BRAF V600E mutation testing of colorectal tumors demonstrating aberrant MLH1 protein expression by IHC was the most common secondary tumor test, with 53% of laboratories performing the test; 15% of laboratories also applied the BRAF V600E test to endometrial tumors with aberrant MLH1 expression despite no evidence for its utility.
To verify the technical characteristics of the microarray system for the correct identification of the KRAS mutational status at the two hotspot codons 12 and 13 and of the BRAF(V600E) mutation in colorectal tumor, we selected 75 samples previously characterized by conventional and CO-amplification at Lower Denaturation temperature-PCR (COLD-PCR) followed by High Resolution Melting analysis and direct sequencing.
Secondly, considering the alternative possibility, we identified genes whose DNA hypermethylation was closely linked to BRAF(V600E) and CIMP in 235 primary colorectal tumors.
Recently, a V599E hotspot mutation within the BRAF gene was reported in a high percentage of colorectal tumors and significantly associated to defective mismatch repair (MMR).