RET Proto-Oncogene Mutational Analysis in Patients With Medullary Thyroid Carcinoma

Abstract Background: The aim of this study was to identify germline mutation of the RET (rearranged during transfection) gene in patients with Medullary Thyroid Carcinoma (MTC) and their first-degree relatives to find pre-symptomatic carriers for possible prophylactic thyroidectomy.Methods and results: We examined all six hot spot exons (exons 10, 11, 13, and 14-16) of the RET gene by PCR and bidirectional sanger sequencing in 45 Iranian patients with MTC (either sporadic or familial form) from 7 unrelated kindreds and 38 apparently sporadic cases. First-degree relatives of RET positive cases were also genotyped for index mutation. Moreover, pre-symptomatic carriers were referred to the endocrinologist for further clinical management and prophylactic thyroidectomy if needed. Overall, the genetic status of all of the participants was determined by RET mutation screening, including 61 affected individuals, 22 pre-symptomatic carriers and 29 genetically healthy subjects. In 37.5% (17 of 45) of the MTC referral index patients, seven distinct RET germline mutations were found, including p.C634R (35.3%), p.M918T (17.6%), p.C634Y (11.8%), p.C634F (5.9%), p.C611Y (5.9%), p.C618R (5.9%), p.C630R (5.9%), p.L790F (5.9%) and an uncertain variant p.V648I (5.9%). Conclusion: RET mutation detection is a promising/golden screening test and provides an accurate pre-symptomatic diagnostic test for at-risk carriers (the siblings and offspring of the patients) to consider prophylactic thyroidectomy. Thus, mutation screening of the RET hot spot exons could be suggested for any MTC patient to find pre-symptomatic RET carriers in their relatives.