[Prenatal diagnosis of mannosidosis using chorion villi]

The prenatal diagnosis of mannosidosis was carried out in one at-risk fetus by the analysis of chorionic villi obtained after 9 weeks of pregnancy. The diagnosis was based on the absence of acid alpha-mannosidase activity as determined by specific enzyme assay. The activity of two other lysosomal hydrolases (beta-galactosidase and beta-hexosaminidase) in chorion biopsy specimen was similar to the control values. The enzymatic diagnosis was confirmed after studies of fetal tissue.