MC2R and familial glucocorticoid deficiency: The symptoms of neonatal CIAD are nonspecific, so a differential diagnosis is needed to exclude other diseases, such as congenital adrenal hyperplasia (CAH), congenital hypopituitarism, familial glucocorticoid deficiency (FGD), as well as mutations in genes for the ACTH receptor or genes related to ACTH synthesis, and especially mutations in genes responsible for FGD, a rare autosomal recessive disorder characterized by hyperpigmentation of the skin and mucosa, severe hypoglycemia, occasional seizures and coma, feeding difficulties, growth retardation, and infections.