Point Mutations of ras and Gsα Subunit Genes in Thyroid Tumors

We studied 43 thyroid tumors including 5 adenomatous goiters, 7 follicular adenomas, 22 papillary carcinomas, and 9 medullary carcinomas with regard to the presence of point mutations in the genes of Gs alpha subunit (Gsα), Gi2 alpha subunit (Gi2α), H‐ras, K‐ras, and N‐ras by a polymerase chain reaction‐direct sequencing method. An adenomatous goiter and a follicular adenoma showed double mutations at codon 227 and 231, and 4 papillary carcinomas showed mutation at codon 231 of the Gsα gene. An adenomatous goiter, a follicular adenoma, and a papillary carcinoma showed a missense mutation in codon 13 of the K‐ras gene. There were no such missense mutations of these G‐protein or ras genes in medullary carcinomas. These data indicate that the genetic events involved in the oncogenesis of parafollicular C‐cells are different from those of thyroid follicular cells, in which missense mutations of Gsα and ras genes seem to play important roles in tumorigenesis.