Genetic testing looks for specific inherited changes (variants) that increase your risk of developing diseases such as cancer. But a negative test result doesn’t guarantee you don’t have the disease-causing gene.
Also, a positive test result doesn’t tell you how severe your symptoms may be or when they might occur. This can be upsetting or confusing.
Cannot be detected in a genetic test
In some cases, even when a genetic test detects a mutation that is known to cause disease, the test cannot predict whether or not disease symptoms will ever appear. This is called incomplete penetrance, and it can occur because other genes or environmental factors are also necessary for disease expression.
Some genes may also have more than one variant that can cause the same disease, called polymorphisms. A gene test can also return a result of a “variant of uncertain significance,” or VUS, meaning that the variant has not been shown to increase or decrease a person’s risk for disease.
People should receive information about the limitations of their tests from their healthcare provider or genetic counselor before they have a test. They should also be informed about the likelihood that their results will become part of their medical records and how they will likely be used. People should be able to discuss with their doctor and family members any questions or concerns about the testing limitations and how their results might impact their lives.
Because the information provided by genetic tests is limited, people must consider genetic testing to understand and weigh the benefits and risks of testing against the alternatives of not having a test or delaying testing until later in life when they may have more treatment options.
Healthcare professionals must ensure that people understand the limitations of a particular test before ordering it, and people who choose to have the test must give their written consent after being fully informed.
The committee recommends that all persons who request a genetic test be offered counseling with a qualified genetic counselor before the test is performed. The counselor can explain the limitations of the test and help a person decide if the test is appropriate for their situation. If a person does not receive adequate counseling before the test, they may be unnecessarily anxious or confused about their results.
There are insufficient trained medical geneticists and counselors to provide genetic testing for everyone who wants it. As a result, most genetic screening will likely be conducted by primary care physicians, such as family physicians, internists, and obstetrician-gynecologists. These providers may not have the time or inclination to offer extensive, in-depth genetic counseling. This raises concerns about the quality of genetic testing and interpretation and the potential for improper use of genetic test results.
Can be detected in a genetic test
Genetic testing is a way to find out if you have changes in your genes that make you more likely to get certain medical problems, such as some cancers. It can also tell you if you are at risk of passing these genes to your children.
Genes are the building blocks of the body, and they help control how the body works. Genetic changes are called mutations and can affect your chances of getting a disease or condition. Genetic tests look for variations in a person’s genes, chromosomes, and other tissues. They may involve blood, urine, swabs from the mouth or skin, saliva samples, hair samples, or cells taken from tissue such as the lung or liver.
Some genetic tests focus on a single gene, while others check for changes in a group of genes at the same time. These tests are often called multigene or panel tests. People usually have these tests when they are considering whether to get a test or when the doctor thinks it is important for them to know their risk level.
Many people who have genetic tests decide not to get the results, especially if they don’t feel the information will change their medical care or decisions. This is because genetic testing doesn’t always give useful information. Some inherited gene mutations don’t cause any symptoms or increase the chance of developing a disease. Other genetic mutations may increase a person’s risk by only slightly or not at all.
A test can reveal only a small percentage of mutations that can increase a person’s chances of getting a disease, and even then, the test cannot guarantee that the person will develop the disease. There are several reasons why this is true.
One reason is that other factors, such as environmental influences and lifestyle choices, can influence a person’s chances of developing a disease even when they have a particular gene mutation. The other is that scientists are still learning how genes influence the risk of disease. Many common diseases like heart disease and cancer are not yet tied to specific gene mutations.
Genetic tests can sometimes provide a less clear picture than people expect. For example, a genetic test for breast cancer can find a mutation that increases the chance of developing the disease, but it is not possible to say with certainty that the person will definitely develop the disease. In addition, some people have mutations that are not linked to increased cancer risk and are referred to as variants of uncertain significance.
Depending on the results of the test, it may be helpful for people to talk with a health professional, such as a genetic counselor, before they decide to have the test. This person can help them gather and review family medical history, understand the risks and benefits of the test, discuss options for follow-up testing if needed, and prepare for any reactions to the results. The counselor can also help them decide whether they should have the test done for themselves or family members.
