A mutation in a person's DNA can cause a disruption in normal function. In some cases, the DNA mutation may not result in any symptoms until the patient has reached adulthood. According to the National Institutes of Health, "genetic tests are tests on blood and other tissue to find genetic disorders. About 900 such tests are available." Genetic testing can be used to find a DNA mutation to detect or confirm a disorder, find a carrier gene or determine if a fetus or newborn has a genetic disorder.
Diagnostic Testing
According to the Mayo Clinic, diagnostic testing can be used to either reveal if a patient has an adult onset disorder, such as Huntington's disease, or confirm a diagnosis. A diagnosis of polycystic kidney disease, hemochromatosis and Charcot-Marie-Tooth disease can be confirmed with a DNA diagnostic test. Diagnostic testing is performed by drawing a sample of blood from the patient. Then, the diagnostic laboratory tests the blood for the presence of the DNA mutation that causes the disorder. In the case of adult onset disorders, diagnostic testing is done if the patient either has symptoms or a family history of the disease.
Carrier Testing
Carrier testing is another form of testing for a DNA mutation. According to the Mayo Clinic, a carrier test is done when a couple wants to conceive a child but is worried about passing on a genetic disorder, such as sickle cell anemia or cystic fibrosis. First, a blood sample is taken from each of the parents. Then, like other DNA mutation tests, the diagnostic laboratory analyzes the blood samples for the presence of the mutation. However, both parents must be carriers of the DNA mutation for the child to have the disorder. If only one parent passes the DNA mutation to the child, then the child becomes a carrier as well.
Prenatal and Newborn Screening
Prenatal testing is used to test for abnormalities in a fetus, according to the Mayo Clinic. Examples of DNA mutations that are screened for in prenatal testing are spina bifida and Down syndrome. Prenatal testing uses either amniotic fluid or a placenta sample to test for a DNA mutation. However, there are ethical issues surrounding prenatal testing. The screening is done early in the pregnancy, giving the mother the option to abort; some people object, saying that it discriminates against disabled children. In addition to prenatal testing, newborn screening is also done. According to the Mayo Clinic, many states require newborns be screened for certain disorders, such as congenital hypothyroidism and phenylketonuria. A blood sample is drawn soon after birth, and the laboratory screens for the DNA mutation. The purpose of newborn screening is to provide early treatment for the baby.
