First-trimester prenatal diagnosis of mucolipidosis II (I-cell disease) by chorionic biopsy.

We investigated the possibility of mucolipidosis type II (ML II) prenatal diagnosis by lysosomal enzyme determination on trophoblast biopsy obtained at 10 weeks of gestation in two pregnancies at risk. Diagnosis of ML II was made in both cases on fresh chorionic villi on the basis of depressed beta-galactosidase activity, and after abortion, the diagnosis was confirmed on fresh fetal tissues and on cells cultured from trophoblast and fetuses. We stress the importance of culturing cells from the trophoblast biopsy to ensure a reliable diagnosis.