8.2 Genetic Testing Overview
What is genetic testing?
Genetic testing is a type of medical test that looks for changes in DNA. Genetic tests analyze cells or tissue to look for changes in genes, chromosomes, and proteins.
Genetic testing may be done for many different reasons:
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 information about the risk of developing a specific disease. Such information may be useful in decisions about lifestyle and healthcare.
Carrier testing is used to find people who “carry” gene variants linked to disease. Carriers may show no signs of the disease. However, they can 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 is usually 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. This type of testing is offered during pregnancy if there is an increased risk that the baby will have a genetic or chromosomal disorder. In some cases, prenatal testing can lessen a couple’s uncertainty or help them make decisions about a pregnancy. However, it cannot identify all possible inherited disorders and congenital disabilities.
Newborn screening is used to test babies one or two days after birth to determine if they have certain diseases that cause health and development problems.
Pharmacogenomic testing gives information about how an individual’s body processes certain medicines. This type of testing can help healthcare providers choose the drugs that work best with an individual’s genetic makeup.
Research genetic testing is used to learn more about the contributions of genes to health and 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 of genetic testing?
Genetic testing may be beneficial whether the test identifies a mutation or not. Test results are a relief for some people, eliminating some 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 their chance of developing a disease. For example, as a result of such a finding, someone could be screened earlier and more frequently for the disease and could change 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 make informed choices about their future, such as whether to have a baby.
What are the risks and limitations of genetic testing?
The physical risks associated with most genetic tests are minimal, particularly for those tests that require only a blood sample or buccal smear. The procedures used for prenatal diagnostic testing carry a small but real risk of miscarriage because they require a sample of amniotic fluid or tissue from around the fetus.
Many of the risks associated with genetic testing involve the results’ emotional, social, or financial consequences. 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.
People may feel angry, depressed, anxious, or guilty about their results. Because family members share DNA, some family members may have the same variants. For this reason, in some cases, genetic testing creates tension within a family.
Genetic testing can provide only limited information about an inherited condition. The test often can’t determine if a person will show symptoms of a disorder, how severe the symptoms will be, or whether the disorder will progress over time. Another major limitation is the lack of treatment strategies for many genetic disorders once they are diagnosed.
The possibility of genetic discrimination in employment or insurance is also a concern. This will be explored in greater detail in chapter 10.2.
Attribution & References
Except where otherwise noted, this section is adapted from
- What is genetic testing? section from Genetic Testing by MedlinePlus, National Library of Medicine, Public Domain with Attribution
- What are the benefits of genetic testing? from Genetic Testing FAQ Courtesy: National Human Genome Research Institute (NHGRI), Public Domain with attribution
- What are the risks and limitations of genetic testing? from What are the risks and limitations of genetic testing? and What is the cost of genetic testing, and how long does it take to get the results? In Help Me Understand Genetics by MedlinePlus, Public Domain with attribution
