Increased frequency of the k-ras G12C mutation in MYH polyposis colorectal adenomas

Colorectal tumours from MYH polyposis patients display an excess of somatic G:C-->T:A transversions in the adenomatous polyposis coli gene. Here, we identify k-ras mutations in nine out of 54 (16.7%) MYH polyposis tumours. Their presence was associated with increased dysplasia and tubulovillous morphology (P=0.005). G:C-->T:A transversions in k-ras were significantly more frequent in MYH polyposis adenomas than in sporadic or familial adenomatous polyposis-associated tumours (Pless than or equal to0.002), and all resulted in a glycine-to-cysteine substitution at codon 12.