RET and medullary thyroid gland carcinoma: Ten studies (n = 10/14; N = 3760 patients) analyzed the features of MTC amid MEN2 confirmation [35,38,39,40,41,43,44,46,47,48]; the highest prevalence of MTC reached 100% [47] and varied according to the RET pathogenic variant, with maximum rate in p.Met918Thr (100%) and p.Cys634Phe/Gly/Arg/Ser/Trp/Tyr (88.9%) [35].