This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Pediatrics
In congenital adrenal hyperplasia, deficient enzyme is - most womon 
Select and explain. 
A. 11(3 hydroxylase deficiency, B. 21 a hydroxylase deficiency, C. 3a hydroxylase deficiency, D. 17a hydroxylase deficiency
B: 21 a hydroxylase deficiency
Answer: B: 21 a hydroxylase deficiency 
Explanation: Ans. is 'b' i.e., 21-a Hydroxylase Congenital adrenal hyperplasia (CAH) Group of AR disorder MC adrenal disorder in childhood Most common 21-hydroxylase deficiency In 21a-hyroxylese deficiency There is deficiency of mineralocoicoids & glucocoicoid. This leads to hypoglycemia, hyponatremia