Journal of Inherited Metabolic Disease

, Volume 19, Issue 3, pp 278–285

A fluorimetric enzyme assay for the diagnosis of sanfilippo disease type A (MPS IIIA)


  • E. A. Karpova
    • Department of Clinical GeneticsErasmus University
  • Ya. V. Voznyi
    • Institute of Organic Chemistry
  • J. L. M. Keulemans
    • Department of Clinical GeneticsErasmus University
  • A. T. Hoogeveen
    • Department of Clinical GeneticsErasmus University
  • B. Winchester
    • Division of Biochemistry and GeneticsInstitute of Child Health
  • I. V. Tsvetkova
    • Institute of Biomedical Chemistry
  • O. P. van Diggelen
    • Department of Clinical GeneticsErasmus University

DOI: 10.1007/BF01799255

Cite this article as:
Karpova, E.A., Voznyi, Y.V., Keulemans, J.L.M. et al. J Inherit Metab Dis (1996) 19: 278. doi:10.1007/BF01799255


4-Methylumbelliferyl-α-d-N-sulphoglucosaminide (MU-α-GlcNS) was synthesized and shown to be a substrate for the lysosomal heparin sulphamidase. Sanfilippo A patients' fibroblasts (n=42) and lymphocytes (n=1) showed 0–3% of mean normal heparin sulphamidase activity; in total leukocytes from patients (n=8) sulphamidase activity was clearly deficient. In fibroblasts from obligate heterozygotes for Sanfilippo A, the sulphamidase activity was reduced in 9 out of 10 cases. Heparin sulphamidase desulphates MU-αGlcNS to MU-αGlcNH2 and further hydrolysis during a second incubation is required to liberate 4-methylumbelliferone, which can be measured. Yeastα-glucosidase, which has low but sufficientα-glucosaminidase activity, was used to hydrolyse the reaction intermediate MU-αGlcNH2 to release 4-methylumbelliferone and free glucosamine.

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© SSIEM and Kluwer Academic Publishers 1996