Analysis of mutations in KRAS and BRAF genes in colorectal cancer in Russian patients

Mutations in KRAS and BRAF genes in 80 colorectal cancer (CRC) samples from Russian patients were tested using two methods: 1) allele-specific real-time PCR (as-rt PCR) and 2) wild-type blocking PCR with Sanger sequencing (WTBS). material and methods. Sections of fresh frozen or formalin-fixed paraffin embedded tumor tissue from 80 patients were used in the study. Tumor tissue content was determined on H&E stained sections. Samples were first tested by as-rtPCR for common mutations of the KRAS gene (G12C, G12S, G12R, G12V, G12D, G12A, G13D) and mutations BRAFV600E. After that samples were evaluated in PCR with oligonucleotide blocking amplification of wild-type DNA for enrichment with mutant allele followed by Sanger sequencing of the PCR DNA (WTBS method). results. In 5 (6.3 %) cases samples had low tumor tissue content (