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What are my chances of having an altered BRCA gene?

Main points

  • About 3% (3 in 100) breast cancers are caused by altered BRCA genes.
  • Having a strong family history of breast cancer does not mean you will definitely have an altered BRCA gene. Even when an altered BRCA gene is not found, families with a strong family history of breast cancer may still have a higher chance of breast cancer.
  • Having had cancer yourself and a strong family history of breast cancer (particularly at a young age) makes it more likely that you will have an altered BRCA gene.
How likely is it that I have an altered BRCA gene?
  • Around 3% of breast cancers are caused by altered BRCA genes. This means that about 3 out of 100 people with breast cancer will have an altered BRCA gene. Even if you have a strong family history of breast cancer, this does not mean you definitely have an altered gene. A strong family history can also happen just by chance or because of genetics which are not linked to known altered genes. Breast cancer can also happen just by chance.
    What increases my chances of having an altered BRCA gene?
    • Breast cancer diagnosed under the age of 50
    • Having breast cancer in both breasts
    • Relatives who have had breast cancer at a young age (under 50)
    • Men in the family who have had breast cancer
    • Family or personal history of ovarian cancer
    • Diagnosis of triple negative breast cancer
    • The chances of having an altered gene are higher in some ethnic groups, for example Ashkenazi Jew and Polish

    You may wish to talk to your healthcare professional about your personal chance of having an altered gene.

Click here for how genes are passed down.

altered gene

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Who can have BRCA testing?
  • People with a higher than usual chance of having an altered gene can currently be tested on the NHS.
  • A genetics or breast clinic can give you an idea about your personal chance of having an altered BRCA gene by looking at your age, your family history and your type of breast cancer.
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