This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Genetic and genetic disorders, Subject name: Pediatrics
[{'content': 'Most common enzyme deficiency in congenital adrenal hyperplasia is \nSelect and explain. \nA. 3 beta hydroxylase, B. 11 beta hydroxylase, C. 17 hydroxylase, D. 21 alfa hydroxylase', 'role': 'user'}, {'content': 'Answer: D \nExplanation: congenital adrenal hyperplasia is a group of autosomal recessive defects in steroid synthesis characterised by deficiency of adrenocoical hormones The commonest form of congenital adrenal hyperplasia accounting for about 90% of cases is due to deficiency of 21-alpha hydroxylase It is associated with diminished synthesis of coisol and aldosterone Reference: Ghai TB of pediatrics 8th edition pg 526', 'role': 'assistant'}]