<prompt> Congenital Adrenal Hyperplasia is due to deficiency of:21 beta hydroxylase17 alpha hydroxylase5 alpha reductase17 beta reductase  <response>: a. 21 beta hydroxylaseRef: Nelsons 20e p 2714-2723, Ghai 8e p 526-527Most common cause of Congenital Adrenal Hyperplasia is 21 beta hydroxylase deficiency. 