On the other hand, of the 5 cases of MEN2B with an M918T mutation (de novo mutation in 3 patients), 2 had MTC, 2 had MTC and PHEO, 1 had mixed medullary-follicular carcinoma, and all presented with a typical facies, numerous mucosal neuromas in the anterior tongue, lips, and buccal mucosa, and a Marfanoid habitus (Table 1). This evidence concerns the gene RET and medullary thyroid gland carcinoma.