Digital Microfluidic Platform for Multiplexing Enzyme Assays: Implications for Lysosomal Storage Disease Screening in Newborns

• Published in: Clinical chemistry (Baltimore, Md.) Vol. 57; no. 10; pp. 1444 - 1451
• Main Authors: SISTA, Ramakrishna S, ECKHARDT, Allen E, MILLINGTON, David S, PAMULA, Vamsee K, TONG WANG, GRAHAM, Carrie, ROUSE, Jeremy L, NORTON, Scott M, SRINIVASAN, Vijay, POLLACK, Michael G, TOLUN, Adviye A, BALI, Deeksha
• Format: Journal Article
• Language: English
• Published: Washington, DC American Association for Clinical Chemistry 01.10.2011; Oxford University Press
• Subjects: alpha-Galactosidase - blood; alpha-Glucosidases - blood; Analytical, structural and metabolic biochemistry; Automation; Biological and medical sciences; Clinical Enzyme Tests - instrumentation; Disease; Fabry Disease - diagnosis; Fluorometry; Fundamental and applied biological sciences. Psychology; Glycogen Storage Disease Type II - diagnosis; Humans; Infant, Newborn; Investigative techniques, diagnostic techniques (general aspects); Lab-On-A-Chip Devices; Medical sciences; Medical screening; Methods; Microfluidic Analytical Techniques - instrumentation; Molecular biophysics; Neonatal Screening; Public health; Human; Assay; Multiplexing; Newborn; Enzyme; Clinical biology; Biochemistry; Molecular biology; Medical screening; Lysosomal storage disease
• ISSN: 0009-9147; 1530-8561
• DOI: 10.1373/clinchem.2011.163139

Newborn screening for lysosomal storage diseases (LSDs) has been gaining considerable interest owing to the availability of enzyme replacement therapies. We present a digital microfluidic platform to perform rapid, multiplexed enzymatic analysis of acid α-glucosidase (GAA) and acid α-galactosidase to screen for Pompe and Fabry disorders. The results were compared with those obtained using standard fluorometric methods. We performed bench-based, fluorometric enzymatic analysis on 60 deidentified newborn dried blood spots (DBSs), plus 10 Pompe-affected and 11 Fabry-affected samples, at Duke Biochemical Genetics Laboratory using a 3-mm punch for each assay and an incubation time of 20 h. We used a digital microfluidic platform to automate fluorometric enzymatic assays at Advanced Liquid Logic Inc. using extract from a single punch for both assays, with an incubation time of 6 h. Assays were also performed with an incubation time of 1 h. Assay results were generally comparable, although mean enzymatic activity for GAA using microfluidics was approximately 3 times higher than that obtained using bench-based methods, which could be attributed to higher substrate concentration. Clear separation was observed between the normal and affected samples at both 6- and 1-h incubation times using digital microfluidics. A digital microfluidic platform compared favorably with a clinical reference laboratory to perform enzymatic analysis in DBSs for Pompe and Fabry disorders. This platform presents a new technology for a newborn screening laboratory to screen LSDs by fully automating all the liquid-handling operations in an inexpensive system, providing rapid results.