Congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) is an autosomal recessive condition characterized by an insufficient production of cortisol and mineraloactive hormones with a consequent hyperstimulation of hypothalamo-pituitary-adrenal feedback and an increase of androgens. Although the lack of different enzymes in adrenal steroidogenesis can be responsible for different forms of the disease, the deficiency of 21-hydroxylase is the more frequent defect. It is caused by mutations in CYP21 gene located on the short arm of chromosome 6 and it causes a heterogeneous phenotype characterized by a classical form (genitalia virilization in female, early onset acute adrenal insufficiency with salt wasting, precocious pseudopuberty, signs of hyperandrogenism), or by a simple virilizing form (presence of signs of hyperandrogenism without salt-loosing crises) or by a non-classic form evidenced only by mild to moderate signs of hyperandrogenism.