstabin binding preventing calcium leak, reducing muscle damage and improving muscle function. Methods: We have generated a family of small molecules, namely Ahulken compounds (AHK), which bind RyRs and modulate their activity. In this work we have analyzed the in vivo and in vitro effect of the novel RyR stabilizers AHK1 and AHK2, in the mdx mouse model and in human immortalized myotubes. Results: Treatment of human myotubes with AHK compounds for 12 hours enhanced RyR-calstabin binding, and normalized resting cytosolic calcium levels. Moreover, no toxicity was observed in myotubes treated with high concentration (2 mM) of AHK compounds. Treatment of mdx mice with AHK modulators during 5 weeks normalized intracellular calcium levels in muscle fibers, reduced biochemical and histological evidence of muscle damage and improved muscle function. Moreover, AHK2 also improved specific CNS and cardiac muscle deficiencies observed in mdx mice. Conclusion: Our study shows that AHK modulators ameliorate dystrophic phenotype in cellular and animal models of Duchenne muscular dystrophy. In addition, our results consolidate RyR-calstabin complex as a useful therapeutic target for drug development against muscular dystrophies as well as other disorders with subjacent nitro-oxidative stress.

PS1Group1-107 / #501THE EFFECT  OF UNCARIA TOMENTOSA IN DIAPHRAGM MUSCLE OF MDX DYSTROPHIC MICE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

David Feder¹, Alzira A.S. Carvalho², Bruno M. Bertassoli¹, Lucas P. Giordani¹, Giuliana Petri¹, Fabio F. Perazzo³, Beatriz C.A. Alves⁴, Matheus M. Perez⁴, Fernando L.A. Fonseca⁴

¹Pharmacology, Faculdade de Medicina do ABC, Santo Andre, BR;²Neurology, Faculdade de Medicina do ABC, Santo Andre, BR;³Pharmaceutical Sciences, Universidade Federal de São Paulo, Santo Andre, BR;⁴Laboratory Analysis, Faculdade de Medicina do ABC, Santo Andre, BR

Background: Duchenne Muscular Dystrophy (DMD) is a severe muscle wasting disease caused by mutations in dystrophin gene. This deficiency leads to sarcolemma instability, inflammation, muscle degeneration and fibrosis. Uncaria tomentosa (UT) is a medicinal plant with anti-viral, anti-mutagenic, anti-inflammatory and antioxidant properties. The objective of study was evaluating the effect of UT in diaphragm muscle of mdx dystrophic mices. Methods: 8-weeks-old male mdx mice were treated, 10 mice with 200 mg/kg of UT extract orally during 30 days (UT group) and 6 mice received saline solution orally during 30 days (control group). Creatine kinase (CK) was measured on the day of euthanasia. H&E stained frozen section of the muscle biopsy of diaphragm (DIA) was performed in order to analyze number of internal nuclei and minimal Feret diameter. In addition, gene expression of transforming growth factor-ß1 (TGF-ß1), tumor necrosis factor-a (TNF-a), osteopontin (OSP) and Myostatin (Myo) were determined by quantitative real time polymerase chain reaction (qRT-PCR). Data are presented as mean ± standard error of mean. One-way or two-way ANOVA and Bonferroni test were used for analysis of variance to determine the statistical significance, followed by the least significant difference (LSD) analysis, using Prism Statical software (Graphpad, San Diego, CA). P < 0.05 was considered statistically significant. Results: CK levels were significantly higher in UT group. UT treatment did not prevent muscle damage, indicated by increase of central nucleated fibers with a concomitant increase in number of small fibers (0-30 μM). By other side, It had an effect on the inflammatory process demonstrated by decrease in TNF-a, TGF and osteopontin expression (figure 1)

Conclusion: So, in this study, we evaluated the anti-inflammatory properties of Uncaria tomentosa against myonecrosis and inflammatory response in the diaphragm muscle of mdx mice. Uncaria tomentosa downregulates the TNF-a, TGF and osteopontin expression indicating improving of inflammatory role however, there was a worsening of the dystrophic phenotype in the diaphragm muscle, indicated by increase of CK level, number of central nucleated fibers and small fibers diameter. Perhaps, as many inflammatory pathways are triggered in muscular dystrophy, it is possible that Uncaria tomentosa, alone, is insufficient to halt the whole process.

PS1Group1-108 / #620MYTOBLOTS FOR THE EVALUATION OF NEW TREATMENTS IN NEUROMUSCULAR DISORDERS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Estibaliz Ruiz-Del-Yerro¹, Patricia Soblechero-Martin², Irene Larrañaga¹, Edurne Albiasu-Arteta¹, Virginia Arechavala-Gomeza³

¹Neuromuscular Disorders, Biocruces Health Research Institute, Barakaldo, ES;²Neuromuscular Disorders Group, Biocruces Helath Research Institute, Barakaldo, ES;³Neuromuscular Disorders, Biocruces Health Research Institute, Barakaldo, ES

Background: New therapies for neuromuscular disorders often require to be studied in patient’s cell cultures. Many potential therapies for Duchenne Muscular Dystrophy (DMD) aim to alter the expression of key proteins, such as dystrophin or utrophin, but, as muscle cell cultures from DMD patients are scarce and do not grow or differentiate well, only a limited number of candidate drugs are tested. Moreover, dystrophin and utrophin quantification by western blotting requires a large number of cultured cells; so fewer compounds are evaluated as thoroughly as it is desirable. Methods: We have developed a quantitative assessment tool using fewer cells to contribute in the screening of better drug candidates: an “in-cell-western”, also known as cytoblot, is a quantitative immunofluorescence assay performed in microplates that makes possible the quantification of proteins directly in cell culture, combining the specificity of western blotting with the reproducibility and throughput of ELISA. Results: Our group has recently optimized the assay (‘myoblot’) to quantify several muscle proteins in differentiated myoblast cultures and we are using this method to assess dystrophin restoration treatments, drugs that aim to increase the expression of utrophin and others that alter the differentiation of cultures. Conclusion: We expect that the use of myoblots will accelerate the development and validation of new therapies.

PS1Group1-109 / #622PHENOTYPE-GENOTYPE RELATIONS IN FACIOSCAPULOHUMERAL MUSCULAR DYSTROPHY TYPE 1

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Karlien Mul¹, Richard J. Lemmers², Corinne G. Horlings³, Patrick J. Van Der Vliet², Marianne A. Jonker⁴, Nicol C. Voermans³, Silvere M. Van Der Maarel², Baziel G. Van Engelen³

¹Neurology, Radboud University Medical Center, Nijmegen, NL;²Human Genetics, leiden University medical Center, Leiden, NL;³Neurology, Radboud University Medical Center, Nijmegen, NL;⁴Health Sciences, Radboud University Medical Center, Nijmegen, NL

Background: Facioscapulohumeral muscular dystrophy (FSHD) is characterized by large variability in disease severity and penetrance, that is only partially explained by the current knowledge on the disease mechanism. This study integrates previous findings on phenotype-(epi)genotype relations to assess how much of the clinical variability can be explained. Additionally, clinical scores per body region are used to refine the interpretation of (epi)genetic data. Methods: We included 148 FSHD1 patients from 49 different families and performed genetic testing (D4Z4 repeat array size, haplotype, and D4Z4 methylation), extensive clinical evaluation (clinical severity scores, manual muscle testing, motor function measure, facial weakness score), and muscle MRI of the leg muscles. Results: The explained variability in disease severity by familial factors, including the D4Z4 repeat array size, was approximately 40%. Asymptomatic gene carriers had longer repeat sizes compared to symptomatic individuals (7.3 vs 6.2 units, p=0.001). The D4Z4 methylation (Delta1 value) was not useful as a prognostic factor for disease severity and penetrance on an individual level. The D4Z4 repeat array size explained approximately 29% and 15% of the variability in the involvement of the facial muscles and upper extremity muscles respectively. Involvement of the leg muscles was influenced by age, but only to a very limited extent by the repeat array size (explained variance approximately 3%). Conclusion: This study provides additional evidence that other disease modifying factors play an important role in the clinical variability of FSHD patients, since only 40% of the variability can be attributed to familial factors. Possibly, the facial muscles are more sensitive to DUX4, whereas involvement of the leg muscles is highly dependent on disease modifying factors.

PS1Group1-110 / #708SCN4A CAN ACT AS MODIFIER GENE IN PATIENTS WITH MYOTONIC DYSTROPHY TYPE 2

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Anna Binda¹, Laura V. Renna², Francesca Bose’², Elisa Brigonzi³, Annalisa Botta⁴, Rea Valaperta⁵, Barbara Fossati⁶, Ilaria Rivolta¹, Giovanni Meola³, Rosanna Cardani⁷

¹School Of Medicine And Surgery, University of Milano Bicocca, Monza, IT;²Laboratory Of Muscle Histopathology And Molecular Biology, IRCCS Policlinico San Donato, San Donato Milanese (MI), IT;³Department Of Biomedical Sciences For Health, University of Milan, San Donato Milanese (MI), IT;⁴Department Of Biomedicine And Prevention, Tor Vergata University of Rome, Rome, IT;⁵Research Laboratories, IRCCS Policlinico San Donato, San Donato Milanese (MI), IT;⁶Department Of Neurology, IRCCS Policlinico San Donato, San Donato Milanese (MI), IT;⁷Laboratory Of Muscle Histopathology And Molecular Biology, IRCCS-Policlinico San Donato, San Donato Milanese (MI), IT

Background: Myotonic dystrophy type 2 (DM2) is caused by a CCTG repeat expansion in intron 1 of the CNBP/ZNF9 gene located on chromosome 3q21. The mutant RNA transcripts containing CCUG repeats alter the activity of specific RNA binding proteins involved in alternative splicing regulation leading to splicing defects that are considered the primary cause of DM1 symptoms. Usually myotonia is mild and inconsistent in DM2 even by electromyography and it has been correlated with the disruption of the alternative splicing of the muscle chloride channel CLCN1. It is noteworthy that mutations in CLCN1 and SCN4A can act as modifier genes in patients with DM2 disease leading to an intensification of their myotonia. We report a 32 years old DM2 patient who presented an atypical phenotype characterized by an early severe myotonia since he was 12 years old. Mexiletine treatment resulted ineffective in reducing myotonia. While no mutation on CLCN1 gene was found, the genetic analysis of SCN4A gene showed a c.2717G>C base exchange in exon 14 predicting an S906T substitution. This variant is considered a benign polymorphism however electrophysiological studies revealed that it affects the fast and slow gating processes. Methods: To investigate the atypical DM2 phenotype of our patient, the combined effects of DM2 mutation and S906T substitution have been studied performing whole-cell patch-clamp in voltage and current clamp mode in myoblasts and myotubes obtained from the skeletal muscle biopsy of the patient. Results have been compared to those obtained in muscle cells derived from his mother, who is also affected by DM2, but did not present the S906T polymorphism. Results: A faster decay of the inactivation kinetics and a +5mV shift in the availability curve (p<0.05) were found in the sodium current recorded in myoblasts derived from the proband compared to his mother. In myotubes showing a stable resting membrane potential, instead, the rheobase current was significantly lower in the proband respect to the mother while the overshoot and the maximum slope of the depolarizing phase of the action potential were higher in the proband respect to the mother. Conclusion: These findings suggest that SCN4A polymorphism may be responsible for a higher excitability of DM2 patients sarcolemma, supporting the severe myotonic phenotype observed. We suggest that SCN4A may be considered a modifier factor and its screening should be performed in DM2 patients with uncommon clinical features.

PS1Group1-111 / #834AAV-SERCA2A EXPRESSION AMELIORATED CARDIOMYOPATHY IN THE MDX MOUSE MODEL OF DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Yongping Yue¹, Nalinda Wasala¹, William Lostal¹, Lakmini Wasala¹, Nandita Niranjan², Roger Hajjar³, Gopal Babu², Dongsheng Duan¹

¹Molecular Microbiology And Immunology (medical Science Bldg), University of Missouri, Columbia, MO, US;²Cell Biology And Molecular Medicine, New Jersey Medical School, Rutgers, The State University of New Jersey, Newark, US;³Mount Sinai School of Medicine, New York, US

Background: Loss of dystrophin leads to Duchenne muscular dystrophy (DMD). Increased cytosolic calcium levels play a critical pathogenic role in the development DMD cardiomyopathy. Cytosolic calcium can be removed by the sarco/endoplasmic reticulum calcium ATPase (SERCA). SERCA activity is reduced in dystrophic muscle. Methods: To test whether SERCA gene transfer can improve calcium recycling and mitigate dystrophic phenotype, we delivered an adeno-associated virus (AAV)-9 SERCA2a vector to 3-m-old mdx mice at the dose of 6E12 viral genome particles/mouse via the tail vein. Whole-body performances were assessed at 8 and 18 months post-treatment using treadmill running and forelimb grip force assays. Serum creatine kinase (CK) activity and heart function (ECG and left ventricular catheterization) were examined at 18 months post-treatment. Results: Western blots and immunostaining confirmed robust SERCA2a expression in heart and skeletal muscle. Forelimb grip strength and treadmill running were significantly improved in treated mice. AAV-9 SERCA2a treatment also reduced the serum CK level, a marker of muscle damage. Importantly, SERCA2a treatment significantly improved heart function. Specifically, all ECG parameters were normalized to the wildtype levels. Several measures of systolic function were normalized in the catheter assay. Treatment also significantly improved ejection fraction, the rate of cardiac relaxation and the end diastolic volume. Conclusion: Our results suggest that AAV-9 SERCA2a gene therapy is a promising approach to treat DMD cardiomyopathy

PS1Group1-112 / #623QUANTITATIVE ANALYSIS OF THIGH MUSCLE BUNDLES OF PATIENTS WITH MYOTONIC DYSTROPHY TYPE 1 (DM1), USING CT IMPAIRMENT RATIO

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Takahiro Nakayama¹, Satoshi Kuru²

¹Department Of Neurology, Division Of Neuromuscular Diseases, Yokohama Rosai Hospital, Yokohama, JP;²Neurology, National Hospital Organization Suzuka National Hospital, Suzuka, JP

Background: It was reported that the atrophy of cervical and thoracic paravertebral, vastus lateral and medial head of gastrocnemius muscle were commonly affected in the patients with myotonic dystrophy type 1 (DM1), however, that the time dependent deterioration had not been confirmed until now. We wanted to know the affected pattern of their thigh muscle and estimating function of their deterioration. Methods: Subjects: CT images of 7 DM1 patients (3 males and 4 females), who were examined once a year, enrolled in this study. Their ages at first visit to hospitals were from 17 to 43, and the number of CTG repeats were from 100 to 1200. Their CT data was collected from 3 to 11 years. Method: The Impairment ratios of each muscle bundle were plotted in each patient as long as possible. The muscle impairment ratio is the ratio of affected muscle fibers in muscle bundles, and calculation formulas were developed by our group. The ratio was determined by following formula, and we used the previously reported CT values of 58 and -98 HU for muscle and fat, respectively. impairment ratio=(“muscle CT value” - “pixel value”)/(“muscle CT value” - “fat CT value”) This investigation was carried out in accordance with the Human Research Guidelines of the Institutional Ethics Review Board of Yokohama Rosai Hospital. Results: In DM1 patients, firstly there is a period of slight muscle impairment. After this period, the muscle ­bundles deteriorate, and this deterioration was well estimated by cumulative normal distribution function. At the end of deterioration stage, we deduced the intermediate vastus thigh muscle is most commonly severely impaired. Most cases felt difficulty to walk at the age when the most affected muscle was impaired 10-20 %. There was no correlation between the CTG repeats and the deterioration. Conclusion: We inferred the muscle will begin to be impaired after the increase of CTG repeats in muscles. The intermediate vastus muscle will be more commonly and more severely affected than surrounding thigh muscles. We concluded that the cumulative normal distribution function was suitable for estimating their muscle deterioration.

PS1Group1-113 / #740LIMB-GIRDLE MUSCULAR DYSTROPHY IN THE CZECH REPUBLIC

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Kristyna Stehlikova¹, Jana Zidkova², Kamila Reblova³, Radim Mazanec⁴, Stanislav Vohanka⁵, Jana Haberlova⁶, Lenka Fajkusova⁷

¹Centre Of Molecular Biology And Gene Therapy, University Hospital Brno, Brno, CZ;²Centre Of Molecular Biology And Gene Therapy, University Hospital Brno, Brno, CZ;³Ceitec, Masaryk University Brno, Brno, CZ;⁴Neurology, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, CZ;⁵Neurology, University Hospital Brno, Brno, CZ;⁶6 Department Of Child Neurology, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, CZ;⁷Masaryk University Brno, Brno, CZ

Background: Limb-girdle muscular dystrophy (LGMD) is a group of disorders, which first affect muscles of the hip and shoulder areas. Genes associated with LGMD normally encode proteins that play vital roles in the muscle function, cell signalling, cell membrane repair, or removal of potentially toxic wastes from cells. 32 genes have been identified so far, 7 with autosomal dominant inheritance (LGMD1) and 25 with autosomal recessive inheritance (LGMD2). LGMD1 is relatively rare and represents less than 10% of all LGMD. LGMD2 is much more common, having a cumulative prevalence of 1:15,000, with some differences among countries. Methods: We per­form molecular genetic diagnostics of neuromuscular disorders (NMD). At present, it is based on gene panel sequencing, pulsed-field gel electrophoresis and Southern analysis (for diagnostics of FSHD1), and repeat-primed PCR (for diagnostics of myotonic dystrophy) in case of muscular dystrophies and myopathies. Differential diagnosis of the LGMD remains quite large and may include LGMD, FSHD, Emery-Dreifuss muscular dystrophy, manifesting carriers of DMD, congenital myasthenic syndromes, congenital myopathies presenting later in childhood or adulthood, and others. Genes associated with mentioned diseases (except FSHD1 which is tested separately) are analysed in parallel with LGMD obligatory genes. Results: We present results of molecular genetic diagnostic of Czech LGMD patients determined by gene panel sequencing (used since 2012) or Sanger sequencing within the gene-by-gene approach (by 2011). In LGMD, we have 166 patients with confirmed genetic diagnosis – 94 patients with variants in CAPN3, 17 patients with variants in FKRP, 14 patients with variants in ANO5, 14 patients with variants in SGCA, 8 patients with a variant in LMNA, 6 patients with variants in DYSF, 4 patients with a variant in CAV3, 3 patients with variants in POMT2, 2 patients with variants in TRIM32, and 1 patient with variants/variant in each of ISPD, SGCG, SGCB, and TNPO3. Conclusion: Besides patients with genetically confirmed LGMD, we have LGMD patients without genetic diagnosis although all so far known muscular dystrophy/myopathy related genes were analysed. These patients are candidates for whole exome sequencing. This study was supported by the project of the Technology Agency of the Czech Republic (TE2000058) and the project of the Grant Agency of the Czech Republic (GA16-11619S/2016).

PS1Group1-114 / #837PULMONARY FUNCTION IN ADVANCED DUCHENNE MUSCULAR DYSTROPHY: ETEPLIRSEN-TREATED PATIENTS VERSUS A NATURAL HISTORY COHORT

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Heather Gordish-Dressman¹, Erik Henricson², Lixin Han³, Ashish Dugar³, Craig Mcdonald², Cooperative International Neuromuscular Research Group (Cinrg)⁴

¹George Washington University School of Medicine and Health Sciences, Washington, DC, US;²University of California Davis, Davis, CA, US;³Sarepta Therapeutics, Inc., Cambridge, MA, US;⁴. US

Background: Eteplirsen is a phosphorodiamidate morpholino oligomer that binds to and excludes exon 51 from dystrophin pre-mRNA, allowing translation and production of internally shortened dystrophin protein. It is approved in the US for treatment of patients with Duchenne muscular dystrophy (DMD) with a confirmed genetic mutation amenable to exon 51 skipping. We evaluated pulmonary function in patients with advanced DMD in a phase 2, open-label, multicenter study of eteplirsen. Methods: Eligible males aged 7-21 years with advanced DMD were enrolled and received once-weekly intravenous eteplirsen 30 mg/kg for 96 weeks. Eligible patients must have been receiving either no corticosteroids or a stable oral corticosteroid dose for ≥24 weeks prior to study entry, with no change in dosage anticipated. Pulmonary function, a predefined exploratory outcome, was assessed by mean change from baseline in percent predicted forced vital capacity (FVC%p). Safety assessments related to pulmonary function included mean change from baseline in respiratory rate (breaths/min) by Week 96. FVC%p outcomes were also evaluated in a Cooperative International Neuromuscular Research Group (CINRG) DMD Natural History Study cohort (patients aged 8-19 years) receiving standard of care treatment with glucocorticoids. Results: Of 24 patients enrolled, 23 (96%) completed 96 weeks of eteplirsen treatment (baseline median age, 13.0 y [range: 8-19]; mean FVC%p, 68.7). Eteplirsen-treated patients had a mean (standard error [SE]) change from baseline in FVC%p of -6.4 (2.16) at Year 1. Mean (SE) change in FVC%p from Year 1 to Year 2 for eteplirsen-treated patients was -0.5 (2.07). Mean respiratory rates were 19.0 at baseline, 20.5 at Week 48, and 20.5 at Week 96 for eteplirsen-treated patients. A comparable CINRG natural history subset (n=10) had similar demographic and clinical characteristics, with mean change in FVC%p of -8.2 over a time frame of 1 year. Conclusion: Eteplirsen treatment slowed the decline of FVC%p in patients with advanced DMD relative to a comparable natural history cohort. The rate of decline for eteplirsen-treated patients slowed most appreciably in Year 2, suggesting a greater impact on disease progression with prolonged eteplirsen treatment.

PS1Group1-115 / #931CLINICAL OUTCOME STUDY OF DYSFERLINOPATHY: TEENAGE EXERCISE AS A POTENTIAL MODIFIER OF DISEASE SEVERITY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Claudio Semplicini¹, Ursula Moore², Marni Jacobs³, Roberto Fernández-Torrón⁴, Jiji Jang³, Meredith James², Anna Mayhew², Laura Rufibach⁵, Plavi Mittal⁵, Michele Eagle², Avital Cnaan⁶, Pierre G. Carlier⁷, Andrew Blamire⁸, Heather Hilsden², Hanns Lochmuller², Ulrike Grieben⁹, Simone Spuler¹⁰, Carolina Tesi Rocha¹¹, John W. Day¹¹, Kirsti J. Jones¹², Diana X. Bharucha-Goebel¹³, Emmanuelle Salort-Campana¹⁴, Matthew Harms¹⁵, Alan Pestronk¹⁵, Sabine Krause¹⁶, Olivia Schreiber-Katz¹⁶, Maggie C. Walter¹⁶, Carmen Paradas¹⁷, Jean-Yves Hogrel¹⁸, Tanya Stojkovic¹⁹, Shin’Ichi Takeda²⁰, Madoka Mori-Yoshimura²¹, Elena Bravver²², Susan Sparks²², Jordi D. Manera²³, Luca Bello²⁴, Elena Pegoraro¹, Jerry R. Mendell²⁵, Kate Bushby², Volker Straub²⁶

¹University of Padova - Azienda Ospedaliera di Padova, Padova, IT;²The John Walton Muscular Dystrophy Research Centre, Newcastle Hospitals Trust, Newcastle University, Newcastle Upon Tyne, GB;³Division Of Biostatistic And Study Methodology, Children’s National Health System, Centre for Translational Science, DC, WA, US;⁴Neuromuscular Area, Biodonostia Health Research Institute, Neurology Service, Donostia University Hospital, Donostia University Hospital, Donostia-San Sebastian, ES;⁵Jain Foundation, Seattle, US;⁶Pediatrics, Epidemiology And Biostatistics, George Washington University, Washington DC, US;⁷Aim & Cea Nmr Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, FR;⁸Magnetic Resonance Centre, Institute For Cellular Medicine, Newcastle University, Newcastle Upon Tyne, GB;⁹Charite Muscle Research Unit, A Joint Cooperation Of The Charité Medical Faculty And The Max Delbrück Center For Molecular Medicine, Experimental and Clinical Research Center, Berlin, DE;¹⁰Charite Muscle Research Unit, Experimental and Clinical Research Center, Berlin, DE;¹¹Department Of Neurology And Neurological Sciences, Stanford University School of Medicine, Stanford, CA, US;¹²Institute For Neuroscience And Muscle Research, Children’s Hospital At Westmead, University of Sydney, Sydney, AU;¹³Department Of Neurology, Children’s National Health System, Washington DC, US;¹⁴Neuromuscular And Als Center, La Timone Hospital, Aix-Marseille Universite, Marseille, FR;¹⁵Department Of Neurology, Washington University School of Medicine, St. Louis, MO, US;¹⁶Friedrich-baur Institute, Departement Of Neurology, Ludwigs-Maximilians University of Munich, Munich, DE;¹⁷Neuromuscular Unit, Department Of Neurology, Hospital U. Virgen del Rocio/Instituto de Biomedicina de Sevilla, Sevilla, ES;¹⁸Institut De Myologie, Boulevard de l’Hôpital, Paris, FR;¹⁹Ap-hp, G.h. Pitié-salpêtrière 47-83, Boulevard De L’hôpital, Institut de Myologie, Paris, FR;²⁰National Center of Neurology and Psychiatry, Tokyo, JP;²¹Department Of Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Tokyo, JP;²²Carolinas Healthcare System Neurosciences Institute, Charlotte, NC, US;²³Neuromuscular Unit, Neurology Department, Hospital de la Santa Creu i Sant Pau, Barcelona, ES;²⁴Department Of Neuroscience, University of Padova, Padova, IT;²⁵Center for Gene Therapy Nationwide Children’s Hospital, Columbus, US;²⁶John Walton Muscular Dystrophy Research Centre, Newcastle University, Institute of Genetic Medicine, Newcastle Upon Tyne, GB

Background: The Clinical Outcome Study of Dysferlinopathy (COS) is an international 3 year natural history study of dysferlinopathy patients. Dysferlinopathy, a genetic muscular dystrophy caused by DYSF mutations, demonstrates a variable age of presentation and progression rate, suggesting disease modifying factors. Here we investigate teenage exercise intensity and subsequent disease progression in 182 patients. Methods: Participants were asked about the type, level and frequency of all physical activity prior to symptom onset. Self-reported age of first symptoms, first wheelchair use and full-time wheelchair use was taken from screening questionnaires. Exercise was classified based on metabolic equivalents (METs) as moderate (MET 3–6) or vigorous (MET >6). Participants were coded, based on the maximum frequency of activity reported between ages 10 and 18 years, as 0—no physical activity; 1—vigorous activity occasionally/monthly, or moderate activity once weekly; 2— moderate activity multiple times per week or vigorous activity once weekly; and 3—vigorous activity multiple times per week. Age of symptom onset was compared by analysis of variance (ANOVA) with least squares means for individual group differences. Risk of symptom onset, occasional wheelchair use and full-time wheelchair requirement over time were compared for exercise groups 1, 2 and 3 against group 0 using Cox proportional hazards regression. Interaction between teen exercise level, gender and clinical diagnosis was also assessed by two-way ANOVA. Subgroups of limb girdle muscular dystrophy 2B (LGMD2B), Miyoshi myopathy (MM) or ‘other’ (all genetically confirmed dysferlinopathies) were used for analysis. Results: Estimated mean age of symptom onset differed by group (P=0.03) and was later in group 0 (mean 24.8 years; 95% CI 22.3 to 27.2 years) compared with groups 2 (mean 20.2 years; CI 18.1 to 22.3 years, P=0.006) and 3 (mean 20.6 years, CI 18.4 to 22.8 years, P=0.01), but not group 1 (mean 21.7years; CI 17.7 to 25.7 years, P=0.20). Cox regression analysis suggested that groups 2 (Hazard ratio 1.56 95% CI 1.06 to 2.30)) and 3 (Hazard ratio 1.54 (1.04 to 2.30)) were at increased risk of earlier symptom onset than group 0 (figure 1). This was not significant for group 1 (Hazard ratio R 1.38 (0.78 to 2.45)). Conclusion: This study raises implications for early diagnosis and clinical care, however as we did not look at the effects of exercise once symptoms began, we would not advocate that symptomatic patients stop exercising.

PS1Group1-116 / #507GLYCOGENOSIS TYPE V (MCARDLE DISEASE): THERAPY WITH VITAMIN B6

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Annika Saak, Heinz Reichmann, Jochen Schaefer

Neurology, University Hospital Dresden, Dresden, DE

Background: The glycogen storage disease type V or McArdle disease is one of the metabolic myopathies and is characterized by a stress intolerance with myalgia, myopathy and muscle cramps. The autosomal-recessive disorder is in Europe usually caused by a stop mutation (P-R50X) in the PYGM gene. There is no causal form of therapy so far, so that patients are advised of symptomatic therapy with creatine or cane sugar before physical exertion. Positive effects of vitamin B6 on the subjective muscular resilience have been described in individual case reports. Our patient, in which a previously undescribed genetic defect (c. 1456G > A) could be detected in the PYGM gene, was treated with vitamin B6 for over 4 years. The subjective improvement reported by the patient should be clinically and laboratory-chemically objectified. Methods: We performed recurrent clinical examinations to find a subjective symptom improvement. In addition, the laboratory-chemical determination of the lactate and ammonia with and without vitamin B6 therapy was carried out during the work test with 2-minute ischemia. Results: The patient reports a progressive improvement in muscular strength and endurance and negates myalgia under the vitamin B6 therapy. A doubling of the walking distance could be achieved under vitamin B6. Under the vitamin B6 substitution occurred a drawdown of the creatine kinase. In the work test with vitamin B6 supplementation exposed a normal increase in lactate and ammonia, while without vitamin B6 only a slight increase in lactate was recorded. Conclusion: We report on a patient with a previously undescribed homozygous, pathogenic mutation in the PYGM gene, which is located in the vicinity of the PLP binding site of the myophosphorylase and thus explains the good response to vitamin B6. The daily substitution of vitamin B6 could help to improve clinical and laboratory chemical muscular symptoms. In our view, a therapy attempt seems justified in the case of low costs and side effects of vitamin B6 in the case of proven McArdle disease, particularly in the case of a mutation in the immediate vicinity of the PLP binding site of the myophosphorylase.

PS1Group1-117 / #782MASSIVE INCREASE IN CARDIAC TROPONIN T WITHOUT CARDIAC INVOLVEMENT IN NECROTIZING MYOPATHY WITH ANTI-HMGCR-ANTIBODIES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Annika Saak¹, Jochen Schaefer², Sandra Jackson²

¹Neurology, University Hospital Dresden, Dresden, DE;²Neurology, University Hospital Dresden, Dresden, DE

Background: Immune-mediated necrotizing myopathies may be caused by antibodies to anti-SRP or anti-HMG CoA reductase. They are characterized by muscle weakness, pronounced hyperCKemia and myalgias and may be associated with malignancies. Therapeutically, various immunosuppressants such as steroids, immunoglobulins or cytotoxic drugs are used. Methods: A 19-year-old statin-naïve patient developed acute tetraplegia with muscle tenderness and high antibody titers to HMG-CoA reductase. Besides marked hyperCKemia (up to 308μCat / L; norm<3.2) a massive increase in cardiac troponin T (up to 2580 ng / L; norm <14) was noted in the absence of overt cardiac involvement. A musculoskeletal origin of cardiac troponin T was suspected.We determined cardiac troponin T (cTnT) and cardiac troponin I (cTnI) under various therapeutic regimens and investigated for cardiac involvement due to the underlying necrotizing myopathy. In addition, the expression of cTnT and cTnI is currently being analyzed in undifferentiated (myoblasts) and differentiated (myotubes) cultured muscle cells. Results: Extensive cardiac diagnostic investigations (ECG, TTE, cardiac CT and MRI, heart rate variability) were unremarkable. However, despite massively elevated cTnT levels, cardiac troponin I values always remained normal. Alongside the clinical improvement under intravenous immunoglobulin therapy, there was a concomitant decrease in creatine kinase, cTnT and anti-HMG-CoA reductase antibody titers. Conclusion: We report a statin-naive patient with severe anti-HMGCR-positive necrotizing myopathy, who had massively elevated cTnT levels. After exclusion of cardiac involvement, which was corroborated by normal concentrations of the entirely cardiospecific cTnI, we interpret the massive increase of cTnT in the patient as of exclusively musculoskeletal origin. Although cTnT may be mildly elevated (10fold) in various myopathies, it has – to our knowledge – not been described to rise to such an extent (200fold) in myopathies without cardiac involvement. Compared to mature myocytes, HMGCR expression is up-regulated in regenerating muscle fibres which may therefore undergo an accelerated turnover in an anti-HMGCR-positive necrotizing myopathy. Moreover, some evidence suggests that cTnT which is expressed only in low amounts in mature myocytes, is expressed in much higher amounts in regenerating skeletal muscle cells, thus explaining particularly high levels of cTnT in our patient. This is to be verified in muscle cell cultures at various stages of differentiation.

PS1Group1-118 / #688RESULTS OF NORTH STAR AMBULATORY ASSESSMENTS IN  THE ACT DMD TRIAL IN IN PATIENTS WITH NMDMD

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Francesco Muntoni¹, Panayiota Trifillis², Gary L. Elfring², Stuart W. Peltz³, Craig Mcdonald⁴

¹Dubowitz Neuromuscular Unit, UCL Great Ormond Street Institute of Child Health, London, GB;²PTC Therapeutics, Inc, South Plainfield, NJ, US;³PTC Therapeutics Inc, South Plainfield, NJ, US;⁴Physical Medicine And Rehabilitation, UC Davis Medical Center, Sacramento, CA, US

Background: Ataluren is the first drug to treat the underlying cause of nonsense mutation Duchenne muscular dystrophy (nmDMD) by promoting readthrough of a premature stop codon to produce full-length functional dystrophin. ACT DMD was a phase 3, randomized, double-blind, placebo-controlled trial of ataluren that enrolled males aged 7–16 years with nmDMD and baseline six-minute walk distance (6MWD) ≥150m and ≤80%-predicted. Methods: Eligible patients were randomized 1:1 to receive ataluren 10, 10, 20 mg/kg or placebo orally three times daily for 48 weeks. The NSAA is a validated functional scale to measure disease progression specifically in ambulant boys with DMD. It consists of 17 activities ranging from standing from a chair to jumping. Each activity is scored as 0, 1, or 2; the sum of these 17 scores forms the total score, which is linearized to a 0 (worst)-100 (best) score. The intent-to-treat population of ACT DMD consisted of 228 patients (ataluren, n=114; placebo, n=114). Results: Overall, patients who received ataluren gained a 1.5-point advantage in NSAA observed score compared with patients who received placebo (mean NSAA scores, ataluren: -7.0; placebo: -8.5; p=0.270). In addition, fewer patients who received ataluren shifted from a score of 1 or 2 (able to perform function) to 0 (unable to perform function) across all 17 activities compared with those who received placebo. Between-group differences across each of the 17 activities consistently favored ataluren, ranging from 1% (lift head) to 11% (jump) to 12% (rise from chair). Conclusion: In conclusion, ataluren is the first drug to demonstrate a benefit to patients with nmDMD compared with placebo as assessed by NSAA scores.

PS1Group1-119 / #932NONSENSE AND SINGLE NUCLEOTIDE FRAMESHIFT MUTATIONS IN BECKER MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Monica Traverso¹, Chiara Panicucci¹, Michela Catteruccia², Paolo Broda¹, Francesca Madia³, Giulia Pozzolini³, Maria Derchi⁴, Annalaura Torella⁵, Claudio Bruno⁶, Federico Zara³, Vincenzo Nigro⁵, Carlo Minetti¹, Adele D’Amico², Chiara Fiorillo⁷

¹Pediatric Neurology And Muscular Disorders, Gaslini Children Hospital, Genoa, IT;²Unit Of Neuromuscular Disorders, Laboratory Of Molecular Medicine, Bambino Gesu’ Children’s Hospital,, Rome, IT;³Neurogenetic Laboratory, University of Genoa-Gaslini Children Hospital, Genoa, IT;⁴Cardiology, University of Genoa-Gaslini Children Hospital, Genoa, IT;⁵Precision Medicine, Università degli Studi della Campania “Luigi Vanvitelli”, Naples, IT;⁶Centre Of Myology, University of Genoa-Gaslini Children Hospital, Genoa, IT;⁷Neuroscience, University of Genoa, Genoa, IT

Background: Nonsense and frameshift mutations in DMD gene potentially determine the interruption of protein synthesis and degradation of a truncated dystrophin, for this reason they are usually associated with severe Duchenne phenotype (DMD). Conversely, in-frame mutations lead to reduced or abnormal protein synthesis and are associated to milder Becker muscular dystrophy (BMD). Exceptions of this rule are found in a small percentage of cases. In these uncommon cases, the exact location of the mutation is considered an important factor. Nevertheless other factors, such as presence of splicing regulatory elements, can influence the ultimate outcome and they are largely unexplored in routine diagnostic procedures. Methods: We present clinical, molecular and immunohistochemistry study of a sample of 9 Italian BMD patients (age range 7-30 years) carrying nonsense or single nucleotide mutations in DMD gene. Patients were evaluated with North-Star Ambulatory Assessment (NSAA) and muscle MRI. Muscle biopsies were obtained from 8 cases. Routine histological procedures, immunofluorescence and western blot were performed. We also analysed the specific transcripts involving the different mutations via RT-PCR. Results: Most mutations are nonsense, localised between exon 1-29 and in exon 74. One mutation is a splice site variant leading to absence of exon 11 and subsequent loss of reading frame. Another mutation is a single nucleotide duplication leading to downstream frameshift in exon 73. Six mutations are described and have been associated either with DMD or BMD. Three variants are novel. From a clinical point of view, all patients are still ambulant, however 4 presented moderate phenotype (NSAA below 30) and the oldest patient was not able to rise from the floor autonomously. CK was significantly elevated (range 3000-15000 U/l, normal value < 200). The 2 oldest patients also displayed signs of heart involvement and were in therapy with ACE inhibitors. No patient was taking corticosteroids. Muscle sections showed variable degree of necrosis and degeneration of muscle fibres, which correlates with age at biopsy and CK level. Dystrophin expression was only partially reduced with immunofluorescence from moderate severe, to mild reduction. Interesting in most patients staining for alpha-dystroglycan was also markedly reduced. Western blot showed either absent dystrophin or reduced amount of protein of normal size. In three cases a lower weight dystrophin band was detected with Western Blot. RT-PCR documented presence of normal size products in nonsense mutations and of shorter products in the case of splice site mutation. Conclusion: In this small cohort, we observed nonsense and single nucleotide frameshift mutations in BMD patients, few presenting a moderate phenotype when compared with the most common BMD patient with multiple exon deletions. Additionally, we showed that dystrophin mRNA and protein are still retained in affected muscles, suggesting an altered function of the protein. We argue that this can be highlighted by marked reduction of the distrophyn-dystroglycans complex. These cases underscore the importance of a complete analysis of DMD gene and its transcript in order to provide better prognostic information and genotype-phenotype correlation. Additionally presence of nonsense mutations in BMD patients raise question on the possible therapeutic approaches.

PS1Group1-120 / #959DEVELOPMENT OF A PROGNOSTIC MODEL FOR 1-YEAR CHANGE IN TIMED 4 STAIR-CLIMB IN DUCHENNE PATIENTS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Nathalie Goemans¹, Marleen Vanden Hauwe¹, James Signorovitch², Gautam Sajeev², Zhiwen Yao², Madeline Jenkins², Erin Mcdonald², Imbrahima Dieye², Susan J. Ward³

¹Neuromuscular Reference Centre, Department Of Paediatrics And Child Neurology, University Hospitals Leuven, Leuven, BE;²Analysis Group, Boston, US;³cTAP, Cambridge, US

Background: Longitudinal progression of disease is inherently heterogeneous among individuals with Duchenne muscular dystrophy (DMD). The resulting variation in outcome measures can complicate clinical trial design and potentially cloud interpretation of results. The collaborative Trajectory Analysis Project (cTAP) is a pre-competitive coalition of academic clinicians, drug developers, and patient foundations; cTAP was formed in 2015 to identify biostatistical approaches to overcome the challenges of high variation in clinical trials in DMD. We previously reported a prognostic score that explained 60% of variation in the change in 6 minute walk distance (6MWD) over 1 year, and significantly improved upon prognosis from baseline age, 6MWD and steroid use by also incorporating timed function tests, height and weight [Goemans N, vanden Hauwe M, Signorovitch J, Swallow E, Song J, CollaborativeTrajectory Analysis Project (cTAP) (2016). Individualized Prediction of Changes in 6-Minute Walk Distance for Patients with Duchenne Muscular Dystrophy. PLoS ONE 11(10): e0164684. doi:10.1371/journal.pone.0164684] The aim of the present study was to develop a prognostic model for 1-year change in 4-stair climb (4SC) among DMD patients, and to assess the additional predictive value of the model compared to commonly used factors (i.e., age, baseline 6MWD and steroid use). Methods: Natural history data were collected from DMD patients approximately every 6 months over the course of 2 to 5 years during routine clinical practice at the Universitaire Ziekenhuizen pediatric neurology clinic in Leuven, Belgium. Patient demographics, treatment experience and ambulatory outcomes were recorded at each visit. Annualized changes in 4SC were studied between all pairs of visits separated by ~1 year (8-16 months). Prediction models were developed using multivariable regression for repeated measures. Generalized estimating equations (GEE) with an exchangeable covariance structure were used to account for the use of multiple pairs of visits from individual patients. Results: A total of n=235 ~1-year follow-up intervals from n=81 boys were included. Mean age was 9.1 years and mean 4-SC was 3.84 s at the start of these intervals; average duration of steroid use was 29.11 months. During the subsequent ~1-year, mean annualized change in 4SC was 0.71 s with a standard deviation (SD) of 2.20. Predictions based on age, baseline 4SC and steroid use explained 13% of variation in annualized 4SC changes (R-squared = 0.13). A broadened prognostic model, adding timed 10-meter walk/run, and rise from supine, as well as height and weight, significantly improved prediction, explaining 34% of variation in annualized 6MWD changes (R-squared=0.34). In the broadened model, parameters that were most strongly correlated with 1 year change in 4SC were steroid use > 1 year (p <0.001), baseline 4SC (s)(p < 0.001), baseline rise from supine (s)(p < 0.001) and baseline 10 meter walk run (s) (p<0.05). Conclusion: A prognostic model incorporating timed function tests significantly improved prediction of 1-year changes in 4SC. Explained variation was more than doubled compared to predictions based only on age, baseline 4SC and steroid use, indicating significant potential for broader prognostic models to inform clinical trial design and interpretation in DMD

PS1Group1-121 / #989AMBULATORY ELECTROCARDIOGRAPHIC LONGITUDINAL STUDY IN THE GRMD DOG MODEL OF DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Inès Barthélémy, Xavier Cauchois, Stephane Blot

U955 - Imrb, Inserm, Ecole Nationale Vétérinaire D’alfort, Upec, U955 - IMRB, Inserm, Ecole Nationale Vétérinaire d’Alfort, UPEC, Maisons-Alfort, FR

Background: Duchenne muscular dystrophy (DMD) is a progressive muscle disease leading to motor, respiratory and cardiac disabilities. Electrocardiographic (ECG) monitoring is part of the standards of care for DMD patients, and reveals tachycardia, elongated QT, deep Q-waves, premature ventricular beats (PVBs), and early decreased heart rate variability (HRV). The preclinical research of treatments targeting DMD is supported by a translational chain, which ultimate link is the GRMD dog (Golden Retriever Muscular Dystrophy), since it faithfully reproduces the DMD disease course in a large animal context. This includes the occurrence of a cardiomyopathy, with onset of myocardial fibrosis in the 6-12 months of age period, followed by a decrease of heart contractility, and ultimately in some dogs a death from decompensated dilated cardiomyopathy. Since this model is used at the very last preclinical step, there is a need to evaluate the effect of candidate treatments using methods analog to those used in patients. Few studies have focused on ECG in GRMD, but no one longitudinally using ambulatory Holter recordings, and investigating HRV. We aimed to describe the sequential ECG alterations in GRMD dogs in order to provide relevant indices to be used in preclinical studies. Methods: Holter ECG recordings were performed monthly overnight in 15 GRMD and 4 healthy littermates from the age of 2 months until the age of 24 months. The lead II was used for quantitative analysis, which first focused on four timepoints: 6, 12, 18, and 24 months of age. The heart rate, QT interval, Q/R ratio, and the occurrence of arrythmias were quantified. A HRV analysis was also performed including time-domain analysis and frequency domain analysis. Results: One of the 4 healthy dogs presented an increased heart rate, a markedly reduced HRV, and had transiently elevated serum cTpnI. We thus chose to exclude this dog from the analysis. The heart rate was found increased in GRMD dogs, this difference being significant from the age of 12 months. There was a trend towards elongated QT at 24 months. We found a significantly increased Q/R ratio only at the age of 6 months. PVBs were observed in 5 over the 8 dogs at 24 months of age. Two of them already presented such arrhythmias at 6 months of age, and most of the others started to exhibit PVBs between 12 and 18 months of age. These PVBs were polymorphic in two dogs, and could be seen either isolated, in doublets or triplets; transient episodes of ventricular tachycardia could also be detected. HRV analysis revealed significantly decreased pNN50 at 12 months of age, and a decrease of the LF/HF ratio from the age of 12 months. Conclusion: This study provides new indices to monitor the cardiac disease in GRMD dogs, and again demonstrates similarities between GRMD and DMD cardiomyopathies. These similarities and the availability of a comprehensive evaluation set including ECG, echocardiography, cardiac NMRI, paralleling the one used in DMD patients, make the GRMD dog an optimal context to anticipate therapeutic effects expectable in DMD patients, measured with the same tools and indicators.

PS1Group1-122 / #652MIMICS OF INCLUSION BODY MYOSITIS: CASE PRESENTATIONS AND IDENTIFICATION OF TYPICAL PITFALLS

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Rachel Zeng, Stefanie Glaubitz, Karsten Schmidt, Per-Ole Carstens, Jens Schmidt, Jana Zschüntzsch

Department Of Neurology, University of Göttingen, Göttingen, DE

Background: Inclusion body myositis (IBM) is an idiopathic inflammatory myopathy with typical clinical symptoms und histological features. However, due to a range of acquired or genetically determined myopathies with similar presentations, IBM is often missed and diagnosed in error as another neuromuscular disease. Methods: Along with dermatomyositis, polymyositis, overlap myositis and (immune mediated) necrotizing myopathy, IBM belongs to the group of idiopathic inflammatory myopathies (IIM). The typical clinical presentation of IBM involves slowly progressive muscle atrophy and weakness with a preference of long finger flexors, knee and foot extensors, often with an asymmetric distribution. Other symptoms may include myalgia and dysphagia, the latter reported in over the half of the patients with IBM. The diagnosis of IBM is currently based on a defined composition of clinical, serological and muscle histologic criteria. Additionally, electromyography, muscle MRI and muscle ultrasound may help to confirm the diagnosis. A muscle biopsy is required to diagnose a clinico-pathologically defined IBM, showing the co-existence of myodegenerative and inflammatory pathologic features. Nevertheless, the diagnosis of IBM or the differentiation from other neuromuscular diseases can be difficult due to atypical clinical presentations. Histopathological findings can also lead to confusion since inflammatory infiltrates can also be found in hereditary myopathies like dysferlinopathy or facioscapulohumeral dystrophy. The myodegenerative characteristics of myofibrillar myopathies like vacuoles and abnormal accumulations of filamentous proteins can also be mistaken. Only a correct and reliable diagnosis of IBM allows for recruitment to clinical studies and helps to find novel, exploratory treatment modalities and prevent unnecessary treatments. Results: Here, we provide typical case reports of hereditary inclusion body myopathy (hIBM), titinopathy (TMD/LGMD2J), facioscapulohumeral muscular dystrophy (FSHD), polymyositis, chronic inflammatory axonal polyneuropathy (CIAP) and other neuromuscular diseases that can mimic IBM. Conclusion: The data are ­carefully discussed and typical clinical pitfalls are summarized.

PS1Group1-123 / #690LONG-TERM PULMONARY FUNCTION  IN NON-AMBULATORY PATIENTS WITH NMDMD TREATED WITH ATALUREN

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Craig Mcdonald¹, Eugenio Mercuri², Francesco Muntoni³, Kathryn Selby⁴, Fengbin Jin⁵, Gianina Panaghie-Meltzer⁶, Panayiota Trifillis⁵, Marcio Souza⁶, Stuart W. Peltz⁶, Mar Tulinius⁷

¹Physical Medicine And Rehabilitation, UC Davis Medical Center, Sancramento, CA, US;²Università Cattolica del Sacro Cuore, Rome, IT;³Dubowitz Neuromuscular Unit, UCL Great Ormond Street Institute of Child Health, London, GB;⁴British Columbia Children’s Hospital, Vancouver, BC, CA;⁵PTC Therapeutics, Inc, South Plainfield, NJ, US;⁶PTC Therapeutics Inc, South Plainfield, NJ, US;⁷Gothenburg University, Gothenburg, SE

Background: Duchenne muscular dystrophy (DMD), an X-linked, recessive disease affecting ~ 1 in every 3600–6000 live male births, is caused by dystrophin gene mutations. Dystrophin is critical for myofiber structural stability and function; its absence leads to progressive muscle dysfunction, loss of ambulation, and early death from respiratory/cardiac failure. Forced vital capacity (FVC) < 1 L raises mortality risk in DMD patients. About 10–15% of patients have a dystrophin gene nonsense mutation (nonsense mutation DMD [nmDMD]), where a premature stop codon halts translation to generate truncated, nonfunctional dystrophin. Ataluren promotes ribosomal readthrough of the premature stop codon to produce a full-length dystrophin protein, treating the underlying cause of nmDMD. Methods: FVC data from non-ambulatory patients at study entry (unable to run/walk 10 m in ≤ 30 seconds) aged 9 to 18 years receiving oral ataluren (40 mg/kg/day [10, 10, and 20 mg/kg for morning, midday and evening doses, respectively]) were obtained from Study 019 (NCT01557400; begun in 2012; data cut-off Jan. 31, 2017), an international, multicenter, open-label trial that enrolled patients from previous ataluren PTC-sponsored trials at non-US study sites. Data for age-matched, non-ambulatory patients (wheelchair-bound) in subjects receiving SOC (not ataluren) were obtained from an ongoing natural history study (CINRG, NCT00468832; from 2012 through Nov.18, 2016) and compared to 019 FVC < 1L by Kaplan-Meier analysis. Results: Subgroups included 38 ataluren- and 58 SOC-treated patients. At data cut-off fewer ataluren-treated vs SOC-treated patients had FVC <1 L (7.9% vs 39.7%, respectively). FVC < 1L was reached by 50% of SOC-treated patients by age) age 19.3 years (95% CI, 18.8–22.6). At age 19.3 years, only 16% of ataluren-treated patients had FVC < 1 L. FVC <1L was reached by 50% of SOC-treated patients after 7.1 years (5.3–9.4) with SOC (log-rank test p = 0.067); 10% of ataluren-treated patients had FVC <1L after 4 years. Most adverse events (AEs) on ataluren were mild (29.5% of patients) or moderate (31.8% of patients). The most common AEs were nasopharyngitis (45.5%), headache (27.3%), vomiting (27.3%), and gastroenteritis (22.7%). Conclusion: Findings suggest that ataluren preserves lung function in non-ambulatory patients with nmDMD. Safety and tolerability were consistent with previous findings.

PS1Group1-124 / #701USE OF A >/= 5-SECOND THRESHOLD IN BASELINE TIME TO STAND FROM SUPINE TO PREDICT PROGRESSION IN DMD

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Craig Mcdonald¹, Marcio Souza², Gary L. Elfring³, Panayiota Trifillis³, Joseph Mcintosh², Stuart W. Peltz², Eugenio Mercuri⁴

¹Physical Medicine And Rehabilitation, UC Davis, Sacramento, CA, US;²PTC Therapeutics Inc, South Plainfield, NJ, US;³PTC Therapeutics, Inc, South Plainfield, NJ, US;⁴Università Cattolica del Sacro Cuore, Rome, IT

Background: Time to stand from supine is a predictor for loss of clinically meaningful Duchenne muscular dystrophy (DMD) milestones. A ≥5-second threshold in this functional test can predict disease progression over 48 weeks; conversely, a <5-second threshold suggests functional stability. This analysis examined the usefulness of a ≥5-second threshold as a subset analysis for DMD trials. Methods: A post hoc analysis was conducted using data from the subset of patients with a baseline time to stand from supine ≥5 seconds from two 48-week, randomized controlled trials examining the efficacy and safety of ataluren in patients with nonsense mutation DMD: a phase 2b (Study 007/NCT00592553; boys ≥5 years) and a phase 3 trial (Study 020/NCT01826487; boys ≥7–≤16 years). Results: In Study 007, 37 ataluren- and 29 placebo-treated patients met the ≥5-second threshold. Their respective mean (standard deviation, SD) baseline 6-minute walk distances (6MWD) were 311.3 (91.1) and 312.2 (82.2) m. In Study 020, 56 ataluren- and 46 placebo-treated patients met the ≥5-second threshold: mean (SD) baseline 6MWD, 349.9 (60.2) vs 336.6 (63.8) m, respectively. A beneficial ataluren response vs placebo was observed across multiple endpoints in both trials in the ≥5-second threshold subgroup. Study 007 (ataluren vs placebo, respectively); 48-week change in: 6MWD (–35.9 vs –85.6 m, p=0.01), 10-m run/walk (2.5 vs 5.1 seconds, p=0.10), 4-stair climb (3.5 vs 7.5 seconds, p=0.02). Study 020 (ataluren vs placebo, respectively); 48-week change in: 6MWD (–48.7 vs –100.1 m, p<0.01), 10-m run/walk (2.3 vs 4.8 seconds, p=0.03), 4-stair climb (4.7 vs 7.6 seconds, p=0.04). Conclusion: Consistent with published natural history data, placebo-treated patients with a baseline time to stand from supine ≥5 seconds showed declining ambulatory ability over 48 weeks. A ≥5-second threshold may represent a useful subset analysis for DMD trials; this post hoc analysis highlights an ataluren treatment benefit vs placebo.

PS1Group1-125 / #780NOVEL THERAPEUTIC PERSPECTIVES FOR SARCOGLYCANOPATHY, IN VITRO AND IN VIVO STATE OF THE ART

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Dorianna Sandona¹, Roberta Sacchetto², Elisa Bianchini², Marcello Carotti², Michela Soardi³, Chiara Fecchio⁴

¹University of Padova, Padova, IT;²university of padova, Padova, IT;³university of padova, padova, IT;⁴Biomedical Science, University of Padova, Padova, IT

Background: Sarcoglycans (SG) are glycosylated proteins (alpha-, beta-, gamma- or delta-SG) forming a key structural complex, essential for the sarcolemma integrity of striated muscles during contraction. In sarcoglycanopathies, defects in any one of the sarcoglycan genes lead to the strong reduction or even the loss of the SG-complex. Most of the reported cases are due to missense mutations originating a full length but folding-defective proteins. We proved that the primary pathological event in sarcoglycanopathy occurs in the Endoplasmic Reticulum, where the quality control system, by proof-reading newly synthesized sarcoglycans, recognizes and delivers to proteasomal degradation the folding-defective mutants. This results in the secondary loss of the wild-type partners. We also observed that many missense mutants retain their function as the entire complex can be properly rescued by reducing the mutant degradation. These findings opened new therapeutic perspectives for this neglected disease allowing to design small molecule-based approaches aimed either to inhibit sarcoglycan mutants degradation, or to help their folding so that, skipping disposal, they can assemble and traffic at the proper site of action. Methods: Culture and differentiation of primary myogenic cells of LGMD2D patients. Biochemical and molecular analysis of sarcoglycan expression. Primary myotubes treatment with small molecules. AAV transduction of newborn alpha-SG KO mice. CRISPR-Cas9 genome editing of zebrafish. Results: We tested several small molecules known as CFTR correctors which successfully recovered different mutants of alpha-sarcoglycan in cellular models and, notably, the whole SG-complex in primary myotubes from a patient suffering of alpha-sarcoglycanopathy. Moreover, we performed a functional test by measuring CK release from patient’s myotubes under stressful conditions, showing membrane stabilization when cells were pretreated with CFTR correctors. Interestingly, cytotoxicity tests highlighted absent or low toxicity of these compounds on cells. To confirm in vivo this successful strategy we need animal models expressing folding-defective sarcoglycans. As the available SG-KO and KI mice are unsuitable to our purposes, and considering the large number of reported sarcoglycan missense mutants, our aim is now the generation and characterization of novel and unconventional alpha-sarcoglycanopathy vertebrate models. To this purpose, we have planned to generate transiently “humanized” mice, by the transduction of the null mice with rAAVs (recombinant adeno associated viruses) expressing different missense mutants of the human alpha-SG. On the other hand, we are focusing on the small vertebrate zebrafish, also considering that the available SG KI mice failed to develop a dystrophic phenotype. Taking advantage of state of the art genome editing techniques such as the CRISPR-cas9 system, we have obtained the beta- and delta-SG KO lines, at present under characterization, whereas the generation of SG KI zebrafish is ongoing. Conclusion: While mice are usually the vertebrate model of election for pharmacological studies, zebrafish represents a valuable and recognized vertebrate for modelling muscle diseases and presents advantages over mammals especially for quicker and wider drug screening procedures. Together, these two complementary approaches will allow us to evaluate efficacy and safety of the promising molecule identified in vitro and will foster the development of a cure for sarcoglycanopathy.

PS1Group1-126 / #807ATALUREN IN PATIENTS AGED ≥ 2 TO <5 YEARS WITH NMDMD: 28-WEEK RESULTS FROM A PHASE 2 STUDY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Cuixia Tian¹, Robert Kong², Fengbin Jin³, Edward O’Mara³, Panayiota Trifillis³, Joseph Mcintosh², J B. Renfroe⁴

¹Neurology, Cincinnati Children’s Hospital Medical Center, Cincinatti, OH, US;²PTC Therapeutics Inc, South Plainfield, NJ, US;³PTC Therapeutics, Inc, South Plainfield, NJ, US;⁴Child Neurology Center of NW Florida, Gulf Breeze, FL, US

Background: Nonsense mutation Duchenne muscular dystrophy (nmDMD) is a rare, X-linked genetic disorder that relts in a progressive decline in function, loss of ambulation and early death due to respiratory or cardiac complications. Ataluren enables production of full-length dystrophin protein by promoting ribosomal readthrough of a premature stop codon in the mRNA transcribed from the dystrophin gene. The goal of dystrophin restoration therapy is to slow or stabilize disease progression in patients with nmDMD. Ataluren is conditionally approved by the European Medicines Agency for the treatment of ambulatory patients aged ≥ 5 years with nmDMD. Initiation of ataluren therapy for dystrophin restoration at a younger age, prior to substantive muscle loss, may maximize its therapeutic benefit. Methods: Ataluren study 030 was an observational, open-label Phase 2 study designed to evaluate the safety and pharmacokinetics (PK) of ataluren (10, 10, and 20 mg/kg) in patients aged ≥2 to <5 years with nmDMD. The study included a 4-week treatment period, a 48-week extension period, and a 4-week follow-up period. Secondary objectives in Study 030 evaluated changes in timed function tests (TFTs) and the 3-part and 8-part North Star Ambulatory Assessment (NSAA) scales, adapted for children <5 years of age. All patients were male (N=14) with genotypic confirmation of nmDMD. Results: Two patients were excluded from the current analysis: one patient did not have reported functional assessment at Week 28; and one patient did not have baseline measurement all for post line evaluations, resulting in N=12. Seven out of the fourteen patients in the safety population (50%) reported ≥1 treatment-emergent adverse event (TEAE) during the extension phase, all of which were deemed unrelated to the study drug; there were no serious TEAEs or discontinuations due to a TEAE. Pyrexia, ear infection, and nasopharyngitis were the most common TEAEs, each occurring in 2 patients (14.3%). The interim analysis presented (Table) represents a preliminary assessment of ataluren’s efficacy after 28 weeks of treatment. Conclusion: These interim data represent preliminary assessments of ataluren’s safety and efficacy after 28 weeks of treatment in patients with nmDMD aged ≥ 2 to < 5 years.

PS1Group1-127 / #456A FEMALE CARRIER OF BECKER MUSCULAR DYSTROPHY PRESENTING WITH A MYOPATHY WITH PIPESTEM CAPILLARIES

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Giuseppe Cosentino¹, Filippo Brighina², Brigida Fierro², Laura Pilati², Massimiliano Mirabella³, Carmelo Rodolico⁴

¹University of Palermo, Palermo, IT;²University of Palermo, Palermo, IT;³Cattolica University, Roma, IT;⁴University of Messina, Messina, IT

Background: Myopathy with pipestem capillaries represents a very rare entity of uncertain classification with a poor prognosis, characterized by necrosis of muscle fibers, minimal cellular infiltration, and vessel wall thickening with luminal narrowing. Methods: We describe the case of a carrier woman of Becker muscular dystrophy (BMD), who presented at the age of 61 yr with acute onset of neck and shoulder pain followed by proximal weakness of the upper limbs and the neck. Over the next 4 years, weakness progressively worsened also involving the distal muscles of the upper limbs and the pelvic girdle muscles. The electromyographic evaluation showed myopathic signs with minimal denervation in the affected muscles. Serum levels of creatine kinase were slightly increased, and a myositis-specific antibody panel was negative. A muscle biopsy of the right tibialis anterior muscle showed abnormal variation in fiber size with thin atrophic fibers, central nuclei, presence of numerous pipestem capillaries, and minimal necrosis of muscular fibers. Some cytochrome-oxidase (COX) negative muscle fibers compatible with slight mitochondrial abnormalities were also observed. As autoimmunity is considered to play a role in the development of myopathy with pipestem capillaries, patient was treated with oral corticosteroids, which determined a slight improvement (especially as regards pain). Patient also underwent a trial with azathioprine, that was stopped after several months due to inefficacy, and subsequently a trial with methotrexate, which was also soon discontinued due to side effects. At the moment the patient refuses any immunosuppressive therapy except for prednisone, and its clinical status is quite stable. Results: This case suggests that, albeit rarely, a necrotizing myopathy with pipestem capillaries could occur in previously asymptomatic patients with dystrophin gene mutations. Conclusion: The present case has having a more favorable outcome than previously reported in the literature. The role of dystrophinopathy as a triggering factor for this rare form of myopathy and/or as a disease modifier could be hypothesized though it remains questionable.

PS1Group1-128 / #459URINARY TITIN IS A NON-INVASIVE BIOMARKER TO DIAGNOSE DUCHENNE MUSCULAR DYSTROPHY EVEN IN ADVANCED STAGE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Hiroyuki Awano¹, Yuka Ishikawa², Yukitoshi Ishikawa², Masaaki Matsumoto³, Masashi Nagai³, Taku Shirakawa⁴, Nobuhiro Maruyama⁵, Yo-Ichi Nabeshima⁶, Kazumoto Iijima³, Masafumi Matsuo⁴

¹Pediatrics, Kobe University Graduate School of Medicine, Kobe, JP;²Yakumo National Organization Hospital, Yakumo, JP;³Pediatrics, Kobe University Graduate School of Medicine, Kobe, JP;⁴Physical Therapy, Kobe Gakuin University, Kobe, JP;⁵Immuno-Biological Laboratories Co., Ltd., Fujioka, JP;⁶Laboratory Of Molecular Life Science, Foundation for Biomedical Research and Innovation, Kobe, JP

Background: Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disease caused by lack of dystrophin. As the disease progresses, muscle mass decreases. Loss of muscle mass is supposed to reduce leaking enzymes including creatine kinase (CK), a most common-used biomarker for DMD. Therefore, reliable biomarker regardless of muscle loss is required to evaluate the status of dystrophic muscles, especially in advanced stage of DMD patients Titin/connectin is the largest protein in human and functions as molecular spring in the sarcomere. We previously reported titin-fragment in urine was a novel disease progression biomarker correlated with serum CK in young DMD patients (Awano et al. 2017). Urinary titin in advanced DMD remains unknown. In this study, we measured urinary titin level of advanced DMD patients and examined the association between urinary titin and serum CK. Methods: Sixty-two DMD patients from aged 21 to 50 years and 15 healthy male controls were enrolled in this study. Titin was quantified using Titin N-Fragment Assay Kit – IBL (Immuno-Biological Laboratories Co, Ltd., Fujioka, Japan). Titin was normalized to urine creatinine concentration and was expressed as pmol/mg creatinine (Cr). Statistical analysis was analyzed by Mann-Whitney U test, ANOVA, and logistic regression analysis. Receiver operating characteristic (ROC) curve was generated and area under the curve (AUC) was calculated by GraphPad PRISM 7.02 (Graphpad Software, CA, USA). Values of p <0.05 were concidered statistically significant. The protocol of this study was approved by the ethical committee. Results: Urinary titin was determined in 62 and 15 samples in advanced DMD patients and controls, respectively. In advanced DMD patients, median concentration of urinary titin was 57.7 pmol/mg Cr. This was significantly higher than those of controls (1.8 pmol/mg Cr) (p<0.0001). The AUC in the ROC curve was 0.99, indicating that urinary titin was a diagnostic biomarker in progressed stage of DMD. We previously reported that urinary titin decreased by aging and was significantly correlated to serum CK concentration in DMD patients (Awano et al.2017). An association between concentration of urinary titin, and age or serum CK was investigated by liner regression analysis. The analysis revealed that urinary titin showed a significant decline with age (p<0.0001) and a positive correlation to serum CK (p<0.001). It was noted that 46 out of 62 patients (74.2%) had normal or low CK level. On the other hand, all except 1 patients showed higher titin concentration than controls. Conclusion: Urinary titin was first disclosed to be higher than healthy males in advanced DMD patients and demonstrated to be an accurate biomarker for DMD diagnosis even in elder patients. Notably, urinary titin was elevated in DMD patients who had normal or low CK level. This suggested that titin fragmentation was still active in the progressed-stage patients. It was indicated that urinary titin was a better biomarker than serum CK in advanced DMD patients. Reference; Awano H, et al. Diagnostic and clinical significance of the titin fragment in urine of Duchenne muscular dystrophy patients. Clin Chim Acta. 476.111-116.2018

PS1Group1-129 / #830A NOVEL MUSCLE PHENOTYPE IN A PATIENT WITH TROPOMYOSIN-RECEPTOR KINASE-FUSED GENE (TFG) DISEASE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Nicolas N. Madigan¹, Jennifer A. Tracy¹, William J. Litchy¹, Zhiyv Niu², Margherita Milone¹

¹Neurology, Mayo Clinic, Rochester, MN, US;²Laboratory Genetics & Genomics, Mayo Clinic, Rochester, MN, US

Background: The tropomyosin-receptor kinase-fused gene (TFG) protein is ubiquitously expressed across tissues, including muscle, and is predominantly present in neural tissue. Autosomal dominant TFG mutations were first identified in Okinawa and Kansai prefecture patients with proximal weakness and distal sensory loss, who were diagnosed with a hereditary sensorimotor neuropathy (HSMNO). Pathological studies later demonstrated that HSMNO is a motor neuronopathy with associated sensory ganglionopathy. Limited muscle pathological findings showing fiber size variability and fiber type grouping have been reported. TFG-related neurological disorders are now understood to encompass a spectrum of phenotypes which include Charcot-Marie-Tooth disease type 2 (CMT2) and hereditary spastic paraplegia. Recently there have been several other genes that are recognized to cause motor neuron disease, neuropathy and myopathy. Methods: Review of clinical and laboratory data in a patient with TFG-related neurological disease. Results: A 44-year-old Caucasian male presented with a 7 year history of upper and lower limb muscle fasciculation and cramps, progressive asymmetric proximal more than distal weakness, muscle atrophy and length-dependent sensory loss. He was areflexic. He had bilateral pes cavus. He could not walk on either his toes or heels. Serial measurements of serum creatine kinase ranged between 1897-2400 U/L (normal <336). Neurophysiologic studies demonstrated findings suggestive of a diffuse disorder of motor neurons in association with a sensory neuronpathy. Muscle biopsy of the quadriceps showed fiber type grouping and atrophic fibers of either histochemical type, but also several fibers with rimmed and non-rimmed vacuoles, increased numbers of internalized nuclei, fiber splitting, and necrotic and regenerating fibers. In addition there were several foci of perivascular inflammatory cells. Next generation exome sequencing detected a known pathogenic heterozygous missense variant in exon 8 (c.854C>T, p.Pro285Leu) of theTFG gene, affecting the carboxy-terminal proline-glutamine rich (P/Q) protein domain. Conclusion: Our patient presented with a classic clinical phenotype of HSMNO and a known pathological genotype. Prominent rimmed and unrimmed vacuoles were present in several muscle fibers, which suggests an associated myopathic component separate from neurogenic changes. Of interest, the function of the TFG protein relates to vesicle trafficking of unfolded and misfolded proteins through the endoplasmic reticulum and the ubiquitin-proteasome system (UPS). The P/Q domain specifically regulates the interaction with the UPS, and disruption of this domain may lead to accumulation of abnormal protein in motor neurons as well as in muscle.

PS1Group1-130 / #264GLYCOGEN STORAGE DISEASE TYPE IV PRESENTING AS CONGENITAL MYOPATHY WITH CONTRACTURES AND RIGID SPINE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Maggie C. Walter¹, Stephan Wenninger¹, Angela Abicht²

¹Dept. Of Neurology, Ludwig-maximilians-university, Friedrich-Baur-Institute, Munich, DE;²Medical Genetic Center, Munich, DE

Background: Glycogen storage disase type 4 (GSD4) ist an autosomal recessive disorder caused by branching enzyme deficiency. The phenotype is very heterogeneous, ranging from a congenital or infantile neuromuscular disorder to late-onset polyglycosan body disease. We report on a 5-year-old girl from Ukraine, presenting with elongated facial bones, proximal weakness, atrophy of the shoulder girdle muscles, severe hip, knee and ankle contractures, hyperlaxity of elbow joints and rigid spine. First symtoms were noted at birth in form of hypotonia and congenital arthrogryposis with bilateral hip luxation, requiring splint treatment for six months. Motor milestones were mildly delayed, turning around at 5 months of age, sitting at 7 months, crawling at 2,5 years, standing on knees from age 3; however, walking was never achieved. The parents are non-consanguineous, the patient is the only child, there are no other affected family members. Methods: We perfomed a clinical and electrophysiological examination, timed function test, oximetry, lung function test, cranial MRI, cardiac and abdominal ultrasound, along with a blood test for CK and multigene panel diagnostics for congenital myopathies. Results: Clinical testing revealed normal cranial nerves, no facial weakness, no high palate, but elongated facial bones, no macroglossia, atrophy of shoulder girdle muscles and proximal paresis of arm and leg muscles. The arms could be elevated up to 45°. Severe contractures in hips, knees and ankles along with pes equinus was detected, while elbow, hand and finger joints showed hyperlaxity. Manual muscle strength showed bilaterally MRC 3/5 in arm elevation, biceps brachiii 4+/5, triceps 4+/5. Head flexor and extensor 4-/5, quadriceps right 4-/5, left 3+/5, iliopsoas 5-/5 and gluteus 4+/5 bilaterally. Hand grip dynamometry revealed 2 kg bilaterally. The patient can sit independently, and gets up from lying position with the help of the arms. Independent standing or walking is not possible. Bilateral scapular winging, hyperlordosis, and rigid spine, but no scoliosis or stiff neck was seen. Tiimed test 6.43 sec. from lying to sitting position, displaying beevor’s sign. Coordination and sensibility was intact, nerve conduction velocities were normal. Electromyography in proximal and distal leg muscles showed mild myopathic changes if any, CK levels were normal. Cranial MRI, cardiac and abdominal ultrasound showed normal results. Puls oximetry was normal, while vital capacity was reduced with 0.57l and 66% of normal in sitting, and 58% of normal in lying position. However, the little patients cooperation was compromised by the language barrier. At age 5, height was 115 cm, weight 15 kg. Multigene panel diagnostics for congential myopathies, including collagen-6 deficiency, which we had initially suspected, did not reveal any pathogenic mutations. Therefore, we broadened the panel and detected two mutations in the GBE1 gene: c.691+2T>C and c.708G>C, both previously described as pathogenic in GSD4. Segregation analysis in the parents was in line with the autosomal recessive trait. Conclusion: Our studies provide new insights in the heterogeneity of genotype/phenotype correlations in glycogen storage diseases and congenital myopathies. Even though GSD4 represents a rare condition, testing should be included into the diagnostic work-up of congenital myopathies with contractures, rigid spine and/or joint hyperlaxity.

PS1Group1-131 / #475STATIN-ASSOCIATED AUTOIMMUNE NECROTIZING MYOPATHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

So Hyun Ahn¹, Jung-Joon Sung², Yoon-Ho Hong³, Kyoung Hyun Kwun¹, Jin Ah Kim¹, Je-Young Shin⁴, Sung Min Kim¹, Ah Won Kim¹

¹Neurology, Seoul National University Hospital, Seoul, KR;²Neurology, Seoul National University College of medicine, Seoul University Hospital, Seoul, KR;³Seoul National University College of medicine, SMG-SNU Boramae Medical Center, Seoul, KR;⁴Seoul National University Hospital, Seoul, KR

Background: Necrotizing autoimmune myopathy presents with subacute proximal limb muscle weakness and a high serum creatine kinase (CK) level. Statins are generally well tolerated, but recently, progressive necrotizing myopathy leading to profound weakness has been directly linked to statin therapy. Methods: Case1 : A 63-year-old woman presented to our hospital with progressive weakness on both upper and lower extremities. She had a history of taking statin medication 10 months ago. Needle electromyography demonstrated features consistent with an active myopathy. Her serum CK level was 13237 IU/L. She treated with IV steroid pulse therapy suspected as r/o dermatomyositis or polymyositis. After then, initially she showed responsiveness of steroid therapy, but her symptom was exacerbated while steroid tapering. At January 2016, She presented dysphagia and newly appeared both arm weakness. Muscle biopsy showed some necrotizing and regenerating myofibers without infiltration of inflammatory cells in endomysium or perivascular area. She treated with oral steroid and immunosuppressive agents, and her symptoms was improved and serum CK level was also decreased.

Results: Case 2: A 65-year-old woman presented to the neurology department with progressive weakness on both legs. She took stains for two years for preventing atherosclerosis. The weakness of both legs worsened and she could not climb the stairs and could not walk without assistance. Serum CK level was 1994 IU/L. Muscle biopsy showed some necrotizing and regenerating myofibers without infiltration of inflammatory cells in endomysium or perivascular area. She treated with IV methylprednisolone, and followed by oral prednisolone and tacrolimus.

Conclusion: We reported two cases of statin-associated autoimmune necrotizing myopathy. The distinct histologic profile consists of profound necrotic, degenerating, or regenerating muscle fibers without inflammation. It may occur anytime and even long after initial exposure or statin cessation. Proper awareness of this rare complication is important to prevent further damage from statin use and treatment plan.

PS1Group1-132 / #881PHENOTYPIC HETEROGENEITY IN THREE PATIENTS WITH M.3243A>G MUTATION

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Birute Burnyte¹, Kristina Grigalioniene¹, Arunas Vaitkevicius², Donatas Petroska³, Loreta Cimbalistiene¹, Vaidutis Kucinskas¹, Algirdas Utkus¹

¹Institute Of Biomedical Sciences Of The Faculty Of Medicine, Vilnius University, Vilnius, LT;²Institute Of Clinical Medicine Of The Faculty Of Medicine, Vilnius University, Vilnius, LT;³Department Of Pathology, Forensic Medicine and Pharmacology of the Faculty of Medicine of Vilnius University, Vilnius, LT

Background: Mitochondrial myopathy, encephalopathy, lactic acidosis and stroke-like episodes (MELAS) syndrome is the most frequent syndromic manifestation of the m.3243A>G mutation. We aim to describe the phenotypic variability of three adult patients harboring the m.3243A>G mutation. Methods: Patients were identified in the research project during years 2015-2017. All three unrelated adult patients underwent extended clinical, laboratory, imaging and neurophysiological evaluations. An open muscle biopsy was performed in two patients for diagnostic purposes prior to the molecular study. Mitochondrial DNA (mtDNA) was investigated to determine disease mechanisms. The whole-length Sanger sequencing for detection of pathogenic point variants and long PCR and Multiplex Ligation-dependent Probe Amplification (MLPA) methods for detection of mtDNA deletions/duplications were applied. Results: We identified three female patients with the m.3243A>G mutation. The average age at onset was 21.3 and at diagnosis 40.3 years. All three patients had short stature, ptosis, hearing impairment, dysarthria, dysphonia, feeding difficulties, exercise intolerance and muscle weakness as well gastrointestinal dysmotility, diarrhoea, constipation and abdominal distension. One patient manifested with ataxic syndrome, one with acute severe weakness after exposure to chemical agents at work, and one with slowly progressive exercise intolerance. Pigmentary retinopathy was detected in one patient. Liver impairment was observed in one patient, and liver biopsy showed macrovesicular steatosis. Only one patient showed persistent mild lactic acidosis. Endocrine dysfunction was observed in two patients, and was represented by diabetes mellitus type I and hypogonadism, and diabetes type II, respectively. Cardiac involvement was detected in one patient. Respiratory involvement was not observed in all three patients. No one referred a migraine. Sudden neurological deterioration was observed in two patients. Electroneurography in two patients showed decreased axonal amplitudes of sensory nerves. Electromyography was myopathic in two patients. Muscle biopsies were performed in two patients and showed ragged red fibers and COX deficiency until 10% of myocites only in one patient’s biopsy (from m. guadriceps femori). Neuroimaging showed diffuse cerebral and cerebellar atrophy in one patient, and subcortical focal abnormalities in two patients. EEG abnormalities were not observed in all patients. One patient presented lack of social interactions and emotional instability. Pathogenic variant m.3243A>G was detected in all the patients and heteroplasmy levels were less than 50% for pathogenic variant. Large-scale mtDNA deletions or duplications were not detected in all three cases. Conclusion: We report detailed phenotypic and genetic characteristics of three unrelated Lithuanian patients with the m.3243A>G mutation. Although the patients harbor the same mutation, they demonstrate a heterogeneous phenotype. Since the heteroplasmy level is not the main consideration explaining the phenotypic variability, our study supports the previous research findings that nuclear genomic factors also contribute to the phenotypic expression of MELAS. Supported by grant TAP LLT-02/2015.

PS1Group1-133 / #485DOUBLE TROUBLE: A CHILD WITH DUCHENNE MUSCULAR DYSTROPHY AND NOONAN SYNDROME

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Yun Jeong Lee¹, Heamin Jang², Ji Young Park³, Jin Sung Park⁴

¹Pediatrics, School of Medicine, Kyungpook National University, Daegu, KR;²Pediatrics, Kyungpook national university children’s hospital, Daegu, KR;³Pathology, School of Medicine, Kyungpook National University, Daegu, KR;⁴Neurology, School of Medicine, Kyungpook National University, Daegu, KR

Background: Duchenne muscular dystrophy (DMD) is an X-linked disorder, caused by mutation in the DMD gene, which encodes the dystrophin protein and affects 1 in 3600-6000 live male births. Noonan syndrome (NS) is a multiple congenital anomaly syndrome with a prevalence of 1:1000. It is clinically characterized by facial dysmorphism, growth retardation and congenital heart defects. In addition skeletal, genitourinary and skin manifestations can be also observed. Recent literatures show that approximately 50% of NS is caused by heterozygous missense mutations in PTPN11 gene. Herein, we describe a rare case of a child with coinheritance of DMD and NS based on pathology study and genetic analysis using the next generation sequencing. Methods: 8 year-old boy was referred to our hospital due to elevated serum creatine kinase level (CK level; 8250 U/L) and progressive proximal limb weakness. He had a past history of pulmonary stenosis and aterial septal defect diagnosed at 1 year of age. The neuropsychological test reflected language, and cognitive developmental delay compared to his age. The patient showed waddling gait, Gower sign and calf muscle hypertrophy. The morphology of the patient was typical of NS, including short stature and dysmorphic facial features such as webbed neck, low posterior hair line, triangle shaped face, small chin, wild forehead, prominent nasolabial fold, low set posteriorly rotated ear and down slanting palpebral fissures. The needle electromyography study showed short amplitude, polyphasic motor unit potentials that were compatible with a myopathy. However clinical feature of proximal limb weakness and hyperCKemia are not common features of NS. Results: Therefore, we proceeded with the muscle biopsy that showed severe dystrophic alterations with marked size variation and perimysial fibrosis in the Hematoxylin-Eosin stain and complete loss of dystrophin was observed in dystrophin staining, that were consistent with dystrophinopathies. DNA analysis by multiplex ligation-dependant probe amplification (MLPA) analysis of the DMD gene was negative. Therefore, next generation sequencing (NGS) analysis was utilized and hemizygous c.3433-13T>A in DMD gene was found and this was predicted to disrupt the highly conserved acceptor splice site of exon 26. In addition, a known pathogenic heterozygous missense mutation in c.236A>G in PTPN11 gene was also detected. With the above clinical, pathologic features and genetic results, the patient was diagnosed to have a double trouble of DMD and NS. Conclusion: There are reports on double trouble of two different monogenetic diseases. Previous studies have described coexistence of NS with 22q11.2 deletion syndrome, retinitis pigmentosa, neurofibromatosis and Charcort-marie-tooth disease. A recent report described a double trouble found in Becker muscular dystrophy and NS via muscle biopsy and genetic testing in accordance to our study. Our study is of significance as this is the first report of double trouble of DMD and NS and currently we have proceeded with the functional study to verify the pathogenicity of our novel mutation.

PS1Group1-134 / #926THE HETEROZYGOUS R155C VCP MUTATION: TOXIC IN HUMANS, HARMLESS IN MICE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Christoph Clemen¹, Lilli Winter², Karl-Heinz Strucksberg³, Carolin Berwanger¹, Matthias Türk⁴, Ludwig Eichinger³, - The German Mouse Clinic Consortium⁵, Rolf Schröder⁶

¹Department Of Neurology, Heimer Institute For Muscle Research, Ruhr-University Bochum, Bochum, DE;²Center For Anatomy And Cell Biology, Medical University of Vienna, Vienna, AT;³Institute Of Biochemistry, Medical Faculty, University of Cologne, Cologne, DE;⁴Department Of Neurology, Friedrich-Alexander University Erlangen-Nürnberg (FAU), Erlangen, DE;⁵The German Mouse Clinic, Munich, DE;⁶Neuropathology, University Hospital Erlangen, Erlangen, DE

Background: VCP, a very abundant and evolutionarily highly conserved member of the Triple-A ATPase family, is involved in a plethora of cellular processes such as membrane dynamics, protein quality control, cell cycle, apoptosis, and DNA damage response. Mutations in the VCP gene cause Inclusion Body Myopathy associated with Paget disease of bone and Fronto-temporal Dementia (IBMPFD). Moreover, four more neurodegenerative disorders, Amyotropic Lateral Sclerosis (ALS), Parkinson’s disease, Hereditary Spastic Paraplegia, and Charcot-Marie-Tooth disease type 2 (HMSN2) have been attributed to VCP missense mutations. The exact molecular mechanisms by which VCP mutations cause these late-onset disorders remain elusive. In the present study, we report on the generation and comprehensive analysis of a R155C VCP knock-in mouse model, which harbors the ortholog of one of the most frequently occurring human pathogenic VCP mutations. Methods: i) generation of R155C VCP knock-in mice; ii) comprehensive phenotypic and morphological analyses at the German Mouse Clinic Consortium in Munich; iii) VCP mRNA and protein expression analyses; iv) comparative myopathological analysis of human and murine R155C VCP mutant skeletal muscle tissue. Results: We successfully generated a R155C VCP knock-in mouse strain (B6J.B6J-Vcp^{tm2(R155C)Ccrs}) using an appropriate targeting vector for homologous recombination. To restore the original VCP gene structure, mice were bred to C57BL/6J mice expressing Cre recombinase for removal of the neomycin selection cassette. Correct gene targeting was confirmed by Southern blotting, PCR genotyping, and sequencing of both genomic and complementary DNA. Breeding of heterozygous R155C VCP knock-in mice did not yield in the generation of mice homozygous for the R155C VCP mutation. VCP immunoblotting indicated unchanged VCP protein levels in skeletal muscle and brain tissue derived from heterozygous mice as compared to wild-type littermates. Notably, our comprehensive phenotypic and morphological analyses of heterozygous R155C VCP knock-in mice did not reveal any signs of a previously described mutant VCP-related striated muscle, bone or central nervous system pathology. In comparison to wild-type littermates, heterozygous mice showed aberrant parameters for plasma lactate, fasting cholesterol, serum albumin, oxygen consumption, platelets, CD8+/Ly6C+ T-cells, and liver weight. The pathological significance of these findings is currently unclear. Conclusion: While the heterozygous R155C VCP mutation has been shown in several reports to cause IBMPFD and ALS in humans, our analysis of corresponding R155C VCP knock-in mice did not detect any signs of a striated muscle, bone or central nervous system pathology. Though the failure to generate mice homozygous for the R155C VCP missense mutation clearly denotes a toxic effect not compatible with life, the lack of any clear-cut VCP-related pathology in heterozygous R155C knock-in mice is somewhat unexpected and may be attributed to an R155C VCP expression level below a disease-causing threshold. This issue is currently addressed in further experiments.

PS1Group1-135 / #497ADAPTIVE PROTEIN QUALITY CONTROL RESPONSE IN DESMINOPATHY SKELETAL MUSCLE CELLS AND TISSUE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Christoph Clemen¹, Lilli Winter², Carolin Berwanger³, Marina Spörrer⁴, Ursula Schlötzer-Schrehardt⁵, Rolf Schröder⁶

¹Department Of Neurology, Heimer Institute For Muscle Research, Ruhr-University Bochum, Bochum, DE;²Center For Anatomy And Cell Biology, Medical University of Vienna, Vienna, AT;³Department Of Neurology, Heimer Institute For Muscle Research, Ruhr-University Bochum, Bochum, DE;⁴Department Of Physics, Friedrich-Alexander-University Erlangen-Nuremberg, Erlangen, DE;⁵Department Of Opthalmology, University Hospital Erlangen, Erlangen, DE;⁶Neuropathology, University Hospital Erlangen, Erlangen, DE

Background: Mutations of the human desmin gene on chromosome 2q35 cause autosomal-dominant and -recessive myopathies and cardiomyopathies with marked clinical variability. For pathophysiological and therapeutic studies, we generated and characterized hetero- and homozygous R349P desmin knock-in mice, which serve as patient-mimicking disease models for dominant and recessive desminopathies with maintained protein expression. By crossbreeding our desminopathy mouse strain with p53 knock-out mice, we now generated immortalized desminopathy myoblast cell lines. We used these immortalized desminopathy myoblasts in conjunction with skeletal muscle tissue from the corresponding desminopathy mice to study the effects of R349P mutant desmin on the ubiquitin-proteasome system, bulk autophagy, chaperone-assisted selective autophagy, and heat shock proteins. Methods: i) R349P desmin knock-in mice; ii) p53 knock-out mice; iii) immortalized R349P desmin knock-in skeletal muscle myoblasts and myotubes; iv) indirect immunofluorescence microscopy; v) determination of proteasomal activity; vi) immunoblotting addressing autophagy rate, chaperone-assisted selective autophagy (CASA), and heat shock protein levels. Results: We crossbred our R349P desmin knock-in mouse line with p53 knock-out mice, prepared muscles from offspring with the following genotypes, hom R349P desmin knock-in/hom p53 knock-out, het R349P desmin knock-in/hom p53 knock-out, and wild-type littermates/hom p53 knock-out, and finally generated immortalized satellite cell-derived myoblast cultures. Desmin immunoblots and immunostains of differentiated myotubes revealed that these desminopathy cell models closely mirror central aspects of the desmin pathology observed in our desminopathy mice. Proteasomal activity measurements in muscle tissue lysates revealed a 1.23-fold and a 1.47-fold increase in hetero- and homozygous R349P desmin knock-in mice, respectively, as compared to the wild-type. Notably, treatment of the desminopathy myotubes with the proteasome inhibitor MG132 did not alter the levels of both wild-type and R349P mutant desmin protein. Immunoblotting of tissue and myotube lysates demonstrated markedly increased levels of the serin/threonin protein kinase Ulk-1 and sequestosome 1 (p62/SQSTM1) as well as of p62/SQSTM1 and LC3-II, which are classical autophagy-related markers. Furthermore, we detected increased protein levels of filamin-C and BAG-3, which are essential components of the CASA system. Finally, we assessed the protein levels of aB-crystallin, Hsp27, and Hsp90, and found increased signal intensities in skeletal muscle homogenates from homozygous mice, while only aB-crystallin and Hsp27, but not Hsp90, were increased in both desminopathy myotube genotypes. Conclusion: Our analyses in the newly generated immortalized desminopathy muscle cell cultures in conjunction with their corresponding desminopathy mouse models revealed a complex pattern of adaptive protein quality control response to the presence of R349P mutant desmin. Key findings are the upregulation of proteasomal activity, autophagy, CASA, and heat shock protein levels, which were predominantly seen in the homozygous and, to a lesser extent, in the heterozygous R349P desmin knock-in skeletal muscle tissues and cultured immortalized muscle cells.

PS1Group1-136 / #514CLINICAL BACKGROUND OF 94 ADULT PATIENTS WHO RECOGNIZED NEMALIN RODS IN MUSCLE TISSUE

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Akihiro Hashiguchi¹, Kento Kodama², Itsuro Higuchi³, Hiroshi Takashima⁴

¹Neurology, Neurological Disease Center, Kagoshima University Hospital , Kagoshima city, JP;²Department Of Neurology And Geriatrrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, JP;³Physical Therapy Foundation Course, Kagoshima University School of Health, Kagoshima, JP;⁴Department Of Neurology And Geriatrrics, Kagoshima University Graduate School of Medical and Dental Sciences, Kagoshima, JP

Background: It is natural to recognize nemaline rods in muscle tissue in congenital nemaline myopathy patients. On the other hand, we sometimes find unexpected nemaline rods in adult muscle tissue. From the muscle biopsy record of the past 40 years, we will clarify the background of adult patients with nemaline rods. Methods: We extracted adult cases with nemaline rods from the muscular pathological reports analyzed in our facility over the past 40 years. We compared the clinical background and pathology of cases. Results: We extracted 94 adult cases with nemaline rods. In the pathological classification of 94 cases, myopathy was 72 cases, neuropathy was 16 cases, and merger of both was 6 cases. The age at examination was widely distributed in the 20s to 80s, and no characteristic was seen by age. In myopathy 72 cases, inflammatory myopathy was included in 13 cases (18%).Eight cases of 16 cases of neuropathy were motor neuron disease such as amyotrophic lateral sclerosis, hereditary motor neuropathy, Kugelberg-Welander disease. Many cases coexisting with changes of mitochondrial abnormality, rimmed vacuole and cores. Conclusion: There is no disease specificity in the adult neemarin rod, not only in various myopathies but also in neuropathy.

PS1Group1-137 / #720P62 IMMUNOSTAINING COULD HELP IN DIFFERENTIATING POLYMYOSITIS FROM SIBM

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

José C. Milisneda¹, Cristina Jou², Iago Pinal-Feranndez³, Josep M. Grau⁴

¹Internal Medicine, Hospital Clínic de Barcelona, Barcelona, ES;²Hospital Sant Joan de Déu, Barcelona, ES;³National Institute Of Arthritis And Musculoskeletal And Skin Diseases, National Institutes of Health, Bethesda, Maryland, AL, US;⁴Internal Medicine Service, Hospital Clínic de Barcelona, Barcelona, ES

Background: The sensitivity and specificity of the existing criteria for sIBM have been reviewed recently, with high specificity but variable sensitivity. In consequence major problems arise for the diagnosis in early stages or to predict when a polymyositis is going to become a sIBM. Our objective was to investigate the utility of p62 immunostaining to predict when a PM is going to become a sIBM. Methods: This retrospective study enrolled a sample from the longitudinal muscle unit cohort of Hospital Clínic de Barcelona. We compared 4 muscle biopsies from (clinico-pathologically well-defined sIBM), with seven patients classified as having PM, based on European Neuromuscular Center (ENMC) criteria, and with normal muscle biopsies (control group). The PM cases were divided in two groups, because four of them had an associated disease (autoimmune or cancer) and the rest had an isolated PM. Clinical data was review from clinical charts, and p62 histopathological analysis was made with double immunofluorescence. In addition the amount of p62 in muscle biopsies was quantified using “Image J” software. Results: We observed a significant increase of p62 expression (expressed in % of muscle area) in the isolated PM group, compared with the other PM cases (associated to a SLE, systemic sclerosis, HLAB27+ artrhopathy, and non-Hogkin lymphoma) and normal group. Also the expression of p62 was higher in the sIBM group. Of note was the poor response to immunesuppresive therapy in the four isolated PM cases, and furthermore one of them developing a typical clinical phenotype of sIBM, confirmed by a second muscle biopsy six years later. Picture. Double immunofluorescence for p62. A) Normal patient. B) PM with associated disease. C) Isolated PM. D) sIBM. Conclusion: Despite the limitations of the present study, it seems that p62 positivity immunostaining could help in the identification of refractory isolated PM cases, with high probability to evolve to classical sIBM.

PS1Group1-138 / #347HOMOZYGOSITY OF THE AUTOSOMAL DOMINANT VCP P.ARG159HIS MUTATION

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Willem De Ridder¹, Tine Deconinck², Peter De Jonghe², Katherine Johnson³, Ana Töpf³, Marta Bertoli³, Lauren Phillips³, Daniel Macarthur⁴, Jonathan Baets²

¹Neurogenetics Group, Vib-uantwerp Center For Molecular Neurology, University of Antwerp, Antwerp, BE;²Neurogenetics Group, Vib-uantwerp Center For Molecular Neurology, University of Antwerp, Antwerp, BE;³John Walton Muscular Dystrophy Research Center, Newcastle University, Newcastle upon Tyne, GB;⁴Broad Institute of Harvard and MIT, Cambridge, MA, US

Background: Mutations in valosin containing protein (VCP) are linked to a dominantly inherited multisystem proteinopathy (MSP1) with inclusion body myopathy (IBM), Paget disease of bone (PDB) and frontotemporal dementia (FTD). Additional phenotypes have been described recently. More than 40 different missense mutations have been reported to date. Many gaps remain in our knowledge of this intriguing disorder with regard to molecular mechanisms of the disorder, genotype-phenotype correlations and penetrance. Methods: We studied a family in which the currently 33-year-old male index patient and his father exhibited progressive limb-girdle weakness. Whole-body muscle magnetic resonance imaging (MRI) was performed on a 1.5T MRI platform. Muscle biopsies were obtained from quadriceps muscle and analysed following standard histologic and immunohistochemical techniques for light microscopy. Whole exome sequencing of leucocyte DNA of the index patient was performed. Genes known to be associated with limb-girdle weakness, including VCP, were analysed for pathogenic variants. A candidate variant in VCP was confirmed by Sanger sequencing and segregation analysis was performed with available DNA-samples of family members. Results: We describe clinical, radiological and anatomopathological details for the index patient and his father. Intriguingly, on the maternal side of the family, many individuals had been diagnosed with a dementia phenotype in the past. To our surprise, the index patient was homozygous for the known p.Arg159His mutation in VCP. When studying the familial history in detail, we identified distant consanguinity between the parents of the index patient. Comprehensive baseline studies were performed to evaluate potential subclinical bone or central nervous system involvement. Conclusion: We identified the known VCP p.Arg159His mutation in homozygosity in a patient exhibiting a MSP1 phenotype. The phenotype of the index patient does not seem to be strikingly worse compared to heterozygous patients. Homozygous mutations in inherited autosomal dominant disorders are rare events. The case yields insightful and intriguing observations and incites to reflect on the presumably complex molecular mechanisms of VCP-linked disease.

PS1Group1-139 / #742GENOTYPE CHARACTERIZATION OF CZECH PATIENTS WITH FACIOSCAPULOHUMERAL DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Jana Zidkova¹, Stanislav Vohanka², Radim Mazanec³, Lenka Fajkusova⁴

¹Centre Of Molecular Biology And Gene Therapy, University Hospital Brno, Brno, CZ;²Neurology, University Hospital Brno, Brno, CZ;³Neurology, Second Faculty of Medicine, Charles University and University Hospital Motol, Prague, CZ;⁴University Hospital Brno and Masaryk University Brno, Brno, CZ

Background: Facioscapulohumeral dystrophy (FSHD) is an autosomal dominant muscle disorder characterized by progressive weakness of facial, scapular and humeral muscles. FSHD is commonly associated with contraction of the D4Z4 macrosatellite repeat on chromosome 4q35 (FSHD1) or with mutations in the SMCHD1 or DNMT3B gene (FSHD2). Both situations result in a partial opening of the D4Z4 chromatin structure and transcription of D4Z4-encoded DUX4 mRNA in muscles. A specific haplotype is necessary for stabilization of the DUX4 transcript by providing the polyadenylation signal and is called 4qA haplotype. Methods: The number of D4Z4 macrosatellite repeats was determined by pulsed-field gel electrophoresis, Southern blotting and hybridization with specific probes, and analysis of genes SMCHD1 and DNMT3B by gene panel sequencing. Results: The aim of our study was to confirm FSHD on molecular level. We tested FSHD1 in 400 patients and FSHD1 was confirmed in 210 of them. We correlated the available clinical data with detected number of repeats and found out that small number of repeats (1-3; 21% of probands) is connected with earlier onset and more severe phenotype. Most FSHD1 patients (69%) have medium number of repeats (4-8 repeats) and border number of repeats was detected only in 10% of probands. Conclusion: We detected two pathogenic variants in the SMCHD1 gene and so confirmed FSHD2. Both patients have 13 D4Z4 repeats and 4qA haplotype. This study was supported by the project of the Technology Agency of the Czech Republic (TE02000058) and the project of the Grant Agency of the Czech Republic (GA16-11619S/2016).

PS1Group1-140 / #362OCULOPHARYNGEAL MUSCLE WEAKNESS AFTER TREATMENT WITH CHECKPOINT INHIBITORS: PATHOLOGY IS BEYOND THE NEUROMUSCULAR JUNCTION

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Anahit C. Mehrabyan¹, Aiesha Ahmed², Charles Specht³

¹Neurology, University of North Carolina at Chapel Hill, Chapel Hill, US;²Neurology, PennState Hershey Medical Center, Hershey, PA, US;³PennState Hershey Medical Center, Hershey, PA, US

Background: Oculopharyngeal weakness related to checkpoint inhibitors became a well-known phenomenon over the last several years. The condition has been reported in patients with pre-existing myasthenia gravis, as well as de novo diagnosis after the initiation of treatment with checkpoint inhibitors. It has been reported after the use of programmed-death 1 (PD-1) and cytotoxic T-lymphocyte-associated protein 4 (CTLA-4) inhibitors, and combination of these agents. Methods: We report a case of progressive oculopharyngeal muscle weakness with detailed clinical follow up over the two months after the initial clinical presentation, laboratory, electrodiagnostic, immunologic and pathologic findings. Results: 69 yo man was diagnosed with recurrence of malignant melanoma with metastasis and was treated with combination of checkpoint inhibitors: Nivolumab (PD-1 inhibitor) and Ipilimumab (CTLA-4 inhibitor). He presented with an acute onset of right proximal leg weakness, which progressed to extraocular muscle weakness, asymmetric bilateral ptosis, pharyngeal, tongue and low facial muscle weakness, with subsequent resolution of right leg weakness and progression of oculopharyngeal symptoms. He was diagnosed with immune mediated myopathy based on clinical, laboratory, electrodiagnostic and histopathology findings. Conclusion: An isolated subacute acquired oculopharyngeal weakness in an adult population is the most common presentation of autoimmune mediated dysfunction of neuromuscular junction, myasthenia gravis. Here we present an unusual case of subacute onset of severe oculopharyngeal weakness due to autoimmune myopathy secondary to checkpoint inhibitors. Despite of unusual clinical presentation the cases of severe progressive muscle weakness with high suspicion for primary muscle pathology, including elevated creatine kinase (CK), negative/normal acetylcholine receptor antibodies, progression of symptoms despite immunotherapy, need thorough evaluation to exclude immune mediated myopathies, including detailed electrodiagnostic testing and muscle biopsy.

PS1Group1-141 / #755A CASE OF CENTRAL CORE DISEASE WITH NOVEL RYR1 MUTATION IN KOREAN PATIENT

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Je-Young Shin¹, Chanmi Huh², So Hyun Ahn³, Kyoung Hyun Kwun⁴, Jin Ah Kim⁴, Ah Won Kim⁴, Yoon-Ho Hong⁵, Jung-Joon Sung⁶

¹Neurology, Seoul National University Hospital, Seoul, KR;²Seoul National University Hospital, Seoul, KR;³Neurology, Seoul National University hospital , Seoul , KR;⁴Neurology, Seoul National University Hospital, Seoul, KR;⁵Seoul National University College of medicine, SMG-SNU Boramae Medical Center, Seoul, KR;⁶Neurology, Seoul National University College of medicine, Seoul University Hospital, Seoul, KR

Background: Central core disease (CCD), or central core myopathy, is a congenital myopathy with non-progressive muscle weakness, mainly inherited in an autosomal dominant pattern. The gene responsible for CCD is type I ryanodine receptor (RYR1). The C-terminal domain mutation of RYR1 is relatively well known for its genotype-phenotype correlation due to its typical clinical and pathologic features. Methods: In this case report, we present a Korean patient with de novo missense mutation of a C-terminal domain of RYR1 gene. The purpose of this study is to broaden genetic mutational spectrum and understanding of genetic-phenotype correlation in CCD. Results: A 31-year-old man presented with non-progressive bilateral gait disturbance which lasted for about fifteen years. The patient showed musculoskeletal problems. Serum creatinine phosphokinase level was normal. There was no specific finding in other laboratory tests including creatinine phosphokinase. Electromyography (EMG) findings showed myopathic patterns. The muscle biopsy revealed the typical histopathologic features of CCD. The sequence analysis showed de novo missense mutation [c.14815G>T (p.Asp4939Tyr)] of RYR1 gene in the proband. We found no genetic variant or mutation among other family members. Conclusion: We report one Korean patient with CCD in whom de novo missense mutation in the C-terminal transmembrane region of RYR1 gene was identified. This mutation is expected to be the ‘(likely) pathogenic variants.’ Although mutations in the C-terminal of RYR1 are known to have significant muscle weakness since neonatal period, the index case did not present muscle symptoms until his adolescent period. On the other hand, the patient exhibited non-progressive muscle symptoms with proximal weakness and musculoskeletal deformities; his histopathologic findings were consistent with typical CCD. In this sense, even though patients do not show clinical symptoms of typical CCD, we still need muscle biopsy and genetic analysis, especially when we cannot find other causes. We hope that this case report helps us to broaden our clinical spectrum of CCD in association with RYR1 gene mutation.

PS1Group1-142 / #999MYOADENILATE DEAMINASE DEFICIENCY IN PATIENTS WITH MYALGIA

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Gabriele Siciliano, Costanza Simoncini, Giulia Ricci

Department Of Clinical And Experimental Medicine, University of Pisa, Pisa, IT

Background: Myoadenylate deaminase deficit (MAD) is the most common cause of metabolic myopathies. Methods: In our Center, we routinely use forearm ischemic exercise testing for blood lactate and ammonium in evaluation of patients with exercise intolerance, myalgias, muscle cramps and/or hyperCKemia. Results: In the last 5 years, we have detected lack of increase in the blood ammoniun concentration during exercise in twelve unrelated patients, all affected by exercise intolerance with muscle cramps and myalgia. In these patients, genetic test confirmed the presence of mutations in AMPD1 gene, suggestive of myopathy due to myoadenylate deaminase deficiency (MAD). Conclusion: It has been reported that the spectrum of the MAD deficiency can range from asymptomatic carriers to patients who manifest exercise-induced muscle pain, fatigue, idiopathic hyperCKemia and, occasionally, rhabdomyolysis. MAD deficiency is not currently considered a well proven disease entity. Nevertheless, in people with muscle symptoms, AMPD1 gene mutations seem to be significantly more frequent than healthy population, suggesting a possible clinical significance of this defect.

PS1Group1-143 / #365A PHASE IIA STUDY OF TAS-205, A NOVEL INHIBITOR OF HEMATOPOIETIC PROSTAGLANDIN D SYNTHASE, IN DUCHENNE MUSCULAR DYSTROPHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Tsuyoshi Matsumura¹, Hirofumi Komaki², Satoshi Kuru³, Takahiro Nakayama⁴, Shinnichi Takeda⁵

¹Neurology, National Hospital Organization Toneyama National Hospital, Toyonaka, JP;²Child Neurology, National Center Hospital, National Center of Neurology and Psychiatry, Kodaira, JP;³Neurology, National Hospital Organization Suzuka National Hospital, Suzuka, JP;⁴Neurology, Yokohama Rosai Hospital, Yokohama, JP;⁵National Institute of Neuroscience, National Center of Neurology and Psychiatry, Kodaira, JP

Background: Inflammation has been included in the pathological process of Duchenne muscular dystrophy (DMD). Prostaglandin D₂ (PGD₂) is involved in inflammation, and hematopoietic PGD synthase (HPGDS) is expressed in myonecrotic areas in DMD. A phase I study demonstrated that TAS-205, a novel HPGDS inhibitor, was highly safe and tolerable in patients with DMD when given at 1.67 to 13.33 mg/kg as a single- and repeated- doses twice daily for 7 days. TAS-205 also decreased urinary excretion of tetranor-PGDM, the pharmacodynamics marker to show HPGDS inhibition. Based on the results of a phase I study, a phase IIa study was carried out. Methods: The primary objective of this double-blind randomized study was to evaluate the efficacy of TAS-205 orally administered twice daily for 24 weeks compared with placebo in ambulatory patients with DMD in an exploratory manner. The secondary objective was to evaluate the safety and dose response relationship in efficacy and safety, and also the effect on the urinary excretion of tetranor-PGDM. Subjects were randomized to one of 3 groups; low-dose group (6.67 to 13.33 mg/kg/dose), high-dose group (13.33 to 26.67 mg/kg/dose), and placebo group evenly. This study was carried out at 11 sites in Japan. Results: Thirty-six subjects were enrolled and 35 subjects were treated with the investigational product. The full analysis set consisted of 34 subjects, and the per protocol set consisted of 32 subjects where the main efficacy evaluation was conducted. The primary endpoint was the change from baseline in the measured 6-minute walk distance (6MWD) at week 24. It was -17.0 ± 55.6 m (mean value ± SD) in the placebo group, -3.5 ± 67.3 m in the low-dose group, and -7.5 ± 37.3 m in the high-dose group. The difference of the mean value from the placebo group was 13.5 m (p = 0.625) in the low-dose group and 9.5 m (p = 0.646) in the high-dose group. The decrease in 6MWD tended to be less in the TAS-205 groups as compared with the placebo group. The muscle volume index (%MVI) by skeletal muscle CT in the thigh and lower leg, as the secondary endpoint for efficacy, tended to be less decreased in the TAS-205 group as compared with the placebo group. Additionally, there were several subjects where muscle volume of the thigh and lower leg increased in high-dose group. The change rate in the urinary excretion of tetranor-PGDM corrected by creatinine from baseline significantly decreased in the high-dose groups as compared with the placebo group. No adverse drug reactions specific to the TAS-205 were observed, suggesting proper tolerability. Conclusion: From the above results, it was suggested that TAS-205 had a possibility of being effective for ambulatory patients with DMD.

PS1Group1-144 / #767USE OF HUMAN INDUCED PLURIPOTENT STEM CELLS FOR MODELLING SKELETAL MUSCULAR DEFECTS ASSOCIATED TO MYOTONIC DYSTROPHY TYPE 1

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Julie Tahraoui¹, Lea Lesueur², Christian Pinset³, Xavier Nissan², Denis Furling⁴, Cecile Martinat³

¹I-stem, Inserm Ueve Umr861, CORBEIL ESSONNES, FR;²I-stem, CECS, CORBEIL ESSONNES, FR;³I-stem, INSERM UEVE UMR861, CORBEIL ESSONNES, FR;⁴Institut De Myologie, Centre de Recherche en Myologie, UMRS974, PARIS, FR

Background: Myotonic Dystrophy type I (DM1) is a rare neuromuscular disease that is mainly characterized by myotonia, progressive muscle weakness and wasting. DM1 is an autosomal dominant disorder caused by an expanded CTG repeat in the 3’ UTR of DMPK gene with the size of the expanded repeats globally correlates with disease severity. This abnormal expansion leads to a toxic gain-of-function of the mutated mRNAs which aggregate within the nucleus in association with different RNA binding proteins such as the splicing factor MBNL1. Consequently, several alternative splicing defects have been identified in skeletal muscular biopsies from DM1 patients. Up to now, cellular models available for DM1 rely mainly on primary cultures of skeletal muscle cells derived from DM1 patients. However, several difficulties, such as a limited in vitro proliferation, may limit the use of primary cells, especially considering drug screening approaches for this incurable disease. Methods: Based on recent protocols allowing the conversion of human pluripotent stem cells into skeletal muscle cells without genetic modifications, our goal was to evaluate the potential offered by DM1 specific hiPSCs to better understand the effect of DM1 mutation on the generation and the maintenance of skeletal muscle cells. Results: Altogether, our results demonstrate the potential offered by DM1 specific hiPSC-derived skeletal muscle cells to phenocopy and decipher new molecular pathophysiological mechanisms. Conclusion: Furthermore, this new cellular system holds great promises to identify new compounds capable to target the RNA toxicity associated with DM1 mutation.

PS1Group1-145 / #367A CASE OF FACIOSCAPULOHUMERAL MUSCULAR DYSTROPHY TYPE 2 WITH NOVEL FRAMESHIFT MUTATION OF SMCHD1 GENE IN KOREA

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Jung Hwan Lee¹, Moon-Woo Seong², Chang-Seok Ki³, Young Chul Choi⁴

¹Department Of Neurology, Ewha Womans University Mokdong Hospital, Seoul, KR;²Department Of Laboratory Medicine, Seoul National University Hospital, Seoul, KR;³Department Of Laboratory Medicine And Genetics, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, KR;⁴Department Of Neurology, Gangnam Severance Hospital, Yonsei University College of Medicine, Seoul, KR

Background: Facioscapulohumeral muscular dystrophy 2 (FSHD2) is a genetic muscular disorder characterized by DNA hypomethylation on the 4q-subtelomeric macrosatellite repeat array, D4Z4. DNA hypomethylation is caused by heterozygous mutations in the gene encoding structural maintenance of chromosomes flexible hinge domain containing 1 (SMCHD1). In Korea, there are no reports of patient with FSHD2. We reported a first case of FSHD2 in Korea. Methods: A 40-year-old male visited to our clinic for asymmetric upper and lower extremity weakness. He said that His father, dead due to liver cirrhosis, and elder brother were similar with him. He was normal at birth and presented normal development. He presented asymmetric arm weakness after the age of 10 and leg weakness after the age of 24. And, he also presented winged scapula and Popeye arm. On neurologic examination, we could observe bilateral facial weakness, asymmetric proximal dominant arm and leg weakness. Results: First, we performed conventional Southern blot analysis but D4Z4 repeat size was 12, which means normal. Then, we performed whole exome sequencing and found novel frameshift mutation (c.3801delG, p.Glu1267Aspfs*5) of SMCHD1 gene. Then, we re-checked size of D4Z4 repeat with 4qA haplotype and performed hypomethylation assay of D4Z4 repeat region. As a result, he has homozygous 4qA haplotype and mild reduced D4Z4 repeat size (41kb/39kb), and reduced D4Z4 methylation ratio (14.6%). So, we report a first case of FSHD2 in Korea. Conclusion: For rapid and accurate diagnosis of FSHD2 patients, the genetic analysis of D4Z4 haplotype and methylation is very important and needed to add for diagnostic step for FSHD.

PS1Group1-146 / #1012ASYMMETRIC WEAKNESS IN HMGCOA REDUCTASE ANTIBODY NECROTIZING MYOPATHY

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Madhu Soni

Neurological Sciences, Rush University Medical Center, Chicago, IL, US

Background: Objectives: To report a case of asymmetric weakness in statin-associated HMGCoA reductase antibody necrotizing myopathy, and to heighten awareness of the potential etiology. Background: Necrotizing myopathy due to statins and other drug-induced or immune-mediated triggers typically presents with symmetric, proximal weakness that can be abrupt in onset and aggressive in its course, requiring prompt recognition to stop the offending agent, institute immunotherapy if necessary and provide the appropriate supportive care. A case is described here of an elderly gentleman with prominent, asymmetric proximal upper extremity weakness that did not improve with immunotherapy. Methods: Case Report: A 74- year-old, previously active, man was brought in for progressive weakness over 6 weeks that started abruptly. Symptoms started with symmetric, painless proximal lower extremity weakness limiting ambulation and use of stairs, and contributed to falls. The weakness progressed to involve the upper extremities, starting on the left where there was self-limited pain in the shoulder associated with weakness. Weakness in the right upper extremity was painless. Dysphagia and dyspnea also developed. The patient had been on daily atorvastatin for 10 years. Exam was notable for asymmetric right arm abduction weakness of 0/5 compared to 3/5 contralaterally. He had moderate weakness of neck flexion and bilateral hip flexion, and was unable to stand without assistance. Work up included a left quadriceps muscle biopsy that revealed an active, necrotizing myopathy. HMGCoA reductase Ab was elevated. The patient was admitted for IVIG treatment and received prednisone 60 mg orally, along with physical and occupational therapy. Results: After two courses of IVIG, a month apart, his strength markedly improved with resolution of weakness in the neck and left upper extremity and mild residual weakness in the proximal lower extremities. Right arm abduction remained 0/5. He denied pain, including with passive movement of the arm at the shoulder. Shoulder xray revealed no significant abnormalities. Due to the discrepancy in right arm abduction, despite improvement in the remainder of his strength, a shoulder MRI was obtained and revealed a large tear of the right supraspinatus tendon and a moderate tear in the biceps. Conclusion: Asymmetric weakness is atypical in statin-associated HMGCoA reductase necrotizing myopathy and should trigger consideration for alternative, non-neurologic causes that may warrant an alternative treatment approach. In this case, a previously undiagnosed painless rotator cuff tear was the cause of the right arm abduction weakness that was refractory to immunotherapy for the underlying necrotizing myopathy. Heightened awareness and identification of potential co-exising orthopedic conditions and complications is essential to guide appropriate treatment and avoid unnecessary additional immunotherapy in immune-mediated myopathies.

PS1Group1-147 / #809CAN NECK FLEXION WEAKNESS PREDICT CHANGES IN SWALLOWING AND COUGH PEAK FLOW IN PATIENTS WITH MYOTONIC DYSTROPHY TYPE 1?

Topic: Group 1 – Muscle Diseases of Genetic Origin and Acquired Myopathies: Clinical Features, Pathophysiology, Therapy

Charlotte Massey¹, Jodi E. Allen², Umesh Vivekananda³, Nikoletta Nikolenko⁴, Cecilia Jimenez-Moreno⁴, Chris Turner⁵