Why Do Ashkenazi Jews Have a Higher Risk of Breast Cancer?

DNA strand
Photo courtesy of Caroline Davis2010 via Flickr.

Along with other controllable and uncontrollable risk factors, genetics can play a crucial role in determining breast cancer risk levels. When we talk about genetics in our breast health programs, people often ask if there are specific groups more prone to breast cancer. The answer is yes. Jewish people of Ashkenazi heritage have a 1 in 40 chance of carrying a BRCA gene mutation. And women with a BRCA gene mutation (popularly called the “breast cancer gene”) have a much higher chance of developing breast cancer, a 1 in 2 chance before the age of 70(1).

Ashkenazi Jews

Jewish people with Ashkenazi heritage are descendants of Jewish settlers that inhabited the Western Germany and Northern France area in the Middle Ages. Many of those settlers eventually migrated to Eastern Europe. For that reason, Ashkenazi Jews are often described as having “Eastern European” descent, as opposed to Iberian descent (Sephardi Jews) or Middle Eastern descent (Mizrahi Jews). Ashkenazi Jews make up an estimated 75-80% of the world’s Jewish population and they inhabit all corners of the world, with the largest population, 5-6 million, living in the United States(2).

Ashkenazi & The BRCA Gene

There are two types of BRCA genes, called BRCA1 and BRCA2 (BR for breast and CA for cancer). Everyone carries BRCA genes, which in their normal state repair damaged DNA and kill off abnormal cells before a tumor can form. Having a harmful mutation on a BRCA gene is what increases our risk of developing various types of cancer, including breast cancer. BRCA genes are hereditary, meaning they are passed down from a parent to a child.

Because Jewish people often inter-marry with one another (or have a high rate of “endogamy”) and are such a large population, they make an ideal group for geneticists to study. Scientists have extensively researched Ashkenazi Jews and have found a higher rate of mutated BRCA genes, putting them at an increased risk for pancreatic, prostate, ovarian and breast cancer. In fact, 1.5% of all living Ashkenazi Jews are estimated to have a mutated BRCA1 gene and 1%  have a mutated BRCA2 gene(3).

What You Can Do About Breast Cancer

Knowledge is power. A great starting point is to talk to your family. Determine your Jewish heritage if you are unsure and find out if any of your family members have been diagnosed with cancer, especially breast cancer. Think ahead of time about how to talk to your family about genetic testing for BRCA and breast cancer. While having a mutated BRCA gene increases your risk of a cancer diagnosis, that risk is influenced by the cancers that are in your family history. For breast cancer, know the cancer history of your first-degree relatives (your mother, sisters, and daughters) and second-degree relatives (aunts, grandmothers and nieces) on both sides of your family.   

While at-home test kits do exist, Jews of Ashkenazi heritage will benefit from professional genetic counseling that includes BRCA testing and pre- and post-testing guidance. There are definitely misguided ways to do genetic testing. Professional genetic counselors can help interpret results and develop prevention plans customized to your genetic make-up and risk levels.

The good news is that having a mutated BRCA gene does not guarantee being diagnosed. One of the best and easiest things we can do to decrease our risk of breast cancer, regardless of whether or not we carry mutated BRCA genes, is to stay at a normal weight, exercise, reduce fat intake, and cut out smoking and alcohol. While we cannot control our genetic makeup, we can modify our lifestyle choices to lower our risk.

Sources

  1. Jewish Women and BRCA Gene Mutations, Centers For Disease Control and Prevention (CDC)
  2. Ashkenazi Jews, Wikipedia
  3. Specific to Individuals of Ashkenazi Jewish Ancestry, Johns Hopkins University, Pathology

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