Prenatal diagnosis of lysosomal storage diseases using fetal blood

Lysosomal storage diseases are a rare but significant cause of non-immune hydrops fetalis (NIHF). In 17 cases of NIHF detected by ultrasound, the activity of five lysosomal enzymes was measured in leukocytes or plasma of 1 ml of fetal blood obtained by cordocentesis. By this approach seven lysosomal storage diseases known to present with hydrops fetalis can be diagnosed. In this series one case of mucopolysaccharidosis VII (M. Sly) was diagnosed at 20 weeks' gestation. The other samples allowed the establishment of reference ranges for lysosomal enzymes associated with NIHF in fetal blood. We conclude that, also in view of the poor prognosis of lysosomal storage diseases presenting with hydrops fetalis, the use of fetal blood for the early and fast biochemical diagnosis of these diseases is a valuable supplement in the diagnostic work-up and the management of NIHF.