RET and medullary thyroid gland carcinoma: MEN2A associates MTC, pheochromocytoma (PHEO), hyperparathyroidism (HPTH), cutaneous lichen amyloidosis and Hirschsprung’s disease, while MEN2B associates MTC, PHEO, ganglioneuromatosis of the aerodigestive tract, and facial, ophthalmologic and skeletal abnormalities.