Prenatal diagnosis and treatment of congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is a group of inherited disorders caused by enzyme deficiencies in steroid biosynthesis, which disrupt the conversion of cholesterol to cortisol. The most common form of CAH is 21-hydroxylase deficiency (21-OHD). In its severe form, 21-OHD causes prenatal virilization of external female genitalia. Through molecular genetic analysis of fetal DNA, defects in 21-OH synthesis can be diagnosed in utero. Genital ambiguity in females can be reduced or eliminated with prenatal dexamethasone treatment, which successfully suppresses fetal androgen production. Data from current, large cohort studies show that prenatal diagnosis and treatment are safe and effective.