We identified RET mutations in seven of 13 MTCs: five RET-positive cases revealed a mutation in exon 16 (M918T) and two a mutation in exon 10 (C618S and C620S). In four of the RET-positive cases, the mutation was inherited, out of which three were reportedly associated with a multiple endocrine neoplasia type 2 (MEN2) syndrome, i.e. MEN2A (C618S), MEN2A/familial MTC (FMTC) (C620S), and MEN2B (M918T).