When might genetic testing might be helpful?
Preconception testing. Before you or your partner are pregnant, preconception genetic testing can tell if there is a higher chance for your pregnancy to be affected by an inherited condition. You may consider this because you are aware of an inherited condition in your family. This is often called carrier testing. It can identify a change in a gene that does not cause any health problems for you; you are simply ‘carrying’ the gene change. If you and your partner are each carriers of a change in the same gene, you would be more likely to have a child with an inherited condition. You may also ask about this because you are part of an ethnic group in which an inherited condition is more common. Some couples are offered carrier screening as a routine part of preconception care.
Preimplantation genetic testing. If you or your partner are using alternative reproductive technology (ART) to conceive a pregnancy, you may be offered this testing. It is also known as preimplantation genetic diagnosis (PGD). Shortly after the pregnancy is conceived, cells from the pregnancy are tested to determine if the conception has one or more specific inherited conditions.
Prenatal testing. If you or your partner are pregnant, you may use prenatal testing to help diagnose an inherited condition in the developing baby. Sometimes, you may be offered a screening test, which can’t diagnose a condition by itself. Screening tests will let you know whether there is a higher or lower chance that the baby will inherit one or more health conditions. You may then choose follow-up testing that is diagnostic to tell you for sure. You may also decide to have diagnostic testing without having a screening test.
Newborn screening. All newborn infants receive this type of genetic testing. Newborn screening is used to detect inherited conditions, many of which have early treatments available. This is done by a heel stick that collects a small blood sample. If you are the parent of a newborn, you will be informed if results suggest that your baby has an inherited condition. You may then be offered follow-up testing to be sure.
Diagnostic testing. If you or your child have symptoms of an inherited condition, you may have genetic testing to learn if there is a genetic cause. A diagnosis may change your medical management. This could mean you need to have a certain screening test more often (like a colonoscopy). It could also mean that you can lower your chance for getting future symptoms by taking medications or by having surgery (like a mastectomy, or removal of breast tissue to lower the chance for breast cancer). Sometimes, finding a diagnosis will not lead to changes in your medical management. It may still be helpful to know the cause of your symptoms. If a disease-causing genetic variant is found in you, it may allow other family members to have predictive genetic testing.
Somatic tumor testing. If you have cancer, you might have your tumor tested to identify somatic (or tumor-specific) gene variants. Some variants may help the health care provider choose a treatment. Results of testing may determine eligibility for a clinical trial. Sometimes tumor testing can uncover gene variants that are inherited and may increase the chance that your relatives will develop cancer.
Predictive testing. If you have a relative with an inherited condition, you may be offered predictive testing to determine whether you are likely to develop that condition. For this testing to be possible, the genetic variant causing the inherited condition in the family must be known. Testing may allow you to have earlier screening to avoid disease onset or serious complications. For some inherited conditions, there may not be different medical recommendations. A certified genetic counselor can help you as you consider whether or not predictive testing would be helpful to you.
Research testing. You may be offered genetic testing as part of a research study. The goals of research testing are to discover new genes or to develop new lab techniques. Some research labs return results to their participants. While research genetic testing might directly benefit participants, it might also never yield results.
Pharmacogenetic testing. For a small number of medications, the best dose of the medicine may depend on your genes. If your health care provider is thinking about giving you one of these drugs, pharmacogenetic testing may be ordered to help in decisions about what to prescribe.