A Novel Point Mutation of K-ras Gene Coexisted with Codon 12 Mutation

Objective:To detect the mutation status of K-ras gene in colorectal cancers and to assist the clinical treatments.Methods:DNA was extracted from fifteen formalin-fixed,paraffin-embedded tumor samples of colorectal cancers,and then the fragments containing codons 12,13 and codon 61 were amplified by PCR.The sequences were indentified by direct sequencing which is gold standard for the detection of mutation.Results:In the 15 samples of colorectal cancer patients,4 mutations were observed,with 2 in codon 12 and 2 in codon 13.Suprisingly,a novel point mutation at codon 42 of K-ras was found,and coexisted with mutation in codon 12.Conclusion:Except for codons 12,13,61 mutation,K-ras has other mutation at codon 42 with coexisted with codon 12 point mutation.