RET and medullary thyroid gland carcinoma: Together, HSCR-associated and MTC-associated RET mutations display distinct features, and, although the whole spectrum of biological effects by those RET mutations have not been fully elucidated, current consensus holds that HSCR is caused by inactivating mutations of the RET gene whereas MTC is induced by activating mutations of RET (Hansford and Mulligan, 2000).