A 15-day-old male neonate presented with failure to thrive, recurrent vomiting and symptoms of shock. On examination, severe dehydration is noted. He has normal genitalia along with precocious development of pubic hair, phallic enlargement and accelerated skeletal maturation. BP of the child was normal. Lab findings revealed hyponatremia and hypokalemia, increased serum 17 -hydroxyprogesterone and increased urinary pregnanetriol. A biopsy from the adrenal gland was taken. Which of the following is the most likely enzyme deficiency in the above patient: -

This is a case of congenital adrenal hydroxylase deficiency. In this case, it is due to 21-hydroxylase deficiency. The most common form is 21-hydroxylase deficiency (CYP21). 21-hydroxylase deficiency in males is generally not identified in the neonatal period because the genitalia are normal. If the defect is severe and results in salt wasting, these male neonates present at age 1-4 weeks with failure to thrive, recurrent vomiting, dehydration, hypotension, hyponatremia, hyperkalemia, and shock (classic salt-wasting adrenal hyperplasia). Patients with less severe deficiencies of 21-hydroxylase present later in childhood because of the early development of pubic hair, phallic enlargement, or both, accompanied by accelerated linear growth and advancement of skeletal maturation (simple virilizing adrenal hyperplasia).