Genetic testing is a voluntary type of medical test used to identify changes in chromosomes, genes, or proteins. This type of medical test checks for alterations in an individual's genes or changes in levels of gene products, proteins. Genetic testing could also be used to look for structure of certain proteins, and for levels of RNA that play a role in certain conditions. The purpose of the test is to indentify genetic problems or possible risk for developing genetic disease. What could genetic testing be used to identify? Molecular genetic tests (or gene tests) are designed to use single genes or short factions of DNA in order to identify changes or mutations that lead or may lead to a genetic disorder. Zooming out a little from the molecular level, a chromosomal genetic test is used to analyze whole chromosomes or long fragments of DNA, to check if there are big genetic changes, such as an extra copy of a chromosome. In case of studying gene products, the biochemical genetic test is done to study the amount of protein or activity level of a certain proteins that is known to be important in a genetic disorder.
Genetic testing may be used for many purposes. A reason for genetic testing is diagnostic testing, which is used to identify or rule out a specific genetic or chromosomal condition. This is used mainly with the purpose to confirm a diagnosis when a genetic condition is suspected based on physical signs and symptoms. Diagnostic testing can be performed at any time in the lifespan, including before birth. Similar in purpose to the diagnostic testing is the carrier testing, mainly used to identify if a person is heterozygous for a mutation. This type of testing would be best fit for individuals who have a family history of a genetic disorder and perhaps wish to know if they will pass it to their children.
While we could argue the above tests to be common for adults, tests designed for newborns and even fetuses exist. A newborn screening is best to identify genetic disorders that could be possibly treated early in life. This test is done on millions of babies each year in the United States. Diseases most commonly tested for with this test include phenylketonuria, congenital hypothyroidism and other. Before birth, prenatal testing is used to detect mutations in a fetus. This test is done when during pregnancy there is an increased risk that the baby will have a genetic or chromosomal disorder. Going back to the very beginning of a pregnancy a tests can be done, called preimplantation testing. This test is also called preimplantation genetic diagnosis (PGD), and is a specialized technique that can reduce the risk of having a child with a particular genetic or chromosomal disorder. The test is used to detect genetic changes in embryos from in-vitro fertilization, and in-vitro fertilization. To perform preimplantation testing, usually a small number of cells are taken from the embryo and tested for certain changes in genetic material.