Prenatal Diagnosis of Cystinosis

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. The pregnancy was terminated by hysterotomy. No cystine crystals were observed in any organ. The only tissue that was abnormal by phase or light microscopy was the retinal-pigment epithelium, in which vacuolization was observed. The diagnosis was confirmed because the nonprotein cystine content of the liver, placenta, kidney, thymus and spleen was 50 to 100 times greater than in control fetuses. Cell cultures were established from nine fetal organs, and all contained increased amounts of nonprotein cystine. (N Engl J Med 290:878–882, 1974)