The RET proto-oncogene germlineloss of function mutations are associated with the development of HSCR, while gainof function mutations are responsible for development of various types of humancancer, including medullary thyroid carcinoma, multiple endocrine neoplasia type 2(MEN 2) and 2B, pheochromocytoma and parathyroid hyperplasia4. Here, RET is linked to multiple endocrine neoplasia type 2.