Several types of genetic testing are done for different reasons:
- Diagnostic testing. If you have symptoms of a disease that may be caused by genetic alterations, genetic testing can reveal if you have the suspected disorder. Examples of disorders for which genetic testing may be used to confirm a diagnosis include adult polycystic kidney disease, iron overload (hemochromatosis) and Charcot-Marie-Tooth disease.
- Presymptomatic and predictive testing. If you have a family history of a genetic condition, undergoing genetic testing before you have symptoms may show if you're at risk of developing that condition.
- Carrier testing. If you have a family history of a genetic disorder — such as sickle cell anemia or cystic fibrosis — or you are in an ethnic group that has a high risk of a particular genetic disorder, you may choose to have genetic testing before you have children. An expanded carrier screening test can detect genes associated with a wide variety of genetic diseases and mutations.
- Pharmacogenetics. If you have a particular health condition or disease, this type of genetic testing may help determine what medication and dosage will be most effective and beneficial for you.
- Prenatal testing. If you are pregnant, tests are available that can detect some types of abnormalities in your baby's genes. Down syndrome and trisomy 18 are two genetic disorders that are often screened for as part of prenatal genetic testing.
- Newborn screening. This is the most common type of genetic testing. In the United States, all states require that newborns be tested for certain gene abnormalities that cause specific conditions. This type of genetic testing is important because if results show there's a disorder such as congenital hypothyroidism or phenylketonuria (PKU), care and treatment can begin right away.
- Preimplantation testing. Also called preimplantation genetic diagnosis, this test may be used when you attempt to conceive a child through in vitro fertilization. With in vitro fertilization, eggs are removed from a woman and sperm are collected from a man. The eggs are then fertilized with the sperm outside the body to create embryos. The embryos are then screened for genetic abnormalities. Embryos without abnormalities are implanted in the uterus in hopes of achieving pregnancy.