A Case of Sporadic Medullary Thyroid Cancer with RET G691S Polymorphism

Sporadic medullary thyroid carcinoma (MTC) is the most common f orm of MTC and somatic RET proto-oncogene mutations account for approximately 25% of the patients with sporadic MTC. However, other pathogeneses of sporadic MTC are still unclear. Not only RET mutation, but also polymorphisms of RET may have an association with sporadic MTC. We herein describe the association of MTC and RET proto-oncogene polymorphism. A 51-year-old man was diagnosed with MTC, which was incidentally found on a thyroid sonogram. The patient underwent total thyroidectomy and genetic mutational analysis of the RET gene. Genetic testing detected a polymorphism in codon 691 (G691S) on exon 11 of the RET proto-oncogene. His son and daughter had the same polymorphism. We report on this case along with a review of the related literature on