What are BRCA1 and BRCA2?
Our bodies are made up of trillions of cells. Each cell contains DNA (deoxyribonucleic acid), which holds all the information needed for a cell to function. DNA is grouped into units called “genes” that are passed down from parents to their children. Genes act asinstructions for what we look like and how we develop, and can protect us against disease. Some changesor mutations in your genes can increase your risk of developing certain diseases, including cancer.Usually obtained via blood, samples of a person’s DNA can be analyzed to look for mutations in genes, like BRCA1 and BRCA2, that increase the chance of developing certain types of cancer. People with BRCA1 and BRCA2 mutations are more likely to develop cancer at a younger age and have high grade (aggressive) tumours.
People with BRCA1 and BRCA2 mutations are known to have an increased risk of the following types of cancer:1
- Ovarian, fallopian tube, and/or peritoneal (lining of the abdomen and organs)
5–10% & ~15% of breast cancer cases of ovarian cancer cases are associated with a mutation in a cancer predisposition gene.
In all ethnic populations, the most common forms of hereditary breast and ovarian cancer result from a mutation in either the BRCA1 or BRCA2 gene.
Germline mutations are mutations that occur in every cell in your body and have the possibility to be passed down to your children. Germline variants in BRCA1 or BRCA2 are inherited in an autosomal dominant manner. The offspring of an individual identified as having a BRCA1 or BRCA2 germline pathogenic variant have a 50% chance of inheriting the variant from that parent.
What is BRCA1 & BRCA2 Testing?
- Around 5 – 10 % of breast cancers result from a mutation in the BRCA1 and BRCA2 BRCA mutations increase the risk of developing breast and ovarian cancer, and patients with BRCA mutations tend to develop breast cancers at a younger age.
- Mutations in the BRCA genes can be sporadic, but they are often germline, meaning they are in all cells in your body and may be passed down to your Testing can be performed on a buccal swab sample which may indicate if there is a germline mutation in the BRCA gene. If the mutation is germline, family members can be tested to see if they have inherited the mutation, allowing earlier detection and prevention.
Why is it important to have genomic testing if I have a family history of cancer?
Testing for Inherited cancer syndromes informs clinical decision making and may assist in the prevention of adverse health outcomes. BRCA1 and BRCA2 are part of complexes involved in DNA repair using homologous recombination. Women with an abnormal BRCA1 or BRCA2 gene have up to an 80% risk of developing breast cancer by age 90 and up to 55% risk of developing ovarian cancer. In addition to breast cancer, mutations in the BRCA1/2 gene also increase the risk of ovarian, fallopian tube, pancreatic cancer, gastric cancer and prostate cancers.
If there is a family history of breast cancer, other members of your family can undergo genomics testing to see if they are a carrier of germline BRCA mutations. If they are identified as a carrier of the mutations, this can enable them to:
- Start cancer screening tests earlier
- Get screened for that type of cancer more often
- Get screening tests that are used only for people known to be at increased cancer risk
- Watch yourself closely for signs or symptoms of that kind of cancer
- Learn about options to help reduce the risk of certain types of cancer, such as drugs or surgery