Fluorimetric assay with a novel substrate for quantification of galactocerebrosidase (GALC) activity in dried blood spot specimens

Decreased galactocerebrosidase (GALC) enzyme activity may be indicative of Krabbe disease, a lysosomal storage disorder with devastating neurodegenerative consequences. Quantitative fluorimetric assays for GALC activity in isolated blood and skin cells have been described; however, no such assay has been described using dried blood spot (DBS) specimens.

We present data on characterization of the novel substrate and assay, including pH optimization and enzyme kinetics using a fluorimetric profile. Our results with this assay show a clear discrimination between GALC activities in samples from Krabbe disease patients versus presumed normal newborn samples.

Authors: Anirudh J. Ullal, Hong Pham, Rajendra Singh, Peter Ross, Carrie A. Graham, Scott M. Norton, Miriam H. Nuffer, Debbie S. Burns, Maria Escolar, Allen E. Eckhardt, Deeksha Bali, Vamsee K. Pamula.

Practical Laboratory Medicine.  Volume 18, January 2020, e00141.

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