Such genetic variants in the leptin-melanocortin signaling pathway are the cause of rare genetic diseases of obesity, including proopiomelanocortin (POMC) deficiency and leptin receptor (LEPR) deficiency, which are characterized by early-onset severe obesity and hyperphagia [13, 14, 16]. The gene discussed is POMC; the disease is hyperinsulinemic hypoglycemia, familial, 4.