MC2R and chronic primary adrenal insufficiency: Several genetic causes of adrenal hypoplasia (NR0B1/dosage-sensitive sex reversal, adrenal hypoplasia congenita critical region, on the X chromosome, gene 1 [DAX-1], NR5A1/SF-1, CDKN1C gene defects), congenital lipoid adrenal hyperplasia (CYP11A1, STAR gene defects), familial glucocorticoid deficiency (FGD) and FGD-like conditions (MC2R [FGD1], MRAP [FGD2], STAR, MCM4, NNT, TXNRD2 gene defects) and adrenal destruction (AIRE, ABCD1, PEX1, LIPA gene defects) are now well established (5, –, 16).