RET and medullary thyroid gland carcinoma: Met918Thr RET mutation is the most common somatic mutation in sporadic forms of MTC, and its detection rate varies greatly (5–66%) in the published literature (Zedenius et al, 1994; Marsh et al, 1996; Romei et al, 1996; Wohllk et al, 1996; Bugalho et al, 1997; Scurini et al, 1998; Uchino et al, 1998, 1999; Dvorakova et al, 2008; Elisei et al, 2008).