BRAF CODON 600 – COLON CANCER
Gene Symbol: BRAF
Chromosomal Locus: 7q34
Protein: v-raf Murine Sarcoma Viral Oncogene Homolog B1
TURNAROUND TIME: 8 days.
TESTING METHODOLOGY: Polymerase chain reaction (PCR) and Shifted Termination Assay for detection of specific mutations. Mutations detected are V600E (GTGGCG), and V600G (GTG>GGG).
Collect: FFPE tumor specimen containing at least 30% tumor mass. 5 to 6 unstained slides with 3-4 um thick tissue sections. Must be accompanied by a pathology report and an H&E slide with the tumor regions identified.
- Transport: Specimen should be shipped at Room Temperature (No Saturday delivery
- Unacceptable Conditions: Stained slides.
Counseling and informed consent are recommended for genetic testing. A consent form
is available as a resource but not required.
Incidence: Found in 10-12% of all colorectal tumors.
Indications for Testing: BRAF mutations at codon 600 are present in 6-10% of colon cancers that are normal for the KRAS gene at codons 12 and 13. Tumors that have a BRAF mutation will not respond to anti-EGFR inhibitor drugs. KRAS and BRAF mutations are mutually exclusive.
Molecular Genetic Mechanism: The BRAF V600E mutation enhances the proliferation and metastasis of tumor cells.
Clinical Sensitivity: The tissue sample submitted for testing must contain at least 30% tumor. The assay will detect as low as a 5% population of mutant cells.
Analytical Sensitivity: 95%
Test Limitations: Mutations not listed in the methodology will not be detected. This test is only for somatic BRAF changes in cancer tissues. Rare diagnostic errors can occur due to primer / probe site mutations or rare polymorphisms.
INDICATIONS FOR USE:
- To assess the potential effectiveness of anti - EGFR therapies.
- Detection of the BRAF V600 mutations prior to expensive screening of the MMR genes.
- To determine whether a patient might be a candidate for BRAF kinase inhibitors.