BRCA 101


ON THIS PAGE:

What is a BRCA Mutation?

Is a BRCA mutation hereditary? (How did I get a BRCA mutation?)

If I have a BRCA mutation, will I pass it on to my children?

Can a BRCA mutation skip a generation?

If I test Negative for the BRCA mutation does that mean I will NOT get cancer?

If I test Positive for a BRCA mutation, does that mean I WILL get cancer?

What are my chances for developing cancer with a BRCA gene mutation?

There is a lot of cancer in my family. Do I have the BRCA mutation?


What is a BRCA mutation?

A BRCA mutation is a change in either of two genes - BRCA1 or BRCA2 (Breast Cancer 1 and 2 genes) - that prevents that gene from working properly. Both BRCA1 and BRCA2 are tumor suppressor genes. This means that when the genes are working properly they control the way cells grow in certain tissues of the body. A mutation in either gene is associated with an increased chance of developing breast cancer, ovarian cancer, and some other specific types of cancer. All of us carry two copies of the BRCA 1 and BRCA2 genes. Mutations in these genes increase the risk for developing cancer.

However, cancer is caused by a combination of genetic and environmental factors. Gene mutations only explain a subset of all cancers. You may still be at increased risk depending upon the cause of the cancer in your family. Only about 5-10% of women with breast cancer are BRCA positive, therefore not everyone needs to be tested for BRCA.

For more information on the BRCA Mutation, please visit:

BRCA1
As part of the National Institute of Health Genetics Home Reference Guide

BRCA2
As part of the National Institute of Health Genetics Home Reference Guide

Cancer Risk and Abnormal Breast Cancer Genes
by Breast Cancer.org

Genetic Testing for Breast and Ovarian Cancer Risk: It’s Your Choice
by National Cancer Institute

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Is a BRCA mutation hereditary? (How did I get a BRCA mutation?)

Yes, a BRCA mutation can be passed to you from your mother or father. BRCA mutations are inherited in a dominant fashion, which means one copy of an altered BRCA1 or BRCA2 gene in each cell is sufficient to increase your chance of developing certain cancers. It is important to remember that not everyone who inherits mutations in these genes will develop.

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If I have a BRCA mutation, will I pass it on to my children?

When a person with a BRCA mutation has children, each child has a 50/50 chance (1 in 2) of inheriting the BRCA mutation and a 50/50 chance of inheriting the working BRCA gene copy. Those children who inherit the BRCA mutation have an increased chance of developing cancer and can also pass the gene on to their children. Those who inherit their parents’ working BRCA gene copy cannot pass the mutation on to their children. In cases where a BRCA mutation is NOT passed onto a child, family history of cancer is still prevalent and it is important to note that they are still at risk of developing cancer, just not due to a BRCA mutation!

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Can a BRCA mutation “skip” a generation?

Although having a BRCA mutation increases the chance of developing cancer, some people with a mutation never get the disease. Therefore, sometimes it looks like cancer has “skipped” a generation when you look at a family history. This may be especially true when the gene mutation is passed through a male who has a lower risk of cancer. For instance, you may see a family history where a woman and her paternal grandmother (her father’s mother) both have breast cancer and a BRCA mutation, but the woman’s father does not have cancer. The BRCA mutation does not skip generations. As in this example, even though it appears to have skipped a generation - the father has no cancer - the mutation is still present in the father (the father is a carrier).

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If I test Negative for a BRCA mutation does that mean I will NOT get cancer?

NO!! There are MANY factors that contribute to developing cancer. In fact, only about 5-10% of women with breast cancer have tested positive for a BRCA mutation. Cancer is caused by a combination of genetic and environmental factors. Gene mutations only explain a subset of all cancers. You may still be at increased risk depending upon the cause of the cancer in your family.

To learn more about your risk for developing cancer, with or without the BRCA mutation, please visit:

Cancer Risk: Understanding the Puzzle

Breast Cancer Risk Assessment Tool
by the National Cancer Institute

The Breast Cancer page
by National Cancer Institute


For more information on negative BRCA mutation results and developing cancer, please visit:

BRCA Mutations Don't Spot All High-Risk Women
by HealthDay

Genetic Testing for BRCA1 and BRCA2
by National Cancer Institute

Spectrum of Mutations in BRCA1, BRCA2, CHEK2, and TP53 in Families at High Risk of Breast Cancer
by the Journal of the American Medical Association

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If I test Positive for a BRCA mutation, does that mean I WILL get cancer?

NO! As Dr. Narod says in the beginning of In the Family, “Look, it’d be a lot easier if we could say ‘you’re gonna get it, you’re not.” Testing positive for a BRCA mutation only tells us that you have an increased RISK of developing cancer. A test result will not show if you will develop cancer - or when. Not all women who inherit a BRCA mutation will develop breast or ovarian cancer.

For more information on your risk of developing cancer with a BRCA mutation, please visit:

National Cancer Institute Fact Sheet, BRCA

Cancer Risk: Understanding the Puzzle

Breast Cancer Risk Assessment Tool
by the National Cancer Institute

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What are my chances for developing cancer with a BRCA gene mutation?

According to estimates, about 36% – 85% of women with a BRCA gene mutation will develop breast cancer. Women with working copies of BRCA genes are about 13% likely to develop breast cancer over their lifetime. In other words, women with an altered BRCA1 or BRCA2 gene are 3 to 7 times more likely to develop breast cancer than women without a BRCA mutation.

Having a BRCA mutation increases your lifetime risk of developing ovarian cancer from an estimated 2% (general population) to between 16% - 60%. Note that these figures are estimated ranges that may change with more research.

A woman's lifetime chance of developing breast and/or ovarian cancer is greatly increased if she tests positive for a BRCA mutation. If you have a BRCA mutation, you also have an increased risk of developing these cancers at a young age (before menopause), and may have an increased chance of developing colon cancer.

Men with a BRCA gene mutation have an increased risk of developing breast cancer, prostate cancer and skin cancer (melanoma). Furthermore, these cancers are more likely to develop at a younger age in men with a BRCA mutation. These are very low, if even real, risks. Please make sure to speak with your primary care provider about your individual risk if you are a man with a BRCA mutation.

Additionally, in some people, BRCA2 gene mutations have been associated with an increased risk of lymphoma, melanoma, and cancers of the pancreas, gallbladder, bile duct, and stomach.

For more information on lifetime risk of developing cancer with a BRCA mutation, please visit:

BRCA Fact Sheet
by the National Cancer Institute

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There is a lot of cancer in my family. Do I have a BRCA mutation?

Let’s face it: cancer is common. Almost everybody has at least one relative with the disease. Most cancers happen by chance or due to environmental exposures. However, some people have an increased chance to develop certain types of cancer, such as breast or ovarian cancer, because of a genetic mutation. About 5-10% of all breast cancer cases and 10% of ovarian cases are due to a BRCA mutation.

The likelihood that breast and/or ovarian cancer is associated with BRCA1 or BRCA2 is highest in families with a history of multiple cases of breast cancer, cases of both breast and ovarian cancer, cancer at early/young ages, one or more family members with two primary cancers (original tumors at different sites), or an Ashkenazi (Eastern European) Jewish background. However, not every woman in such families has a mutation in BRCA1 or BRCA2, and not every cancer in such families is linked to mutations in these genes.


Signs that there may be a BRCA mutation in you or your family include:

  • You or a family member have been diagnosed with breast cancer at an earlier age than usual (before age 50)
  • You or a family member have developed two or more separate cancers (for example, a woman who develops breast cancer and then later ovarian cancer)
  • Two or more of your relatives in the same blood line have been diagnosed with breast or ovarian cancer
  • There is a known BRCA mutation in your family. (Thus, there IS a BRCA mutation in your family, and that means you MAY have a BRCA mutation)
  • There is a family history of breast or ovarian cancer and your family is of Ashkenazi Jewish descent

To determine whether genetic testing for a BRCA mutation is right for you, make an appointment to speak with a genetic counselor and discuss your family health history.

For more information on BRCA Mutation and history of Cancer in families, please visit:

National Cancer Institute Fact Sheet, BRCA

Signs of Hereditary Breast and Ovarian Cancer (HBOC)
by FORCE

BRCA Risk Calculator
by Myriad Genetics

Risk Mutation Prevalence Tables
by Myriad Genetics

Genetic Risk Assessment and BRCA Mutation Testing for Breast and Ovarian Cancer Susceptibility
by U.S. Preventive Services Task Force

The Risk of Cancer Associated with Specific Mutations of BRCA1 and BRCA2 among Ashkenazi Jews
by The New England Journal of Medicine

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