Congenital adrenal hyperplasia owing to 21-hydroxylase deficiency

Congenital adrenal hyperplasia (CAH) owing to 21-hydroxylase deficiency is the most common cause of genital ambiguity in the newborn and is present in about 1 in 15,000 live births worldwide. The disease is further characterized in its classic salt-wasting form (similar to 75% of cases) by potentially Lethal adrenal insufficiency. A nonsalt-wasting form of classic CAH with 21-hydroxylase deficiency is also recognized by genital ambiguity in affected females and by signs of androgen excess in later childhood in males. Nonclassic CAH with 21-hydroxylase deficiency may be detected in 1% to 3% of populations and is often mistaken for idiopathic precocious pubarche in children or polycystic ovary syndrome m young women. This article presents an overview of clinical and genetic aspects of the various forms of CAH with 21-hydroxylase deficiency.