Lymphocyte Galactocerebrosidase Activity by LC-MS/MS for Post-Newborn Screening Evaluation of Krabbe Disease.

Published

Journal Article

BACKGROUND: Deficiency of the lysosomal enzyme galactosylcerebrosidase (GALC) causes Krabbe disease. Newborn screening for Krabbe disease is ongoing, but improved methods for follow-up analysis of screen-positive babies are needed to better advise families and to optimize treatment. We report a new assay for the enzymatic activity of GALC in lymphocytes. METHODS: T lymphocytes were isolated from venous blood by magnetic bead technology. The assay used a close structural analog of the natural substrate and LC-MS/MS to quantify the amount of product with the aid of a chemically identical internal standard. RESULTS: The analytical range of the assay (ratio of assay response for the QC high standard to that from all non-enzymatic-dependent processes) was 20-fold greater than that for the conventional radiometric GALC assay. The LC-MS/MS could distinguish cells that were null in GALC from those that contained traces of active enzyme (down to 0.3% of normal). There was a good correlation between the level of residual GALC activity in lymphocytes and the severity of Krabbe disease. CONCLUSIONS: The new assay can measure small amounts of residual GALC activity in leukocytes with high accuracy compared to previous assays and can contribute, along with genotyping, biomarker analysis, and neurological imaging, a better plan for post-newborn screening follow-up for Krabbe disease.

Full Text

Duke Authors

Cited Authors

  • Liao, H-C; Spacil, Z; Ghomashchi, F; Escolar, ML; Kurtzberg, J; Orsini, JJ; Turecek, F; Scott, CR; Gelb, MH

Published Date

  • August 2017

Published In

Volume / Issue

  • 63 / 8

Start / End Page

  • 1363 - 1369

PubMed ID

  • 28592445

Pubmed Central ID

  • 28592445

Electronic International Standard Serial Number (EISSN)

  • 1530-8561

Digital Object Identifier (DOI)

  • 10.1373/clinchem.2016.264952

Language

  • eng

Conference Location

  • England