MEN2A is characterized by medullary thyroid carcinoma, pheochromocytoma, and parathyroid hyperplasia, while MEN2B includes more aggressive medullary thyroid carcinoma, pheochromocytoma, and neuromas but lacks primary hyperparathyroidism [3,4,5,6,7]. This evidence concerns the gene RET and medullary thyroid gland carcinoma.