1ST-TRIMESTER DIAGNOSIS OF AN UNUSUAL CASE OF ALPHA-MANNOSIDOSIS

Chorionic villi obtained in the first trimester from a pregnancy at risk for alpha-mannosidosis were shown to have reduced alpha-mannosidase (EC 3.2.1.24) activity. The pregnancy was terminated and subsequent enzyme studies of the fetal tissues were consistent with the diagnosis of alpha-mannosidosis. Like the enzyme in the child's fibroblast, alpha-mannosidase of the chorionic villi from a pregnancy at risk for alpha-mannosidosis was activated by high substrate concentration and by Zn2+, and displayed a K(m) value two-fold higher than normal. Our results confirm that chorionic villi can be used for early prenatal diagnosis of alpha-mannosidosis.