Prenatal diagnosis of cystinosis.

Cystinosis was diagnosed in a small quantity of cultured amniotic cells from a 22-week-old fetus by a modified pulse-labeling technique in which intracellular 35SL-cystine retention was measured. As a result of the above finding, the pregnancy was terminated by administration of prostaglandin. The diagnosis was confirmed when the nonprotein-free cystine content of the kidney, liver, placenta, spleen, thymus, and gut, as well as that of a large amount of cultured amniotic cells, was found to be 100-fold higher than normal levels.