21-hydroxylase deficiency congenital adrenal hyperplasia.

Congenital adrenal hyperplasia (CAH) results from an enzymatic block at any stage in the synthesis of cortisol. All enzyme defects causing CAH are autosomal recessive traits. It is a relatively common disease, occurring in 1 in 5000 to 1 in 15,000 births in most populations. Since the isolation of the gene responsible for steroid 21-hydroxylase deficiency (involved in about 90% of the cases of CAH) in 1984, knowledge of the specific mutations that cause the different forms of CAH has grown rapidly. Defects in the encoding gene have been confirmed as the basis of endocrine disease in the case of all but one of the adrenal steroidogenic enzymes. Analysis of DNA obtained by chorionic villus sampling in early pregnancy permits prenatal diagnosis and treatment of 21-hydroxylase deficiency CAH. The correlation between the clinical expression of endocrine disease and the mutations of the primary structural gene is not absolute. Clinicians cannot accurately predict the course of the disease or make therapeutic decisions based on the genotype alone. We will review the various forms of clinical presentation of 21-hydroxylase CAH, its etiology, diagnosis, molecular genetics, and treatment.