Genetic Testing Purposes
There are several purposes for genetic testing, and so several types of genetic tests. We normally think of DNA testing, but gene testing can also look at RNA, chromosomes (DNA), proteins, and some chemical byproducts. This testing can detect some heritable genotypes, mutations, phenotypes, or karyotypes that are related to disease. Available types of genetic tests include:
- Carrier testing identifies people who carry one copy of a mutant gene responsible for causing a particular disease or disorder. For some such mutations, if both parents carry it then any of their offspring has a much higher risk of developing the disease or disorder. Carrier genetic testing is offered to persons with a family history of a genetic disorder and, in some cases, to people in ethnic groups with an increased risk of specific genetic conditions. Following the testing of both parents, predictions of their risk of having a child with a genetic condition can be made.
- Prenatal testing of fetuses or amniotic fluid can be performed before birth to detect diseases like Down's syndrome. Couples with an increased risk of having a baby with a genetic or chromosomal disorder may utilize this genetic testing. Prenatal testing often can lessen uncertainty or help a couple decide upon possible abortion of the pregnancy. Gene testing does not identify all possible birth defects and inherited diseases, syndromes and disorders.
- Neonate or newborn genetic screening can be performed just after birth to detect genetic disorders which are treatable early in life. Millions of infants are tested each year in the United States, making this the most common use of genetic testing. All of the United States require that infants be DNA tested for PKU (phenylketonuria, a genetic disorder that that causes mental retardation but can be avoided by diet changes) and congenital hypothyroidism (a treatable disorder of the thyroid gland).
- Paternity testing is used to determine the father, the baby daddy, of a child or even an adult. Home test kits are available from online vendors for these tests, which are considered to be highly accurate.
- Diagnostic testing is used to diagnose and confirm or rule out a particular genetic or chromosome-related condition. Often, genetic testing can confirm a diagnosis that is suspected on the basis of symptoms, chemical values and physical manifestations. Diagnostic genetic testing can be done at any time during the life of the patient. Genetic tests are not available for all genes or all genetic conditions.
- Predictive genetic testing can be performed in pre-symptomatic situations to detect gene mutations associated with disorders that appear after birth, often in middle age or old age. These DNA tests are often requested by apparently-healthy people with a blood relative afflicted with a genetic disorder. Predictive testing can identify genetic mutations known or believed to increase the chance of developing genetics-related disorders, including certain types of cancer. For example, women with a mutation in BRCA1 have a much higher risk of breast cancer. Presymptomatic testing can accurately predict if a person will develop a genetic disorder, such as hemochromatosis (iron storage disease), before symptoms appear. The results of predictive testing and pre-symptomatic genetic testing can clarify a person’s risk of developing a specific disorder and help make decisions about medical care.
- Forensic testing uses DNA genetic sequences to identify an individual for legal or military purposes. Crime testing can identify crime victims, victims of military or terrorist actions, or natural catastrophes. Additionally, forensic genetic testing can rule out or implicate a crime suspect. Paternity testing (listed above) is a form of forensic testing.
- Research testing involves identifying unknown genes, studying how genetic mechanisms work and improving the understanding of genetic conditions.
