Development of a fluorometric microtiter plate based enzyme assay for MPS IVA (Morquio type A) using dried blood spots

Anirudh J Ullal; David S Millington; Deeksha S Bali

doi:10.1016/j.ymgmr.2014.10.004

Development of a fluorometric microtiter plate based enzyme assay for MPS IVA (Morquio type A) using dried blood spots

Mol Genet Metab Rep. 2014 Oct 22:1:461-464. doi: 10.1016/j.ymgmr.2014.10.004. eCollection 2014.

Authors

Anirudh J Ullal¹, David S Millington¹, Deeksha S Bali¹

Affiliation

¹ Duke Biochemical Genetics Laboratory, Department of Pediatrics, Duke Medicine, Durham, NC, USA.

Abstract

Mucopolysaccharidosis type IVA or Morquio type-A disease is a hereditary lysosomal storage disorder caused by deficient activity of the lysosomal enzyme N-acetylgalactosamine-6-sulfate sulfatase (GALNS). The disease is caused by lysosomal accumulation of unprocessed glycosaminoglycans (GAGs) that manifests with severe to mild skeletal and cardiopulmonary abnormalities. We have developed a modified microtiter plate-based enzyme activity assay using dried blood spots and a fluorescent substrate for measuring specific GALNS activity to identify patients with MPS IVA.

Keywords: 4-MU, 4-methylumbelliferone; 4-MU-β-gal-S, 4-methylumbelliferyl-β-d-galactopyranoside sulfate sodium salt; BSA, bovine serum albumin; DBS, dried-blood spot; ERT, enzyme replacement therapy; Fluorometric enzyme assay; GAG, glycosaminoglycan; GALNS, n-acetylgalactosamine-6-sulfate sulfatase; LSD, lysosomal storage disease; MPS; MPS IVA, mucopolysaccharidosis type IVA; Morquio type A; Mucopolysaccharidosis; β-Gal, β-galactosidase.