Characterization of gene rearrangements and gene conversion events in the 21-hydroxylase gene.

Congenital adrenal hyperplasia (CAH) is an inherited disorder of steroidogenesis with a wide spectrum of expression. In about 95% of cases, the disease is the result of 21-hydroxylase deficiency, an autosomal recessive condition that maps to the major histocompatibility complex (MHC) on 6p21.3 (1). Classical CAH results in excessive androgen production. Females with this disorder are frequently diagnosed at birth because of ambiguous development of external genitalia, whereas males may not present until age 4-7 when they begin to manifest inappropriate virilization. Approximately 30% of individuals with classical CAH have this simple virilizing form of the disease. The remaining 70% in addition manifest the potentially life-threatening salt-wasting form of classical CAH characterized by an inability to retain dietary sodium.