The most common cause of ambiguous genitalia in a newborn is –: (A) 21 hydroxylase deficinece, (B) 11 β – hydroxylase deficiency, (C) 17 α – hydroxyalse deficiency, (D) 3 β – hydroxysteroid deficiency
Answer is A. Congenital adrenal hyperplasia due to classic 21-Hydroxylase deficiency is the most common cause of ambiguous genitalia in the newborn. Virilization is apparent at birth in the female and within the first 2-3 years of life in the male.