Genes most often are an indication, not a guarantee
Many things about you are at least partly determined by variations in your genes, which you inherit from both of your parents. The risk of you or your child inheriting a genetic mutation, sometimes called a genetic variant, depends on a variety of factors, including your parents’ genes, your genes, the disease itself and, well, math. It’s also important to understand that genes don’t determine everything.
We don’t yet know what every gene mutation means. We learn more every year, and in 30 years, we will be closer to understanding every mutation. In the meantime, genetic test results can sometimes be inconclusive because a test will show a mutation for something that we don’t yet comprehend (this is called a variant of unknown significance). In other cases, even when there is a strong family history of a disease, we don’t find the genetic mutation. That doesn’t mean it’s not there, but because there are so many possible mutations, we may not have found it. Overall, though, genetic testing is very accurate. Most tests are more than 90 percent accurate, and some are 99 percent accurate.
Still, there are many misconceptions and misunderstandings about genetic testing. Here’s what you should know:
- A positive genetic test result does not mean you definitely will get a particular disease. It may tell you if you have a genetic mutation, which might mean you are at increased risk for the condition tested, such as cancer. But it doesn’t mean you will definitely get that cancer or other diseases because lifestyle and your environment also are factors. If you learn you are at risk, genetic testing can help you make decisions, such as eating healthier, exercising more and being tested (screened) regularly for that cancer or condition.
- A negative genetic test result does not mean you definitely won’t get a particular disease. Many cancers do not have a genetic component. For example, only one-third of people with breast or colon cancer have a family history. That means many people get these cancers without inheriting a gene for it. And in some cases, there may be a genetic link, but we can’t test for it because not all genes that cause cancer have been discovered.
So why test at all? There are several reasons to consider testing:
- Screening – There are special screening tests available for some conditions, such as cancer. For example, if you learn you are at higher risk for breast cancer, you might choose to begin having mammograms when you are younger, or even have more advanced testing, such as an ultrasound or MRI. The same holds true for many other cancers. When cancer is caught earlier, treatment is usually more effective.
- Lifestyle changes – Knowing you are at higher risk for a genetic disease might nudge you to make healthier lifestyle choices that can decrease your risk. For example, you may choose to eat healthier, exercise more, stop smoking and drink less alcohol.
- Prophylactic surgery – Some women with a BRCA1 or BRCA2 mutation choose surgery to remove their breasts or ovaries, which significantly decreases their risk of cancer.
- Personalized treatment – Some genetic diseases respond better to certain treatments. If you are diagnosed with a cancer that has a genetic link, or are at risk for such a cancer and eventually develop it, you can be given better, more effective treatment.
- Informing your family – Sharing the information you learn from your test results with your family gives them a chance to think about whether they would like to get tested.
Genetic tests are available for some conditions (such as Alzheimer’s disease) even though no cure or treatment is available. Still, there are several reasons some people opt to get tested:
- Decision making – Learning you tested positive might help you make decisions. For example, if you are planning to have children, you may want to try to avoid passing a mutation on to them by having assisted reproduction and preimplantation testing. You might conceive naturally and have a test during pregnancy to learn if your baby has the variant. Or you may decide not to have children, or pursue other options such as adoption.
- Empowerment – For some people, knowing that they are likely to develop a condition or disease is less stressful than not knowing. It helps them make healthcare and lifestyle adjustments they might not otherwise.
- Easing stress – This is a risk, but if you do not test positive, the result may ease the stress of not knowing.
Some may choose not to get tested because they find the risk of getting a positive result too stressful, especially in cases when there is no treatment available.
This is why seeing a genetic counselor can be very helpful. A genetic counselor will:
- Help you understand what genetic tests exist and what they may or may not find
- What the options are if you do decide to have testing
- Listen to your concerns and thoughts and help you figure out the best way forward for you and your family
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