[Detection of RET proto-oncogene Cys634Arg mutation, the cause of medullary thyroid carcinoma, in an Iranian child]

ABSTRACT

Medullary Thyroid Carcinoma [MTC] is hereditary in 25% of cases, and occurs primarily in an autosomal dominant manner. Thus, siblings and offspring of a patient diagnosed with a germline mutation are at a 50% risk for carrying the same mutation. Germline mutations of RET proto-oncogene is the known cause of almost all hereditary MTCs. Mutation analysis of RET is necessary for all apparently sporadic MTC patients. Cases Presentation In this study, three siblings diagnosed with MTC in a family were analyzed for RET mutations. The result of direct DNA sequencing showed Cys634Arg point mutation in all 3 of them. Screening of their offspring and 4th sibling resulted in identification of a 3-year-old boy as a mutation carrier. According to general consensus, he is at second risk level, which qualifies him for prophylactic total thyroidectomy. Molecular analysis of RET proto-oncogene should be done in a routine manner to differentiate hereditary MTC patients from sporadic ones. In case of finding a germline mutation, all siblings and offspring of the mutation carrier should be screened and asymptomatic carriers referred to total prophylactic thyroidectomy