Prenatal diagnosis of congenital adrenal hyperplasia owing to 21-hydroxylase deficiency

A non-invasive prenatal diagnostic method has been developed for congenital adrenal hyperplasia (CAH) owing to 21-hydroxylase deficiency. Excess fetal androgen production causes genital virilization in female fetuses affected with classical forms of CAH. In order to prevent genital ambiguity, prenatal dexamethasone treatment must be administered before the 9th week of gestation when genital organogenesis occurs. Invasive prenatal diagnostic methods do not yield a genetic diagnosis until after genital organogenesis begins. This new methodology could allow for the targeted treatment of affected female fetuses and avoid unnecessary prenatal treatment of males or unaffected females.