Congenital Adrenal Hyperplasia

Congenital Adrenal Hyperplasia (CAH) is a rare inherited disorder (autosomal recessive) that is caused by a deficiency in enzymes that are needed to produce cortisol and/or aldosterone.  There are several forms of CAH. The most common form, which affects ~90% of patients, is caused by a deficiency of 21-hydroxylase – an enzyme responsible for the production of adrenal steroids.  The effects of 21-Hydroxylase deficiency can be mild (non-classical CAH) or severe (classical CAH).  Classical CAH is typically diagnosed in infancy or early childhood. Non-classical CAH is more common and may be detected in childhood or adulthood.

CAH occurs in both males and females, but the effects on a patient are quite different. In females with severe classical CAH, infants are often born with ambiguous genitalia, while males may show no outward signs of the condition. Adrenal crisis, a life-threatening condition that occurs when the body cannot produce cortisol in response to stress, is a risk in both males and females with classical CAH.  For this reason, all newborns in the US and in many other countries are screened for classical CAH at birth.

Despite newborn screening, exact estimates of the number of patients affected by CAH in the US vary. It is estimated that the incidence of CAH is between 1:10,000 and 1:20,000 births, with some ethnic groups having slightly higher incidence rates.

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