MEN2B is caused by mutations in the RET gene, and is associated with medullary thyroid carcinoma, pheochromocytoma, marfanoid habitus, and multiple mucosal neuromas involving the face (42, 43), as compared to CS, which presents with multiple neuromas affecting acral sites (41). This evidence concerns the gene RET and hereditary pheochromocytoma-paraganglioma.