Understanding how genes play a part in our risk for breast cancer can be difficult—especially since terms like, “genetic abnormality” and “genetic mutation” are often thrown around without much explanation. Thanks to a podcast series with licensed, certified genetic counselor Cristina Nixon, we’ve got simple explanations and digestible tidbits for you to start your genetics education journey.
• To start, what are genes? Genes are short segments of DNA that tell our cells how to perform specific functions. DNA is made up of four chemicals and each gene has its own unique spelling of the chemical code. Genes are in every cell of our body and they’re inherited from both of our parents.
• So what are abnormal genes? When an alteration occurs within that chemical code in the DNA, an abnormal gene is then created. Because of this alteration, the gene isn’t able to interpret its unique instructions and isn’t able to function as well (sometimes it isn’t able to function at all!). Some abnormal genes aren’t harmful—these are referred to as “benign changes”—and some gene alterations are harmful—we call these gene mutations. Sometimes, even with disease-causing mutations, you may never know about the altered gene because the disease hasn’t shown up yet, or in some cases, may never show up. Sometimes it’s just a predisposition to a certain disease.
• Are all mutations inherited? Nope! In fact, most mutations are actually acquired during your lifetime from exposure to something in the environment, from lifestyle factors (like smoking), or simply because of mistakes that happen in the DNA as cells grow and divide. Inherited mutations—a.k.a., mutations passed down from mom and dad—are in every cell of the body, whereas acquired mutations usually only occur in one gene of one cell in the body.
• How do BRCA1 and BRCA2 genes come into play? If there are no mutations and both genes are functioning as they’re supposed to, BRCA1 and BRCA2 are tumor suppressor genes—it’s their job to prevent cells from growing into tumors. But when either parent passes down a mutation, or if both parents pass down mutations, the risk for certain types of cancer increases because the genes aren’t functioning properly.
• What kinds of cancer do mutated BRCA1 and BRCA2 genes cause? There’s a well-documented link between mutated BRCA1 and BRCA2 genes and a heightened risk of breast cancer. However, there’s also a increased risk for ovarian cancer, pancreatic cancer and melanoma. Men also have a heightened breast cancer risk, plus around a 20 percent higher risk for prostate cancer.
• Are there other gene mutations that can lead to breast cancer? While BRCA1 and BRCA2 are the most common genes to cause hereditary breast cancer, mutations in the TP53, PTEN, CDH1 and STK11 genes, among others, can also cause an increased breast cancer risk. The risk of carrying a mutation in either BRCA1 or BRCA2 is anywhere between 1 in 500 to 1 in 800, which puts into perspective how unlikely these mutations are in the general population.
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