Presentation of a kindred with familial medullary thyroid carcinoma and Cys611Phe mutation of the RET proto-oncogene demonstrating low grade malignancy.
Frequency of the Cys611Tyr (TGC-TAC) mutation was significantly increased in this region of Portugal, due to the fact that three apparently unrelated MEN2A/FMTC families, out of the five in which mutations were identified, harboured this specific mutation.