Somatic mutations in the RET protooncogene in Japanese and Chinese sporadic medullary thyroid carcinomas

Objective Despite advances in the understanding of the genotype - phenotype correlation in multiple endocrine neoplasia type 2A and 2B (MEN 2A, MEN 2B), and familial medullary thyroid carcinoma (FMTC), the frequency and prognostic relevance of RET protoonco-gene mutations in sporadic medullary thyroid carcinomas (MTCs) remain controversial. Methods To study somatic mutations in the RET protooncogene in Japanese and Chinese sporadic MTCs and to comparatively analyze the correlation between RET mutation and tumor differentiation, we investigated somatic mutations in the RET protooncogene in 20 Japanese and 20 Chinese sporadic MTCs by the polymerase chain reaction - restriction fragment length polymorphism (PCR- RFLP) method. Results Of the 40 sporadic MTCs, 13 had a point mutation in codon 918 of exon 16, a frequency of 32.5%. There was no significant difference in the frequency between Japanese and Chinese sporadic MTCs, as 3096 of the Japanese and 35% of the Chinese sporadic MTCs contained this mutation. We