Antenatal diagnosis in three pregnancies at risk for mannosidosis.

Three pregnancies were monitored in two families at risk for mannosidosis. a mannosidase and a fucosidase were determined on extracts from white blood cells of several members of these families, on fibroblast cell lines from the index cases and on uncultured and cultured amniotic cells of the foetuses. Two foetuses were diagnosed as affected and one as being free from the disease. The conclusions were confirmed on the affected foetuses after interruption of the pregnancy. The noticeable residual activity of a mannosidase found in some fibroblasts and cultured amniotic cells required complementary investigations (heat lability and dependency of substrate concentration) to reach a reliable diagnosis. Investigation of uncultured amniotic cells may give useful additional information.