Prenatal Diagnosis of Cystinosis

Abstract

We diagnosed cystinosis in an 18-week-old fetus on the basis of an increased content of nonprotein cystine in cultured amniotic-fluid cells. These cells did not contain cystine crystals, and the cystine concentration of cell-free amniotic fluid was normal. Thus, in utero diagnosis can only be made by measurement of the nonprotein cystine content of cultured amniotic-fluid cells.