First trimester diagnosis of Gaucher disease in a fetus with trisomy 21.

A 38-year-old lady, who had a previous infant with type 2 Gaucher disease, underwent prenatal diagnosis by chorionic villus sampling at 9 weeks' gestation. Results on the fresh villus revealed a 47,XY,+21 karyotype and a marked deficiency (2 per cent of control) of beta-glucosidase activity. Following termination, villus material was cultured which initially revealed only a partial enzyme deficiency and a normal female karyotype, i.e., maternal cells. A subsequent culture contained 47,XY,+21 cells which were deficient in beta-glucosidase activity, thus confirming the diagnosis. The results in this interesting case illustrate the potential dangers of maternal cell contamination in cultured villus cells.