Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency

Congenital adrenal hyperplasia due to 17 alpha-hydroxylase deficiency
Classification and external resources
OMIM	202110
DiseasesDB	1841
eMedicine	med/380
MeSH	D000312
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Congenital adrenal hyperplasia due to 17α-hydroxylase deficiency is an uncommon form of congenital adrenal hyperplasia resulting from a defect in the gene CYP17A1, which encodes for the enzyme 17α-hydroxylase. It produces decreased synthesis of both cortisol and sex steroids, with resulting increase in mineralocorticoid production. Thus, common symptoms include mild hypocortisolism, ambiguous genitalia in genetic males or failure of the ovaries to function at puberty in genetic females, and hypokalemic hypertension (respectively). However, partial (incomplete) deficiency is notable for having inconsistent symptoms between patients, and affected genetic (XX) females may be wholly asymptomatic except for infertility.

This form of CAH results from deficiency of the enzyme 17α-hydroxylase (also called CYP17A1). It accounts for less than 5% of the cases of congenital adrenal hyperplasia and is inherited in an autosomal recessive manner with a reported incidence of about 1 in 1,000,000 births.

The most common abnormal alleles of this condition impair both the 17α-hydroxylase activity and the 17,20-lyase activity of CYP17A1. Like other forms of CAH, 17α-hydroxylase deficiency impairs the efficiency of cortisol synthesis, resulting in high levels of ACTH secretion and hyperplasia of the adrenal glands. Clinical effects of this condition include overproduction of mineralocorticoids and deficiency of prenatal and pubertal sex steroids.

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