You may have heard about the term – Genetic test, but you are not sure what actually is meant by this term. And that’s the reason why you are here! If so, let’s learn about it in this interactive post.
What do we mean by genetic testing?
Genetic testing is a method to determine if there are any changes in your genes.
Why do one want to have genetic testing?
With genetic testing, you can understand your risk for certain diseases. It can also help you make decisions about screening and treatment.
What are genes and what do they do?
Genes are made of DNA, which is inside every cell in the body. The genes are basically the codes for the body structure and function. They tell your cells how to make different proteins, and they give instructions about how your body should work. For example, your genes tell the body to make different organs while in the mother’s womb.
After you are born, your genes tell your body how to work normally. It is your genes that determine things like your eye color.
Your complete set of genes is called your “genome.” Everyone’s genome is unique. That’s why people’s bodies all look and work differently. Genes are stored in the chromosomes. You get, or inherit, your genes from both of your parents. Humans have about 20,000 to 30,000 different genes.
Genes often have changes in the DNA called “variants” or “mutations.” These variants sometimes affect the way your body makes proteins. In some cases, these variants can put you at risk for disease, while in other cases, these changes do not have any effect at all. Sometimes, they might cause a slight change that is neither better nor worse. Or, experts might not know enough about the change to understand how it will affect you.
How does genetic testing work?
Genetic tests can look for variants that are linked to lots of different conditions. There are several kinds of tests. The differences include:
- Number of genes tested– Some tests look at 1 gene. Some tests look at a bunch of genes. And some tests look at a person’s entire genome (all the genes).
- Type of results given– Some tests look for specific gene changes that are related to a disease. In these cases, the results are reported as positive or negative. A positive result means you have the variant, while a negative result means you don’t. Other tests look at an entire gene or a group of genes to see if any of the genes have changes. Sometimes, a test comes back with the result “variant of unknown significance.” This means it’s not known if the change is related to a disease or might increase your risk of disease. In the future, it might be known after more research is done.
- Type of sample used– All the tests require DNA, which comes from cells in your body. Some tests use blood, and some use saliva. Some use other fluids. For example, there are tests that look at samples of an unborn baby’s cells (for a pregnant person) or of tumor cells (for a person with cancer).
Why do people get genetic testing?
People get genetic testing for different reasons:
- Some pregnant women have genetic testing on their baby before it is born. This involves testing a sample that contains cells from the developing baby (fetus). The sample can come from your blood or from your uterus. Doctors might recommend this testing if a disease runs in your family or if you have an ultrasound (imaging test) that shows problems with the fetus.
- If you develop symptoms of a disease or get abnormal lab test results, your doctor might suggest genetic testing. This can help them figure out if you have the disease.
- If you already have a disease, you might want to know if you have a genetic variant related to that disease. If you do have a certain variant, knowing this might affect your treatment options. Your family members can use this information to decide if they want to get tested, too.
- If you have a family member who has a disease or tested positive for a genetic variant, you might want to know if you are also at higher risk. For example, hemochromatosis is a disorder that causes your body to take in too much iron. If one of your family members has the abnormal genes for this, you might choose to be tested.
- You might want to find out if you are a “carrier” for a certain genetic variant, to see if you could pass it on to your children. Being a carrier means you inherited an abnormal gene from one of your parents, but you do not have the disease. That’s because you have to inherit two copies of an abnormal gene (one from each parent) to actually get the disease. Some examples of diseases that work this way are cystic fibrosis and sickle cell anemia. If both parents are carriers, there is a chance that their children could inherit the gene from both parents and get the disease.
How do I decide whether to get genetic testing?
Your doctor or a genetic counselor can help you make this decision. A genetic counselor is a person who knows about many genetic diseases and can help you understand your options. They can talk to you about what your test results might mean for you and your family.
Questions to think about include:
- What you are hoping to learn from genetic testing
- Your risk for certain diseases or conditions that run in your family
- What costs might be involved in testing
- What your test results might mean for you
- What your test results might mean for your family
- Your options for more testing or treatment based on the results
- Lifestyle changes you can make to help lower your risk of disease
A doctor or genetic counselor can also help with some of these questions:
- What genes are being tested, and what are the related diseases?– In most cases, genetic testing helps you understand if you are at a greater risk of having a disease. But it can’t tell you for sure if you will get the disease. In most cases, only the most common genes for a disease are tested.
- What do I plan to do with this information?– If you are planning to have children, it can be helpful to know whether you are a carrier for a genetic variant, especially if certain diseases run in your family. A doctor or genetic counselor can explain the risk of your future children having the disease.
Sometimes, if you know that you have a genetic variant, you can do things to help lower your risk of getting a disease later in life. For example, you might be able to change your diet or other behaviors. It’s usually not possible to completely prevent a disease.
If you already have a disease, the results might help you decide on the best treatment plan.
Deciding to get genetic testing is not always easy. It’s also not always clear what to do once you have the results. Your doctor or genetic counselor can help you talk through your feelings and worries.
What does that mean for me if I get a positive result?
Testing positive for some genetic variants means that you might be at higher-than-average risk for a certain disease. It does not always mean you have that disease or will get it later in life.
Knowing that you have a genetic variant can be upsetting or stressful to some people, so some people prefer not to know this, especially if there’s nothing they can do about it.
What does it mean if the result is negative?
A negative result does not mean you will not get the disease. It only means that the gene the test looked at is normal. But most diseases can have other causes, including things in your environment.
What should I do about my genetic test results?
Discuss your results with your doctor or genetic counselor. They can help you understand what the results mean.
If you already have a disease, knowing that you have a specific variant might affect your treatment options. For example, some medicines used to treat cancer only work if the person has a certain genetic variant. Your doctor or genetic counselor can talk to you about your situation and your choices.
Can I buy my own genetic testing kit?
Yes, there are companies that sell at-home testing kits. These are also called “direct-to-consumer” tests. You can buy the kit, then follow the instructions and mail a sample of your saliva to a lab for testing. But your doctor might not be able to use the results from these kits, or might need to repeat the test. If you think you might have a disease gene, talk to your doctor directly.
Some companies test for variants in certain genes. Some only test for genes that tell about your ancestry, that is, what parts of the world your relatives came from. Different companies offer different tests, and it’s not always possible to know how accurate they are. If you do want to try an at-home testing kit to look at how your genes might affect your health, or if you have already tried one, it’s a good idea to talk with your doctor about it.
