Cushing’s syndrome can be ACTH-dependent or ACTH-independent, caused by an ACTH-secreting pituitary adenoma (Cushing’s disease) or by the ectopic secretion of ACTH determined by lung, pancreatic or thymic carcinoid tumors, respectively, by a secreting adrenal cortical adenoma or carcinoma of cortisol, iatrogenic (through corticotherapy), ACTH-independent bilateral macronodular adrenal hyperplasia and primary pigmented nodular adrenal disease. This evidence concerns the gene POMC and pituitary gland adenoma.