If you have a family history of breast cancer, you may be wondering what your chances are of inheriting the condition.

Thanks to genetic research, this is a much easier question to answer. Mutations in two genes — BRCA1 and BRCA2 — have been identified as a primary genetic cause of breast cancer.

Not everyone who gets breast cancer inherits it through their family history. And not everyone with mutations in their BRCA1 or BRCA2 genes will develop breast cancer. But having these specific mutations does greatly increase your risk of developing breast cancer during your lifetime.

Let’s take a look at how these genetic mutations contribute to cancer, how you can find out if you have these mutations, and who’s a good candidate for genetic testing.

How do certain genes affect breast cancer?

Cancer is a health condition that can be caused by changes to your genes. Your genes carry instructions that tell the proteins in your cells how to behave.

When your genes cause proteins and cells to develop in abnormal ways, it can become cancer. This can happen because of a gene mutation.

It’s possible to be born with certain gene mutations. This is called an inherited mutation. Somewhere between 5 to 10 percent of breast cancers are currently thought to be hereditary. Your genes may also mutate later in life due to environmental or other factors.

A few specific mutations can play a role in developing breast cancer. Affected genes tend to be ones that control things like cell growth and the DNA in your reproductive organs and breast tissue.

BRCA genes and breast cancer

BRCA1 and BRCA2 genes typically make proteins that can repair your DNA when it gets damaged, particularly in your breasts and ovaries. When these genes are mutated, it can cause abnormal cell growth. These cells can then become cancerous.

About 50 out of every 100 women born with a BRCA gene mutation will develop breast cancer by the time they’re 70 years old, according to the Centers for Disease Control and Prevention (CDC). They also have an increased risk of developing other cancers, including:

  • melanoma
  • ovarian cancer
  • colon cancer
  • pancreatic cancer

People born with a penis and who have the BRCA2 mutation have an increased risk of developing male breast cancer.

Your risk for having BRCA1 or BRCA2 mutations may be higher if you have:

  • multiple family members who have been diagnosed with breast cancer
  • relatives who developed breast cancer before they were 50 years old
  • any family members who were diagnosed with ovarian cancer
  • any male relative who developed breast cancer
  • anyone in your family who developed both breast and ovarian cancer
  • someone in your family who has already been tested and found to carry a BRCA gene mutation

Other genes that can affect breast cancer

In addition to BRCA and BRCA2, there are other genes that can increase your risk of developing breast cancer if you inherit a mutation.

These genes include:

  • CDH1. Mutations in CDH1 put you at a higher risk of developing hereditary diffuse stomach cancer (gastric cancer). This mutation also increases your risk of lobular breast cancer.
  • PALB2. This gene partners with the BRCA gene in your body. People with mutations in the PALB2 gene are 9.47 times more likely to develop breast cancer than people who don’t have that mutation.
  • PTEN. This is a gene that regulates cell growth. A PTEN mutation can cause Cowden syndrome, a condition that increases your risk of developing benign and cancerous tumors, like those found in breast cancer.
  • TP53. Mutations in TP53 can lead to Li-Fraumeni syndrome, a condition that predisposes your body to several different types of cancer, including breast cancer and brain tumors.

Considerations for genetic testing

If you meet any of the criteria that increases your risk of having BRCA1 or BRCA2 mutations, as listed above, you may be considering genetic testing.

Genetic testing for BRCA1 or BRCA1 is usually a simple blood or saliva test. After a conversation and a prescription from a doctor, you’ll have a sample of your blood or saliva drawn and sent to a lab. The lab looks for the mutations, and the doctor will call you with the results.

You can also pay a direct-to-consumer company to do the test without a referral from your doctor. But these tests only test for BRCA1 and BRCA2 gene mutations. They can’t rule out any and all factors that could increase your risk of breast cancer.

If you’re curious about other genetic mutations that you may have, you’ll need to speak with a doctor about getting tested for those mutations, too.

The National Comprehensive Cancer Network offers criteria for who should consider getting a genetic test for BRCA1 and BRCA2 mutations, in addition to other gene mutations including those discussed above. Just know that insurance may not always cover genetic testing.

Currently, these tests aren’t seen as necessary or recommended for the general public. Genetic testing is only recommended if you have a family history of breast cancer or ovarian cancer.

Children under age 18 are not currently advised to get genetic testing for BRCA mutations. This is because there are no preventive measures that can be taken at that age and very little chance of children developing the types of cancers connected to these mutations.

The takeaway

BRCA1 and BRCA2 are known as the “breast cancer genes.” The genes themselves aren’t what increase your risk of breast cancer, because everyone has them. Mutations in the genes can produce an increased risk of breast cancer, ovarian cancer, and several other types of cancer.

For this reason, people with a family history of breast cancer are getting genetic testing to see if they have the mutation. Having the mutation doesn’t necessarily mean that you’ll develop breast cancer. Knowing your risk may make you feel more at ease, or it might make you anxious.

If you have a family history of breast cancer, speak with a doctor about the pros and cons about getting genetic testing for these mutations.

Frequently Asked Questions

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.
Types of cancer genes, Oncogenes are mutated genes that cause cells to grow out of control and can lead to cancer. Proto-oncogenes are normal genes that control cell growth but if they become mutated they can turn into oncogenes. Proto-oncogenes and oncogenes act like on/off switches.
A positive test result means that you have a mutation in one of the breast cancer genes, BRCA1 or BRCA2, and therefore a much higher risk of developing breast cancer or ovarian cancer compared with someone who doesn’t have the mutation. But a positive result doesn’t mean you’re certain to develop cancer.
Which Gene Mutation is Worse, BRCA1 or BRCA2? By age 70, women BRCA1 carriers have a slightly higher risk of developing breast cancer than BRCA2 carriers. Also, BRCA1 mutations are more often linked to triple negative breast cancer, which is more aggressive and harder to treat than other types of breast cancer.
Researchers have identified many personal and environmental factors that contribute to a person’s risk of developing breast cancer. These factors include sex, age, ethnic background, a history of previous breast cancer, certain changes in breast tissue, and hormonal and reproductive factors.
All men inherit a Y chromosome from their father, which means all traits that are only found on the Y chromosome come from dad, not mom. The Supporting Evidence: Y-linked traits follow a clear paternal lineage.
The cancers with the highest genetic contribution include breast, bowel, stomach and prostate cancers. Referral to a specialist cancer genetics service may be appropriate for people with a strong family history of cancer.
BRCA1 or BRCA2. Other cancers associated with the BRCA1 and BRCA2 genes include ovarian, pancreatic, prostate, and melanoma. Mutations in specific mismatch repair genes that cause Lynch syndrome. This is a hereditary disorder caused by mutations in the mismatch repair genes MLH1, MSH2, MSH6, PMS2, and EPCAM.
Prophylactic mastectomy can reduce the chances of developing breast cancer in women at high risk of the disease: For women with the BRCA1 or BRCA2 mutation, prophylactic mastectomy reduces the risk of developing breast cancer by 90 to 95 percent.
Genetic testing for BRCA1 or BRCA2 mutations is typically not recommended for children younger than 18, but can be considered when your children reach adulthood. Younger children might not be able to understand what your mutation means for you or for them.
You cannot inherit something from your parents that they don’t have. So if they do not have the gene change, you wouldn’t either. To better understand your risk for having a BRCA gene change, you should visit a genetic counselor.
Of those who died before 70 years, 58% were due to ovarian cancer, 38% to breast cancer, and 3% to other causes. In contrast, only 156 of 482 (32%) of BRCA2 carriers had died, with 131 (84%) dying before age 70. Of these deaths, 21% were due to ovarian cancer, 74% to breast cancer, and 4% to other causes (Table 2).
Genetically, you actually carry more of your mother’s genes than your father’s. That’s because of little organelles that live within your cells, the mitochondria, which you only receive from your mother.
Genetically, a person actually carries more of his/her mother’s genes than his/her father’s. The reason is little organelles that live within cells, the? mitochondria, which are only received from a mother.
Each parent will pass one copy of their eye color gene to their child. In this case, the mom will always pass B and the dad will always pass b. This means all of their kids will be Bb and have brown eyes. Each child will show the mom’s dominant trait.