General information (Source orphanet: http://www.orphanet.fr)
Congenital Adrenal Hyperplasia (CAH) refers to a group of hereditary diseases associated with either complete (classical form) or partial (non-classical) anomalies in the biosynthesis of adrenal hormones. The prevalence of the classical form associated with 21-hydroxylase deficiency has been estimated at 1/14,000. However, the non-classical forms are more common. CAH is transmitted as an autosomal recessive trait.
The classical form of the disease is characterized by insufficient production of cortisol, and of aldosterone (classical form with salt wasting), associated with overproduction of androgens by the hyperplasic adrenals. Overabundant male hormones leads to virilization of extrenal genitalia in baby girls, which will be surgically corrected. In the classical form, metabolic decompensation (dehydration with hyponatremia, hyperkalemia and acidosis associated with mineralocorticoid deficiency, and hypoglycemia associated with glucocorticoid deficiency) may be life-threatening from the neonatal period onwards.
Chronic hyperandrogenism may lead to accelerated growth during childhood, but advanced bone maturation may lead to a deficit in final height. Adults tend to be overweight and metabolic disturbances, bone anomalies and fertility problems may also be present. Non-classical forms are associated with later onset, during the peri- or postpubertal period, and manifest with signs of hyperandrogenism (acne, hirsutism, menstrual problems and infertility).
Newborn screening for 21-hydroxylase deficiency has been established in many countries, based on measurement of 17-hydroxyprogesterone levels. Identification of an index case should lead to testing of all family members and relatives. Prenatal diagnosis is possible through molecular analysis of fetal DNA.
Life-long hormone replacement therapy requires close follow-up (pediatric through to adulthood) and has improved the prognosis for patients by preventing complications associated with chronic hyperandrogenism and allowing normal fertility.