Prenatal diagnosis of Sanfilippo disease type C using a simple fluorometric enzyme assay.

A new fluorogenic substrate, 4-methylumbelliferyl beta-D-glucosaminide, was used for the assay of acetyl CoA:glucosaminide N-acetyltransferase in chorionic villi, cultured villus cells, and amniocytes. Optimal conditions for the assay and the ranges of enzyme activity were established for the various types of fetal cells. This simple fluorometric assay provides a reliable method for early prenatal diagnosis of Sanfilippo disease type C which is more convenient than current methods using radiolabelled substrates. The method was applied to amniotic fluid cells and fetal fibroblasts from an at-risk pregnancy in which an affected fetus was diagnosed by two-dimensional electrophoresis of glycosaminoglycans in the amniotic fluid.