Editor-In-Chief: C. Michael Gibson, M.S., M.D. 
- Severe 21-hydroxylase deficiency causes salt-wasting CAH, with life-threatening vomiting and dehydration occurring within the first few weeks of life. Severe 21-hydroxylase deficiency is also the most common cause of ambiguous genitalia due to prenatal virilization of genetically female (XX) infants.
- Moderate 21-hydroxylase deficiency is referred to as simple virilizing CAH; and typically is recognized as causing virilization of prepubertal children.
- Still milder forms of 21-hydroxylase deficiency are referred to as non-classical CAH and can cause androgen effects and infertility in adolescent and adult women.