BRAF V600

OVERVIEW

BRAF is a proto-oncogene that codes a protein kinase called B-Raf or v-Raf murine sarcoma viral oncogene homolog B. The protein is an integral component of the MAP kinase pathway and is involved in cell proliferation, differentiation, survival, and apoptosis1. More than thirty BRAF variants have been identified and reported in human neoplasms, with changes in the V600 codon being the most common (>97% of BRAF mutations)3. Activating variants in the BRAF gene leads to uncontrolled cell growth and proliferation.

Cancer/DiseasePrevalence of BRAF Mutation1-5Percentage of BRAF Mutations in V6001-5
Melanoma40-60%85%
Colorectal Cancer7-10%90%
Anaplastic Thyroid Cancer19-45%51%
Hairy Cell Leukemia70-100%95%
Langerhans Cell Histiocytosis57%>90%
Erdheim-Chester Disease50-60%>90%

INDICATIONS

Our BRAF V600 assay is offered for a variety of different disease types:

REFERRAL

Any BC licensed Medical Oncologist, Hematologist, or Pathologist.

TEST REQUIREMENTS

  1. Completed CGL Solid Tumour Testing requisition form
  2. One of the following specimens (see Specimens Guidelines page, DNA molecular test type:
    • Formalin-Fixed Paraffin-Embedded Tumour Tissue
    • Bone marrow aspirate in EDTA tube (for hematologic disease)
    • Peripheral blood EDTA (for hematologic disease)

TRANSPORT

See our Specimens Guidelines page.

METHOD

Tumour tissue is isolated from the specimen by macrodissection, followed by extraction of genomic DNA. Analysis of BRAF codon 600 is performed by quantitative PCR using LNA bearing allele specific PCR amplification primers. This assay can reliably detect BRAF V600E, V600K, and V600D variants; however, the specific change cannot be distinguished. The limit of reliable detection of this assay is 1% (with 100ng of input gDNA).

Note: The current assay is not designed to detect the BRAF V600R variant, however this may be identified under certain test and specimen conditions. Samples suspected of carrying a V600R variant may receive confirmatory testing using Sanger sequencing (limit of reliable detection of 15%).

CLINICAL UTILITY

BRAF V600 variants are useful as predictive, prognostic, or diagnostic biomarkers in a variety of tumour types (see individual pages, linked above). 

TURN-AROUND TIME

Results are reported within ten working days from receipt of specimen and completed requisition form. Failed analyses may be repeated at the discretion of the Laboratory Geneticist or Director, should sufficient sample be available for repeat analysis.

REFERENCES

  1. Luu, L-J. et al. BRAF Mutation and Its Importance in Colorectal Cancer, Advances in the Molecular Understanding of Colorectal Cancer. 2019.
  2. Spathis, A. et al. BRAF Mutation Status in Primary, Recurrent, and Metastatic Malignant Melanoma and Its Relation to Histopathological Parameters. Dermatology Practical & Conceptual. 2019; 9(1): 54-62.
  3. Cheng, L. et al. Molecular testing for BRAF mutations to inform melanoma treatment decisions: a move toward precision medicine. Mod Pathol. 2018; 31(1): 24-38.
  4. Xie, H. et al. BRAF mutation in papillary thyroid- carcinoma (PTC) and its association with clinicopathological features and systemic inflammation response index (SIRI). American Journal of Translational Research. 2018; 10(8): 2726-2736.
  5. Kebebew, E. et al. The Prevalence and Prognostic Value of BRAF Mutation in Thyroid Cancer. Annals of Surgery. 2007; 246(3): 466-471.
  6. Troussard, X. et al. Hairy cell leukemia 2018: Update on diagnosis, risk-stratification, and treatment. American Journal of Hematology. 2017; 92(12): 1382-1390.
  7. Zhang, L. et al. Genetic studies yield clues to the pathogenesis of Langerhans cell histiocytosis. European Respiratory Journal. 2016; 47: 1629-1631.