Medicine Disorders of Adrenal Gland 053f0435 Which is the most common variant of congenital adrenal hyperplasia? A 11b hydroxylase deficiency B 17a hydroxylase deficiency C 3b hydroxyl-steroid dehydrogenase D 21 hydroxylase deficiency High-Yield Explanation Mutations in CYP21A2 which leaads to 21 hydroxylase deficiency is the most prevalent cause of CAH responsible for 90-95% of cases.