Development of the ovaries and internal female reproductive organs is unaffected. Three quarters of affected infants have the severe salt-losing form, which is associated with vomiting and, from about 7 days after birth, signs of hyponatremic dehydration and hyperkalemia. The gene for 21 hydroylase is termed CYP 21 and is located on 17beta-Hydroxysteroid Dehydrogenase Deficiency. This defect impairs the conversion of androstenedione to testosterone in the testis. Sixty cases have been reported from one inbred community in the Gaza Strip.
Inheritance is autosomal recessive.
Most XY cases have either ambiguous or female genitalia. In that group, at least 14 mutations in the 17beta-hydroxysteroid reductase 3 gene have been detected.