Hereditary Transthyretin Amyloidosis- Clinical and Genetic Characteristics of a Multiracial South-East Asian Cohort in Singapore

Article type: Research Article

Authors: Chen, Zhiyong^{a; *} | Koh, Jasmine S.^a | Saini, Monica^a | Tay, Karine S.S.^a | Jayne Tan, Yi^a | Chai, Josiah Y.H.^a | Fam, Su Rong^a | Juraidah, A.R.^a | Lim, Peck Kee^a | Ng, Adeline S.L.^{a; c} | Prasad, Kalpana^a | Tan, Chai Beng^d | Umapathi, T^a | Verma, Kamal K.^a | Yong, Ming Hui^b | Yu, Chen^a | Ng, Peng Soon^a

Affiliations: [a] Department of Neurology, National Neuroscience Institute, Tan Tock Seng Hospital, Singapore | [b] Department of Neurology, National Neuroscience Institute, Singapore General Hospital, Singapore | [c] Duke NUS Graduate Medical School, Singapore | [d] Department of Neurology, Gleneagles Hospital, Singapore

Correspondence: [*] Correspondence to: Z. Chen, Department of Neurology, National Neuroscience Institute, 11 Jalan Tan Tock Seng, Singapore 308433, Singapore. Tel.: +65 63577171; Fax:+ 65 63577137; E-mail: [email protected].

Abstract: Background and aims:Studies of hereditary transthyretin amyloidosis (ATTRv amyloidosis) in South-East Asia are underrepresented in the literature. We report the unique phenotypic and genetic characteristics of this disorder in a multiracial South-East Asian cohort. Methods:Patients with genetically proven ATTRv amyloidosis were identified over a 13-year period (2007–2020) at the National Neuroscience Institute, Singapore. Clinical, laboratory, genotypic and electrophysiological features were retrospectively reviewed. Results:29 patients comprising Chinese, Malay, Burmese, Vietnamese and Indonesians with ATTRv amyloidosis were identified. Somatic neuropathy was the most common initial presentation, followed by carpal tunnel syndrome, autonomic dysfunction and cardiac dysfunction. ATTR-A97S (p.Ala117Ser) was the most common variant found in 14 patients, constituting 66.7%of ethnic Chinese patients and 48.3%of the entire cohort. Five patients had early-onset disease (age < 50 years) with the following variants: ATTR-V30M (p.Val50Met), ATTR-G47A (p.Gly67Ala), ATTR-S50I (p.Ser70Ile) and ATTR-A97S (p.Ala117Ser); one patient with ATTR-A97S (p.Ala117Ser) had isolated unilateral carpal tunnel syndrome with amyloid deposits identified on histological examination of the transverse carpal ligament. All early-onset patients had a positive parental history; two patients, with ATTR-S50I (p.Ser70Ile) and ATTR-Ala97Ser (p.Ala117Ser) respectively, demonstrated anticipation with mother-to-daughter inheritance. Amongst the 24 patients with late-onset disease (age≥50 years), two patients had novel variants, ATTR-G66D (p.Glu86Asp) and ATTR-A81V (p.Ala101Val) that were confirmed to be pathogenic based on the histological identification of transthyretin amyloid. Other identified variants included ATTR-V30M (p.Val50Met), ATTR-R34T (p.Arg54Thr), ATTR-S50I (p.Ser70Ile), ATTR-H88R (p.His108Arg) and ATTR-A97S (p.Ala117Ser). Conclusion:Our study further expands the genotypic and phenotypic knowledge regarding ATTRv amyloidosis.

Keywords: Amyloid neuropathies, familial, amyloidosis, hereditary, transthyretin-related, TTR protein, human

DOI: 10.3233/JND-210656

Journal: Journal of Neuromuscular Diseases, vol. 8, no. 4, pp. 723-733, 2021