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. The gene discussed is RET; the disease is Hirschsprung disease.