Detection of Rare Mutations by Routine Analysis of KRAS, NRAS, and BRAF Oncogenes

Molecular genetic analysis of KRAS, NRAS, and BRAF genes was carried out in order to develop an optimal algorithm for detection of minor mutations. We analyzed 35 melanoma and 33 colorectal cancer specimens. Frequent G12D/V/A/C/S mutations were detected in KRAS. The most frequent BRAF mutation in melanoma was V600E, the percentage of rare mutations is significant for DNA diagnosis (24%). Identification of rare BRAF mutations 1790C -> G (L597R), 1798_1799delinsAA (V600K), 1798_1799delinsAG (V600R), and 1799_1800delinsAA (V600E) and NRAS mutation 38G -> T (G13V) was possible only by Sanger sequencing. The combination of real-time PCR and sequencing can improve analysis sensitivity and ensure concordance of the tested loci with the international recommendations.