RET and medullary thyroid gland carcinoma: Oncogenic activating point mutations can occur mainly in the extracellular domain, particularly in codon C634 of exon 11, in 609, 611, 618, or 620 of exon 10, and in M918 of exon 16, being RET exon 16 p. M918T mutation the most common and represents more than 75% of all RET somatic mutations found in MTC (42).