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The information on this page was reviewed and approved by
Maurie Markman, MD, President, Medicine & Science at CTCA.

This page was updated on June 10, 2021.

BRCA1 and BRCA2

In 2021, about 281,550 women in America will learn they have invasive breast cancer, according to the American Cancer Society (ACS). Approximately 5 to 10 percent of these cases may be hereditary, resulting from abnormal gene mutations, the ACS adds.

Every cell in the body contains genes. Made up of short strands of DNA, these genes provide blueprints—they tell the cells how to make what’s needed to function properly and to stay that way. Everyone gets two copies of his or her genes, one from each parent.

To help keep track of the many genes in the body, scientists have given each a unique name. Because the names are long, they’re often abbreviated.

What are BRCA1 and BRCA2?

The two genes most responsible for breast cancers have been labeled BRCA1 and BRCA2, with “BRCA” standing for “breast cancer.” In most people, these genes function normally, helping stave off tumors. However, some people have mutated or damaged BRCA1 and BRCA2 genes. If you have mutations within these genes, they won’t function as well as they should.

Mutations to the BRCA1 and BRCA2 genes are inherited, either from a person's mother or father (or both), and these are linked to an increased risk for several types of cancer—most notably, female breast and ovarian cancers.

  • If a parent has the variant, the patient has a 50 percent chance of inheriting it, according to the National Cancer Institute (NCI).
  • Women with a BRCA1 gene mutation have a 55 to 72 percent chance of developing breast cancer by the time they are 70 to 80 years old, the NCI says. The chance with an abnormal BRCA2 gene is 45 to 69 percent. By contrast, an average-risk woman has about a 13 percent chance of developing breast cancer sometime in her lifetime.
  • About 30 out of 100 women with a BRCA1 or BRCA2 mutation are likely to develop ovarian cancer by the time they’re 70, according to the U.S. Centers for Disease Control and Prevention (CDC). That’s much higher than the rate for the U.S. population in general, which sees fewer than one out of 100 women develop ovarian cancer.
  • Men may also inherit these gene mutations. Like women, men who inherit them face an increased risk of breast cancer. These men are also at greater risk of developing other cancers, such as prostate cancer.

Does ethnicity affect risk for harmful BRCA1 and BRCA2 mutations?

Anyone may inherit these gene mutations, but in the United States, they are found most commonly in those of Ashkenazi Jewish ancestry. The NCI says about 2 percent of Ashkenazi Jews carry the harmful variant in one of these two genes. Black women in the United States also tend to have BRCA1 variants unique to their racial group.

Who should be tested for gene mutations?

The U.S. Preventive Services Task Force recommends that women with a family history of breast, ovarian, fallopian tube or peritoneal cancer undergo testing. Other factors that may increase the risk of these mutations include:

  • A personal history of breast or ovarian cancer
  • A breast cancer diagnosis before age 50
  • Ashkenazi Jewish ethnicity

Genetic tests require samples of a patient’s blood or saliva. A laboratory analyzes the samples in search of any mutations. Most tests are for the BRCA1 and BRCA2 genes, but if there’s a reason to think the patient may have other gene changes that could be significant, testing may look for them as well.

Genetic testing may be expensive. If you’re interested, ask a genetic counselor to verify whether your health insurance covers the cost. If you don’t have insurance but meet specific financial and medical criteria, you may have access to free genetic testing.

At-home genetic tests are also available. However, the U.S. Food and Drug Administration warns that these direct-to-consumer tests are not as regulated and not always reliable. If you use these tests, speak with your doctor about your results.

Other genes to know

BRCA1 and BRCA2 aren’t the only genes that may lead to inherited breast cancers. However, the other gene mutations are less common and don’t increase the risk of breast cancer as much as the BRCA genes do. These mutations include those below.

ATM: When healthy, this gene helps repair damaged DNA. If the damage can’t be fixed and the gene isn’t healthy, it might kill the damaged cell. Inheriting one abnormal copy of this gene has been associated with an increased rate of breast cancer in some families.

CDH1: This gene mutation puts women at greater risk of invasive lobular breast cancer. Lobules are the breast’s milk-producing glands. Invasive lobular cancer may spread to other parts of the body.

CHEK2: This is yet another gene that, when normal, helps with DNA repair. When mutated, it increases the risk of breast cancer because it can’t do its job.

PALB2: This gene provides instructions for making a protein that interacts with the protein the BRCA2 gene makes. If it’s mutated, it may result in a higher risk of breast cancer.

PTEN: This gene controls the rate at which cells divide, helping to prevent abnormal growth. Mutations in this gene put people at higher risk for not only noncancerous and cancerous tumors of the breast, but also of the digestive tract, thyroid, uterus and ovaries.

STK11: People with this gene mutation are at higher risk for a number of types of cancers, including breast cancer.

TP53: This gene recognizes when a cell’s DNA has been damaged and stops it from causing further damage. However, if it’s mutated, the damaged DNA doesn’t get repaired, and damaged cells may grow and lead to cancer. This particular mutation is not often a cause of breast cancer, though.