This information is provided by the National Institutes of Health (NIH) Genetic and Rare Diseases Information Center (GARD).
Classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency (classic 21-OHD CAH) affects the adrenal glands which are responsible for producing specific hormones. There are two types of classic 21-OHD CAH, the salt-wasting form and the simple-virilizing form. Symptoms include abnormal development of the external sex organs in females (ambiguous genitalia), early puberty, and short stature. The salt-wasting form also may include the inability to retain salt and water. This can lead to dehydration, low blood pressure, and a life-threatening adrenal crisis. Classic 21-OHD CAH is caused by a genetic pathogenic variant in the CYP21A2 gene and is inherited in an autosomal recessive pattern. Diagnosis is based on the symptoms, blood hormone testing and may be confirmed by the results of genetic testing. Classic 21-OHD CAH can be diagnosed through a newborn screen. Treatment can prevent the more severe symptoms and may involve hormone replacement. in addition, some girls with abnormal genitalia may be offered surgery.
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