Large-scale analysis of mutations in RET exon 16 in sporadic medullary thyroid carcinomas in Japan

Germline mutations in the RET proto-oncogene are the cause of multiple endo crine neoplasia type 2 (MEN 2A and 2B) and familial medullary thyroid carci noma (FMTC), Some cases of sporadic medullary thyroid carcinoma (MTC) have also been reported to have mutations in the RET gene. However, two previous reports have given discrepant results on the frequency of the mutations in RET in sporadic MTCs in Japan. To clarify this problem, we analyzed mutati ons in RET exon 16 in 72 sporadic MTCs hg means of the two methods used in the previous studies, direct sequencing and polymerase chain reaction-restr iction fragment length polymorphism (PCR-RFLP), Mutations in exon 16 were d etected in only 2 of 72 cases of sporadic MTC. These results suggest that w hen a MTC has a mutation in RET exon 16, it is more likely to be a heredita ry MTC than a sporadic one in Japan.