Prenatal diagnosis of Cockayne's syndrome.

Cockayne's syndrome (CS) was diagnosed prenatally by examination of amniotic cells cultured in vitro. RNA synthesis after irradiation with ultraviolet light was abnormal in cells from a fetus with CS but not in cells from a fetus which was normal. The procedure is simple and rapid and the outcome of the test in two cases (one positive, one negative) was unambiguous.