Purpose: New therapies for lysosomal storage diseases (LSDs) have generated interest in screening newborns for these conditions. We present performance validation data on a digital microfluidic platform that performs multiplex enzymatic assays for Pompe, Fabry, Hunter, Gaucher, and Hurler diseases.
Methods: We developed an investigational disposable digital microfluidic cartridge that uses a single dried blood spot (DBS) punch for performing a 5-plex fluorometric enzymatic assay on up to 44 DBS samples. Precision and linearity of the assays were determined by analyzing quality control DBS samples; clinical performance was determined by analyzing 600 presumed normal and known affected samples (12 for Pompe, 7 for Fabry and 10 each for Hunter, Gaucher and Hurler).
Results: Overall coefficient of variation (CV) values between cartridges, days, instruments, and operators ranged from 2 to 21%; linearity correlation coefficients were ≥0.98 for all assays. The multiplex enzymatic assay performed from a single DBS punch was able to discriminate presumed normal from known affected samples for 5 LSDs.
Conclusions: Digital microfluidic technology shows potential for rapid, high-throughput screening for 5 LSDs in a newborn screening laboratory environment. Sample preparation to enzymatic activity on each cartridge is less than 3h.
Keywords: 4-MU; 4-MU-α-Gal; 4-MU-α-IDS; 4-MU-α-IDU; 4-MU-α-gluc; 4-MU-β-Gluc; 4-methyl umbelliferone; 4-methylumbelliferyl α-d-galactopyranoside; 4-methylumbelliferyl α-d-glucopyranoside; 4-methylumbelliferyl α-l-iduronate-2-sulfate; 4-methylumbelliferyl α-l-iduronide; 4-methylumbelliferyl β-d-glucopyranoside; ALL; CDC; CLSI; Centers for Disease Control and Prevention; Clinical and Laboratory Standards Institute; DBS; DMSO; Digital microfluidics; Dried blood spot; GAA; GBA; GLA; GalNac; High throughput; IDS; IDU; LSDs; Lysosomal storage disease; Multiplex enzymatic assay; N-acetyl-d-galactosamine; NBS; Newborn screening; QCBP; QCH; QCL; QCM; RFU; acid α-galactosidase; acid α-glucosidase; acid α-l-iduronate-2-sulfatase; acid α-l-iduronidase; acid β-d-glucosidase; advanced liquid logic, Inc.; d-Sac; d-saccharic acid 1,4 lactone; dimethyl sulfoxide; dried blood spot; lysosomal storage diseases; methyl-β-cyclodextrin; newborn screening; quality control base pool, 0% cord blood+100% leukoreduced adult blood adjusted to 50.5% hematocrit on filter paper; quality control high, cord blood adjusted to 50.5% hematocrit on filter paper; quality control low, 5% cord blood+95% leukoreduced adult blood adjusted to 50.5% hematocrit on filter paper; quality control medium, 50% cord blood+50% leukoreduced adult blood adjusted to 50.5% hematocrit on filter paper; relative fluorescence units; β-MBCD.
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