POMC and classic congenital adrenal hyperplasia due to 21-hydroxylase deficiency: In the most common form, CAH due to 21-hydroxylase deficiency, diminished cortisol production leads to increased production of adrenocorticotropic hormone (ACTH) by the adrenal gland, thereby resulting in the overproduction of adrenal precursor steroids and adrenal androgens [3].