<prompt> Most common cause of congenital adrenal hyperplasia?17- Hydroxylase deficiency11- Hydroxylase deficiency21- Hydroxylase deficiency16- Hydroxylase deficiency  <response>: Ans. c 21- Hydroxylase deficiency. Ref. Harrison, Principles of Medicine, 18th2178Congenital adrenal hyperplasia CAHFeatures3-beta-OH21-OH11-beta-OH17-alpha-OH1. Salt loss 2. Hypertension -3. Virilization--4. Ambigous genitaliaa Male__b Female-Note: 21-hydroxylase deficiency is the most common type of CAH 