Özet:

Objectives: Multiple endocrine neoplasia type 2 (MEN2) syndrome is associated with germ-line missense mutations in RET proto-oncogene, inherited in an autosomal dominant manner. Approximately 90% of RET mutations were shown to develop medullary thyroid carcinoma (MTK). Genetic testing is accomplished through RET mutation screen and asymptomatic first degree relatives of index cases are recommended to be tested for preventative surgical operations. Thus, we aimed to perform clinical follow-up of a sporadic MTK case, as well as to carry out RET proto-oncogen genetic diagnosis on the index case and her two sons. Materials and Methods: Index case has been subjected to detailed clinical evaluations, as well as to pre- and post-operative hystopathological examinations. Routine clinical follow-up including neck ultrasonography and biochemical evaluations have been performed. RET proto-oncogene routine diag-nostic test was performed on 10, 11, 13-16th exons of the gene through PCR-amplification followed by Sanger sequencing. Exon with a mutation was screened on index cases’ two sons. Results: Clinical evaluations diagnosed index case as MTK. RET genetic screen revealed c.1891G>T (D631Y) in 11th exon confirming diagnosis. The two sons were found negative for RET gene mutations in their 11th exons. Conclusion: Genetic diagnosis both confirmed clinical diagnosis of the index case and showed that the sons are healthy. This is the first report of a D631Y mutation in a case of sporadic medullary thyroid cancer without pheochromocytoma in the literature.

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