RET and familial medullary thyroid carcinoma: Multiple endocrine neoplasia type 2 (MEN2) is an autosomal dominant inherited endocrine malignancy syndrome, with an occurrence of approximately 1 in 30 000; MEN2 is due to germline mutations in the REarranged during Transfection (RET) proto-oncogene (OMIM: 164761) [1],[2], which includes the following three subtypes: MEN2A (OMIM: 171400); familial medullary thyroid cancer (FMTC; OMIM: 155240); and MEN2B (OMIM: 162300) [3].