RET and medullary thyroid gland carcinoma: The major somatic mutation (Met918Thr) localised in the tyrosine kinase domain in exon 16 of RET (Marini et al, 2006) has been associated to a worse clinical outcome in sporadic MTC when compared with tumours that did not harbour this mutation (Zedenius et al, 1994, 1995; Wohllk et al, 1996; Schilling et al, 2001).