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Classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency, simple virilizing form
The simple virilizing form of classical congenital adrenal hyperplasia due to 21-hydroxylase deficiency (classical 21 OHD CAH; see this term) is characterized by genital ambiguity and virilization of the external genitalia in females, hypocortisolism and precocious pseudopuberty without salt-wasting.
ORPHA:315311Classification level: Subtype of disorder
- Classic 21-OHD CAH, simple virilizing form
- Prevalence: 1-9 / 100 000
- Inheritance: Autosomal recessive
- Age of onset: Infancy, Neonatal
- ICD-10: E25.0
- OMIM: -
- UMLS: -
- MeSH: -
- GARD: -
- MedDRA: -
The prevalence is approximately 1/40,000 as it accounts for about 25% of classic CAH cases.
Girls present at birth with ambiguous genitalia and variable levels of virilization. They have a normal uterus but abnormal vaginal development. The external genitalia in boys are normal. Precocious pseudopuberty, manifesting with various symptoms including accelerated growth velocity and bone maturation, is also present in both sexes. Unlike the salt wasting form of classical 21 OHD CAH, the simple virilizing form has no symptoms of dehydration, but has a glucocorticoid deficiency requiring life-long substitution therapy and carrying a life-long risk of adrenal crisis.
The disease is caused by a mutation in the CYP21A2 gene located on chromosome 6p21.3. As a result of this mutation, the synthesis of aldosterone is normal while the synthesis of cortisol is abolished. The adrenal glands are overstimulated and this leads to an overproduction of androgens.
The disease follows an autosomal recessive pattern of inheritance.