The Difference between BRCA1 and BRCA2

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Certain inherited genetic mutations increase the risk of breast cancer. Of these, the most common are mutations to the BRCA1 and BRCA2 genes. Here we’ll explore the difference between BRCA1 and BRCA2, and why the mutations to these genes increase the risk of developing cancer.

 

What are BRCA1 and BRCA2?

BRCA stands for breast cancer susceptibility gene. While most women have a one-in-eight chance of developing breast cancer in their lifetime, women with mutated BRCA1 or BRCA2 genes may have as much as a four in-five chance and are more likely to develop cancer at an early age.

Everyone possesses BRCA 1 and 2 genes, which help regulate cellular growth and suppress the development of tumors. Mutations to either gene can result in uncontrolled cell growth which can be cancerous.

The BRCA genes are hereditary meaning that you receive a copy of each gene from each parent. If both genes are mutated, your risk of cancer increases. If you receive a normal copy of the gene from one parent and a mutated copy from the other, the normal gene controls cell growth. Should the normal gene mutate, however, your risk of cancer increases at the site of the mutation. For women, this is usually in the breast or ovaries, although BRCA mutations can cause cancer in other parts of the body.

 

What’s the Difference between BRCA1 and BRCA2?

While these two genes perform similar functions, there is a difference between BRCA1 and BRCA2. The two genes are found on different chromosomes: BRCA1 is located on chromosome 17 and BRCA2 is found on chromosome 13.

Another difference between BRCA1 and BRCA2 can be found in how each mutation affects your risk of cancers other than breast and ovarian cancers:

  • BRCA1 mutations increase the risk of breast, ovarian, pancreatic, cervical, uterine, and colon cancers. BRCA1 mutations are also associated with an increased risk of triple-negative breast cancer, an aggressive and frequently difficult to treat cancer.
  • BRCA2 mutations increase the risk of breast, ovarian, pancreatic, gallbladder, bile duct, and melanoma cancers.

While BRCA mutations are most often associated with a woman’s risk of breast or ovarian cancer, men can also be affected. Men with BRCA1 and BRCA2 mutations have a higher risk of developing breast, testicular, prostate, and pancreatic cancers.

 

Who Should be Tested for BRCA Mutations?

You should consider genetic testing for BRCA1 and BRCA2 mutations if any of the following factors are present on either side of your family history:

  • Anyone in the family with Ovarian Cancer
  • two or more first-degree relatives (mothers, sisters, daughters) with a history of breast cancer
  • any first-degree relative diagnosed with breast cancer at or before age fifty,
  • three or more first and second-degree (grandmothers, aunts) relatives who develop breast cancer
  • any first-degree relative with a history of cancer in both breasts
  • any first or second-degree relative with a history of both breast and ovarian cancer
  • breast cancer in any male relative

Remember, a positive result for either BRCA1 or BRCA2 mutations does not mean you will inevitably develop cancer, only that you have a higher than normal risk and should consider discussing risk-reduction strategies with your oncologist,  genetic counselor, or other health provider.

 

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