Physiology The commonest cause of primary amenorrhea with ambiguous genitalia in a female with 46XX chromosome A 21 hydroxylase def. B 17 hydroxylase def. C 11 hydroxylase def. D Desmolase hydrolase def. 💡 Explanation The commonest cause of primary amenorrhea with ambiguous genitalia in a female with 46XX chromosome ✓ Correct Answer: A. 21 hydroxylase def.