Abstract

PIP: Mucopolysaccharidosis Type I (Hurler's syndrome) was diagnosed in an 18 week old fetus of a woman with 1 affected child by direct assay of glycosaminoglycans in amniotic fluid. Subsequently the fetus was aborted by hysterotomy and diagnosis was confirmed by analyzing glycosaminoglycans in fetal liver, electron micrographs isozymes of galactosidases, and fetal skin sulfate turnover. In this case the amnio tic fluid contained 78% dermatan and heparan sulfates. The fetal liver contained 28.8% dermatan sulfate and 62.4% heparan sulfate among the soluble glycosaminoglycans. Some translucent lysosomal vacuoles with osmiophilic inclusions were evident in liver but not in central nervous system. Isozymes A and B of alpha-galactosidase and beta-galactosidase- B were very low in fetal tissues compared with age-matched controls. 5 other lysosomal enzymes were slightly elevated upon assay with fluorescent substrates. Sulfate turnover studies in cultured fetal skin cells showed excessive accumulation but enhanced release rates in presence of pooled normal human serum (Hurler corrective factor). When these studies were done, the enzyme defect in Hurler's syndrome was known to be alpha-L-iduronidase, but no substrate was available commercially.