Genetic testing uses laboratory methods to look at your genes, which are the DNA instructions you inherit from your mother and your father.
How are genetic tests used?
Genetic tests may be used to identify increased risks of health problems, to choose treatments, or to assess responses to treatments.
What can I learn?
There are many different types of genetic tests. Genetic tests can help to:
Identify gene changes that are responsible for an already diagnosed disease
Determine the severity of a disease
Guide doctors in deciding on the best medicine or treatment to use for certain individuals
Identify gene changes that may increase the risk to develop a disease
Identify gene changes that could be passed on to children
Screen newborn babies for certain treatable conditions
Genetic test results can be hard to understand, however specialists like geneticists and genetic counselors can help explain what results might mean to you and your family. Because genetic testing tells you information about your DNA, which is shared with other family members, sometimes a genetic test result may have implications for blood relatives of the person who had testing.
What are the different types tests?
Diagnostic testing is used to precisely identify the disease that is making a person ill. The results of a diagnostic test may help you make choices about how to treat or manage your health.
Predictive and pre-symptomatic genetic tests are used to find gene changes that increase a person's likelihood of developing diseases. The results of these tests provide you with information about your risk of developing a specific disease. Such information may be useful in decisions about your lifestyle and healthcare.
Carrier testing is used to find people who "carry" a change in a gene that is linked to disease. Carriers may show no signs of the disease; however, they have the ability to pass on the gene change to their children, who may develop the disease or become carriers themselves. Some diseases require a gene change to be inherited from both parents for the disease to occur. This type of testing usually is offered to people who have a family history of a specific inherited disease or who belong to certain ethnic groups that have a higher risk of specific inherited diseases.
Prenatal testing is offered during pregnancy to help identify fetuses that have certain diseases.
Newborn screening is used to test babies one or two days after birth to find out if they have certain diseases known to cause problems with health and development.
Pharmacogenomic testing gives information about how certain medicines are processed by an individual's body. This type of testing can help your healthcare provider choose the medicines that work best with your genetic makeup.
Research genetic testing is used to learn more about the contributions of genes to health and to disease. Sometimes the results may not be directly helpful to participants, but they may benefit others by helping researchers expand their understanding of the human body, health, and disease.
What are the benefits and drawbacks?
Benefits: Genetic testing may be beneficial whether the test identifies a mutation or not. For some people, test results serve as a relief, eliminating some of the uncertainty surrounding their health. These results may also help doctors make recommendations for treatment or monitoring, and give people more information for making decisions about their and their family's health, allowing them to take steps to lower his/her chance of developing a disease. For example, as the result of such a finding, someone could be screened earlier and more frequently for the disease and/or could make changes to health habits like diet and exercise. Such a genetic test result can lower a person's feelings of uncertainty, and this information can also help people to make informed choices about their future, such as whether to have a baby.
Drawbacks: Genetic testing has a generally low risk of negatively impacting your physical health. However, it can be difficult financially or emotionally to find out your results.
Emotional: Learning that you or someone in your family has or is at risk for a disease can be scary. Some people can also feel guilty, angry, anxious, or depressed when they find out their results.
Financial: Genetic testing can cost anywhere from less than $100 to more than $2,000. Health insurance companies may cover part or all of the cost of testing.
Many people are worried about discrimination based on their genetic test results. In 2008, Congress enacted the Genetic Information Nondiscrimination Act (GINA) to protect people from discrimination by their health insurance provider or employer. GINA does not apply to long-term care, disability, or life insurance providers. (For more information about genetic discrimination and GINA, see http://www.genome.gov/10002328/genetic-discrimination-fact-sheet/).
Limitations of testing: Genetic testing cannot tell you everything about inherited diseases. For example, a positive result does not always mean you will develop a disease, and it is hard to predict how severe symptoms may be. Geneticists and genetic counselors can talk more specifically about what a particular test will or will not tell you, and can help you decide whether to undergo testing.
How do I decide whether to be tested?
There are many reasons that people might get genetic testing. Doctors might suggest a genetic test if patients or their families have certain patterns of disease. Genetic testing is voluntary and the decision about whether to have genetic testing is complex.
A geneticist or genetic counselor can help families think about the benefits and limitations of a particular genetic test. Genetic counselors help individuals and families understand the scientific, emotional, and ethical factors surrounding the decision to have genetic testing and how to deal with the results of those tests.