Definition and Overview
Genetic testing, sometimes referred to as DNA testing, is a medical term that refers to a number of tests performed to determine changes and abnormalities in the genetic composition of a person using samples of chromosomes, genes, and proteins. One common example is the molecular genetic test in which mutations are detected in short DNA sequences or single genes. Another type, the chromosomal genetic test, is the analysis of chromosomes or longs strands of DNA to evaluate the cause of a certain genetic condition. These tests are voluntary and performed in laboratories, with results interpreted by geneticists.
Who Should Undergo and Expected Results
Understandably, genetic testing is not advisable for all types of people. Since it involves the assessment of mutation in the genetic makeup of a person, the results would also have an impact on the rest of the family who likely share the same genetic composition.
Families with a higher likelihood of developing a certain type of disease are advised to undergo DNA testing. The results would be beneficial in determining who are at risk and can be used to make informed lifestyle decisions. A particular person who may be a carrier of an inherited disease and those belonging to certain ethnic groups that might also be predisposed to a specific medical condition can also undergo the tests.
In some instances, physicians who have a difficulty diagnosing a particular medical condition advise their patients to undergo DNA testing to come up with an effective treatment plan.
Pregnant women carrying fetuses at risk for certain disorders are also advised to undergo genetic testing to identify conditions that would impact their development.
A positive result confirms a previous diagnosis or the patient’s risk of a certain inherited disease. It could also determine if the person is a carrier of a mutated gene. It could not, however, predict the severity of a certain condition nor its outcome.
A negative result, on the other hand, would indicate that no mutation or change was detected in a specific gene, DNA sequence, or protein tested. This means that the person is not a carrier, not at risk, nor is affected by a specific disease or disorder.
In some cases, tests might give out uninformative, ambiguous results in which the detected DNA change is not associated with any medical disorder in other people. This typically requires further testing to get conclusive and clear results.
How Does the Procedure Work?
Genetic testing typically starts with the collection of either one or a combination of the following biological samples:
- Blood extracted from a vein or pricked from the heel of a newborn
- Amniotic fluid extracted from the uterus of a pregnant woman
- Tissues from specific body parts or organs
- Swab samples from the inside of a cheek
- Other biological samples such as hair, skin, or body fluids
Possible Complications and Risks
While there are several benefits associated with genetic testing, there are also risks and possible complications.
One is the emotional impact of genetic testing. Knowing that the person or a loved one can develop a debilitating or fatal disease could create feelings of grief or depression. For this reason, those who undergo genetic testing are advised to consult a genetic counselor to help them deal with the whole process. A professional genetic counselor would be able to answer questions and provide advice on how to deal with the test results.
Genetic testing cannot also provide comprehensive information about the disease a person is at risk for. Up to a certain point, the results would help in the prevention and management of a certain condition but cannot definitely predict how or when a disease would develop and to what extent.
In a broader sense, genetic testing could provide an avenue for discrimination by employers or insurance providers who might opt not to provide benefits to people who are predisposed to or at risk of certain conditions.
Genetic testing might also take a financial toll on families, with costs ranging from hundreds to thousands of dollars. Some of the tests might be covered by medical insurance but others require out-of-pocket expenses.
Simpson JL, Holzgreve W, Driscoll DA. Genetic counseling and genetic screening. In: Gabbe SG, Niebyl JR, Simpson JL, eds. Obstetrics: Normal and Problem Pregnancies. 6th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2012:chap 10.
Simpson JL, Richards DA, Otao L, Driscoll DA. Prenatal genetic diagnosis. In: Gabbe SG, Niebyl JR, Simpson JL, eds. Obstetrics: Normal and Problem Pregnancies. 6th ed. Philadelphia, PA: Elsevier Churchill Livingstone; 2012:chap 11.