Some centres use a stimulation test with the synthetic vasopressin analog desmopressin (1-deamino-8D-arginine vasopressin, DDAVP) as a means of differentiating CD from both pseudo-Cushing states and the ectopic ACTH-dependent Cushing's syndrome. The gene discussed is POMC; the disease is Cushing syndrome due to macronodular adrenal hyperplasia.