Genetics is a word that is used frequently in the conversation around modern health care, but we don’t always appreciate its influence. This highly complex science can have wide ranging implications for our health and wellness.
The American Society of Human Genetics explains the role of genes found in every cell of the body this way: “A gene is made of DNA (deoxyribonucleic acid) and is basically a type of genetic instruction. Those instructions can be used for making molecules and controlling the chemical reaction of life. Genes can also be passed from parent to offspring; this is inheritance.” And it’s this inheritance aspect that can play a role in whether you’ll develop certain types of cancer at some point in your life.
[See: 16 Health Screenings All Women Need.]
The American Cancer Society reports that “some types of cancer run in certain families, but most cancers are not clearly linked to the genes we inherit from our parents.” And all cancers begin with a gene mutating, which results in abnormal cell growth that proliferates and becomes cancer.
Breast cancer is one of those cancers with a clearly defined genetic component. The most widely known genetic factor that can lead to breast cancer is a mutation on the BRCA1 or BRCA2 gene, which can also cause ovarian cancer. Everyone has these genes, but only some people have a mutation that can predispose them to certain types of cancer. According to the Centers for Disease Control and Prevention, “about 1 in every 500 women in the United States has a mutation in either her BRCA1 or BRCA2 gene. If either your mother or your father has a BRCA1 or BRCA2 gene mutation, you have a 50 percent chance of having the same gene mutation.”
Although having a gene mutation does not mean you’ll definitely develop cancer during your lifetime, it does increase the chances that you might. The CDC reports that about 50 percent of women with a BRCA1 or BRCA2 gene mutation will develop breast cancer by the time they turn 70. Among the general population, the rate is about 8 percent, so it’s a significantly higher risk.
Virtually anyone can have a BRCA1 or BRCA2 gene mutation, but in certain populations, it’s more common. One such population is Ashkenazi Jews. The CDC reports that 1 in 40 Ashkenazi Jewish women has a BRCA gene mutation.
The term Ashkenazi Jew refers to an ethnic group of diaspora Jews who lived in Central and Eastern Europe in the first millennium. They lived in distinct communities and did not blend much into the rest of the population, which means certain genetic characteristics have been preserved down the generations. In genetics, this is referred to as the “Founder Effect,” says Leigha Senter, associate professor, clinical at the Ohio State University and a licensed genetics counselor. “While there are Ashkenazi Jewish people all over the world, centuries ago they were geographically traced back to a few founders of the population,” who lived in closed communities mostly in Europe. She says these founders had the genetic mutation and passed it on to the next generation, and so on. “These mutations flourished when the population was geographically isolated, and today, approximately 1 in 40 individuals [of Ashkenazi background] has one of these founder mutations in BRCA1 or BRCA2 genes as compared to 1 in 800 individuals of non-Ashkenazi Jewish background.”
[See: 5 Rare Diseases You’ve Never Heard of (Until Now).]
According to a 2014 study conducted at Columbia University and published in the journal Nature Communications, today’s worldwide population of roughly 10 million Ashkenazi Jews is descended from a core group of about 350 people 25 to 32 generations ago, or roughly 600 to 800 years back. This small original group is referred to as a population “bottleneck” and the subsequent generations passed on their same genes, putting them at higher risk for certain genetic disorders. The genetic variations this group carried not only predisposes modern members of the ethnic group to breast and ovarian cancer, but 17 other diseases including Tay-Sachs disease, the study found.
It’s been estimated that anywhere from 75 percent to 90 percent of American Jews are of Ashkenazi descent. Therefore, if you’re Jewish or of Jewish descent, you might want to consider getting genetic testing and counseling to find out what your risks are for breast and ovarian cancer and other hereditary diseases. Senter says she works with many families and individuals who want to know what their genetic make-up may hold for their future health, and they typically start by taking a three-generation family health history. If you’ve had several family members with breast, ovarian or hereditary colon cancer, it might be worth doing further testing to find out your actual risk.
Senter also points out that mutations on the BRCA genes are not the only ones that can cause cancer, but they are the most common. A full genetic workup would likely reveal any other risk factors you might have based on your ancestry.
Senter says genetic counselors “can be involved at multiple points, before and after,” and often facilitate the testing. A counselor may be involved on the front end when a person or family is deciding to undergo genetic testing and determining which tests would be the most appropriate.
Genetic testing can be conducted via a simple blood test, but Senter says some labs use a saliva sample. Although the test itself is relatively noninvasive, the results can lead to difficult ethical and health questions. Genetic counselors help patients navigate these issues, such as whether to have children, terminate a pregnancy or undergo prophylactic treatments like a bilateral mastectomy (removal of both breasts) or oophorectomy (removal of the ovaries) to reduce the chances of developing breast or ovarian cancer in the future.
[See: What Not to Say to a Breast Cancer Patient.]
Senter says “in general, all the red flags are universal and not specific to one ethnic background over another.” Therefore, no matter what your heritage is, it’s a good idea to know your family’s health history. Although genetic testing may not be necessary for everyone, it’s a tool in the doctor’s arsenal if there is reason for concern and a need for more information for you or your family.
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What Makes Ashkenazi Jews More Susceptible to Breast Cancer? originally appeared on usnews.com
