A new germline ala641thr variant in the transmembrane domain of the ret gene associated with medullary thyroid cancer

Introduction. The RET proto-oncogene is the most well-known gene involved in medullary thyroid cancer (MTC). The associations between specific RET mutations and the age of onset and aggressiveness of MTC and the presence or absence of other endocrine neoplasms such as pheochromocytoma or hyperparathyroidism have been well documented. When a new mutation is identified in the RET gene, defining that mutation’s codon-specific risk level is important in the management of patients with MTC. Case Report. Here, we present the first report of a patient with a germline variant of Ala641Thr, in the transmembrane domain of the RET gene. A 37-year-old female presented with an anterior neck mass, which was confirmed to be MTC by biochemical tests and pathologic findings. The patient had no identifiable family history of MTC or multiple endocrine neoplasia syndromes. Histology revealed a single unilateral MTC lesion (21 mm × 16 mm) in the right thyroid lobe without cervical lymph node metastasis. Genetic testing revealed a germline Ala641Thr missense mutation in the RET gene. The RET gene variant was inherited by one of her children. Conclusion. Although this novel variant has unknown clinical significance at present, the causative role of this genetic variant in MTC pathogenesis could be clarified by further molecular structure-function studies and additional clinical cases showing a genotype-phenotype relationship.