Affiliations: Science and Technology Information Institute (IDICT), Miramar, Playa, Havana, Cuba | National Center of Medical Genetics, Cubanacan, Playa, Havana, Cuba | Immunoassay Center, Cubanacan, Playa, Havana, Cuba | Docent Paediatric Hospital “William Soler”, San Francisco Avenue, Altahabana, Boyeros, Havana, Cuba
Note:  Corresponding author: Dr. Ernesto Carlos González Reyes, Department of Neonatal Screening, Immunoassay Center, 134 Street and 25 Avenue, P.O. Box 11600, Cubanacan, Playa, Habana City, Cuba. E-mail: firstname.lastname@example.org
Abstract: BACKGROUND: Gaucher disease (GD) is a lysosomal storage disorder characterized by a deficiency of the lysosomal acid β-D-glucosidase (GBA). The aim of this study was to develop an ultramicro-fluorometric assay based on the method of Chamoles et al. for determining GBA activity in dried blood spots on filter paper (DBS). METHODS: The assay used 3-mm diameter blood spot and 8 mmol/l of 4-methylumbelliferyl-β-D-glucoside as enzymatic substrate. The reaction occurred in plates incubated at 37°C for 20 hours and the enzyme activity was expressed in μmol hydrolysed substrate/l blood/h. The fluorescence of the enzyme product was automatically measured in a fluorometer-photometer reader (SUMA Technology). RESULTS: The intra and inter-assay coefficients of variation were lower than 9 and 12%, respectively, and the recovery range was 97–109%.Three patients with GD were correctly diagnosed using the ultramicroassay. Healthy newborn DBS samples (n = 3003) from the National Neonatal Screening Program were analyzed, and the mean GBA activity was 5.7 μmol/l blood/h. Our assay showed high Pearson (n = 26; r = 0.99) and concordance correlations (ρc = 0.99) with the traditional method described by Chamoles et al. CONCLUSIONS: The analytical performance characteristics of our ultramicro-fluorometric assay suggest that it can be used in the diagnosis of GD in newborns and adults.