RET and medullary thyroid gland carcinoma: These studies have described an increased prevalence of the RET polymorphisms G691S (exon 11, rs1799939), L769L (exon 13, rs1800861), S836S (exon 14, rs1800862), and S904S (exon 15, rs1800863) in individuals with hereditary or sporadic MTC when compared with the population [17,57,60–62].