RET and neoplasm: Tumor tissue mutational status was known for four (57.1%) of the E-MTCs: one case was positive for the two RET polymorphisms Gly691Ser (rs1799939) and Arg982Cys (rs17158558), other two cases showed the previous two RET variants combined with the somatic Met918Thr mutation (p.G691S/M918T/R982C compound genotype), whereas the last one was both RET and RAS wild-type.