The aim of this study was to evaluate the presence of point mutations in codon 13 of the K-ras Bene in subjects who suffered from colorectal tumours with various clinical and histopathological classifications, to identify these mutations by DNA sequencing, and compare our results with conclusions of other studies. We investigated 55 specimens of colorectal carcinomas and 19 specimens of adenomatous polyps of the codon. Molecular biology investigationwas represented by PCRIRFLP analysis and PCR product sequencing. We found mutations in codon 13 in two cases of colorectal cancer (4 %) and one adenomatous polyp (5%). The frequency of these mutations found in the Czech Republic corresponds with the prevalence of these genetic changes predicted by larger generel population studies. In all three cases of mutations we identified a transition GGC~GAC. This „aggressive" type of mutations in the K ras Bene could significantly influence the survival prognosis of patients with colorectal cancer.

        Key words: colorectal carcinoma, adenomatous polyp, K-ras Bene, codon 13, DNA, PCR.