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BRCA Mutations and why they matter

Sometimes, changes or “mutations” occur that prevent genes from doing their job properly. Certain mutations in the BRCA genes make cells more likely to divide and change rapidly, which can lead to cancer.

​All people have BRCA1 and BRCA2 genes, but only some women have mutations in those genes. About 1 in every 500 women in the United States has a mutation in either her BRCA1 or BRCA2 gene. If either your mother or your father has a BRCA1 or BRCA2 gene mutation, you have a 50% chance of having the same gene mutation.

Some groups are at a higher risk for a BRCA gene mutation than others, including women with Ashkenazi Jewish heritage.

What are BRCA1 and BRCA2?

BRCA1 (BReast CAncer gene 1) and BRCA2 (BReast CAncer gene 2) are genes that produce proteins that help repair damaged DNA. Everyone has two copies of each of these genes - one copy inherited from each parent. 

BRCA1 and BRCA2 are sometimes called tumor suppressor genes because when they have certain changes, called harmful (or pathogenic) variants (or mutations), cancer can develop.

People who inherit harmful variants in one of these genes have increased risks of several cancers—most notably breast and ovarian cancer, but also several additional types of cancer. People who have inherited a harmful variant in BRCA1 and BRCA2 also tend to develop cancer at younger ages than people who do not have such a variant. 

A harmful variant in BRCA1 or BRCA2 can be inherited from either parent. Each child of a parent who carries any mutation in one of these genes has a 50% chance (or 1 in 2 chance) of inheriting the mutation. Inherited mutations—also called germline mutations or variants—are present from birth in all cells in the body. 

Even if someone has inherited a harmful variant in BRCA1 or BRCA2 from one parent, they would have inherited a normal copy of that gene from the other parent (that’s because in most cases, embryos with a harmful variant from each parent cannot develop). But the normal copy can be lost or change in some cells in the body during that person’s lifetime. Such a change is called a somatic alteration. Cells that don’t have any functioning BRCA1 or BRCA2 proteins can grow out of control and become cancer.

​Why BRCA Gene Mutations Matter

Not every person who has a BRCA1 or BRCA2 gene mutation will get breast or ovarian cancer, but having a gene mutation puts you at an increased risk for these cancers.

About 50 out of 100 women with a BRCA1 or BRCA2 gene mutation will get breast cancer by the time they turn 70 years old, compared to only 7 out of 100 women in the general United States population.

About 30 out of 100 women with a BRCA1 or BRCA2 gene mutation will get ovarian cancer by the time they turn 70 years old, compared to fewer than 1 out of 100 women in the general U.S. population.

If you have a family history of breast cancer or inherited changes in your BRCA1 and BRCA2 genes, you may have a higher cancer risk. Talk to your doctor about these ways of reducing your risk.

Surgery to reduce your risk of cancer—

  • Prophylactic (preventive) mastectomy (removal of breast tissue).
  • Prophylactic (preventive) salpingo-oophorectomy (removal of the ovaries and fallopian tubes).
  • Antiestrogens or other medicines that block or decrease estrogen in your body.

It is important that you know your family history and talk to your doctor about screening and other ways you can lower your risk.

SOURCE: BRCA Gene Mutations | Bring Your Brave | CDC

SOURCE: BRCA Gene Mutations: Cancer Risk and Genetic Testing Fact Sheet - NCI