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Hereditary Breast and Ovarian Cancer (HBOC) syndrome is a condition that can be passed down from parent to child. People with this condition have a much higher chance of developing certain cancers like breast, ovarian, and prostate cancers because of DNA differences in their BRCA1 or BRCA2 gene. It is most common in people of Ashkenazi Jewish descent, though it can be found in many other populations as well.

More about HBOC syndrome

People with HBOC syndrome have a higher chance of developing certain cancers because of DNA differences in their BRCA1 or BRCA2 genes. For example, women* with this condition can have up to a 79% chance of developing breast cancer by age 80. And they can have up to a 53% chance of developing ovarian cancer by the same age.

Men* are just as likely as women to inherit this condition and pass it down to their children. Men with HBOC also have a greater chance of getting prostate cancer, breast cancer, and pancreatic cancer, among others. For instance, although many are unaware, males can also develop breast cancer. While the risk is small, more than 2,000 males a year develop breast cancer in the U.S.

Around 1 in 200 people in the U.S. has a DNA difference in their BRCA1 or BRCA2 gene linked to HBOC. The condition is more common in some populations. For instance, about 1 in 40 people of Ashkenazi Jewish descent has it.

Why is it important to know about HBOC syndrome?

There are things that people with HBOC syndrome can do to lower their chances of developing cancer at an earlier age in addition to maintaining a healthy weight, staying active, and eating a healthy diet as recommended by the American Cancer Society.

Women with HBOC, for instance, can lower their risk for breast cancer by starting cancer screenings like mammograms and breast MRIs at an earlier age.  Some women may be recommended to take a medication to lower their risk.

Others may discuss surgical options with their doctors, such as a mastectomy or the removal of the ovaries and fallopian tubes. This last one may be especially important as there is no simple and effective screen available for ovarian cancer.

Angelina Jolie famously had genetic testing in 2013 and found out she had a DNA difference in her BRCA1 gene. She wrote an article in The New York Times about choosing to have both breasts removed and in 2015 had her ovaries removed.

These surgeries are often very personal decisions and involve many medical and personal factors, such as family history and future plans for family. Remember that having HBOC syndrome doesn’t mean you have cancer, just that your chances of having it are higher.

How is HBOC passed down?

People who have HBOC syndrome most likely got it from one of their parents. This means that at least one of their parents probably has HBOC too.

Each child of someone with HBOC has a 50% chance of having HBOC. Any full brothers and sisters have a 50% chance of having HBOC as well.

This is especially important information for the close biological female relatives of someone with HBOC syndrome such as their mother, sisters, or daughters. That’s because some of the DNA differences that can cause HBOC are a lot more likely to cause cancer—particularly breast and ovarian cancer—in females than in males. Keep in mind that the American Medical Association does not recommend genetic testing for HBOC for people under the age of 18.

Here is how the inheritance works in most cases:  A person has two copies of most of their genes, one from each parent. To have HBOC, they would only need to inherit an HBOC DNA difference from one of their parents. This type of inheritance is called autosomal dominant inheritance.

Is there genetic testing for breast cancer?

While a genetic test for HBOC syndrome cannot tell someone if they currently have cancer, it can tell them they have a higher chance than typical of developing certain cancers.  Breast cancer is the most common cancer females with HBOC develop.

What does the test offered through AncestryHealth® look at?

The test offered through AncestryHealth® looks for specific DNA differences in two genes, BRCA1 and BRCA2. These genes may be referred to by some as “breast cancer genes.” But it’s more accurate to say that they are genes that scientific research has found are linked to a higher chance of developing breast cancer because differences in these genes can cause HBOC syndrome.

While other genes can impact breast and ovarian cancer risks, BRCA1 and BRCA2 have the highest impact and are the most common in the general population. AncestryHealth®, powered by next-generation sequencing technology, can detect about 80% of the DNA differences linked to the most common form of inherited breast cancer.

What do BRCA genes do and how are they related to cancer?

Cancer happens when mistakes build up in one’s DNA over time. Because cells have ways to fix mistakes, this is usually a slow buildup of damage over time. This is why cancer usually happens later in life.

The genes involved in HBOC syndrome, BRCA1 and BRCA2, are a part of how cells fix their DNA and how they keep tumors from growing. DNA differences—also called mutations or variants—in these genes can cause the repair system to not work as well. The end result is a faster buildup of mistakes which means a higher risk of cancer earlier in life.


*Assigned sex at birth


AncestryHealth® includes laboratory tests developed and performed by an independent CLIA-certified laboratory partner, and with oversight from an independent clinician network of board-certified physicians and genetic counselors. The test results are not diagnostic and do not determine your overall chance of developing a disease or health condition. The tests are not cleared or approved by the U.S. Food and Drug Administration. You should consult a healthcare provider before taking any action based on AncestryHealth® reports, including before making any treatment, dietary, or lifestyle changes. AncestryHealth® is not currently available in New York, New Jersey or Rhode Island.


Selected references

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