Overview
Genetic testing looks at DNA. DNA is the set of instructions for how the body works. Genetic testing can show DNA changes in genes that may affect health. Healthcare professionals also can use genetic testing to choose treatments or see how well treatments might work.
Genetic testing can give important information for screening, diagnosing and treating health conditions, but it has limits. For example:
- A positive result doesn't always mean that you'll get the condition.
- A negative result doesn't always mean that you won't get the condition.
Talk with your healthcare professional, a medical geneticist or a genetic counselor before and after genetic testing to understand what the results mean for you.
Whole genome sequencing
When genetic testing is negative, or the results aren't clear but a genetic cause is still suspected, some facilities offer more testing, such as whole genome sequencing.
Everyone has a unique genome, made up of the DNA in all of a person's genes. Whole genome sequencing is a process for analyzing a sample of DNA. A sample is taken from blood or other sources such as saliva, a cheek swab or cells from the skin.
This complex testing can help identify genetic differences that may affect your health.
Products & Services
Why it's done
Genetic testing can look at the risk of getting certain health conditions. Testing also can be used for screening, diagnosis and sometimes planning for medical treatment. Different types of genetic testing include:
- Diagnostic testing. When symptoms could be related to a condition caused by gene changes, genetic testing can help diagnose the suspected condition. For example, genetic testing can confirm a diagnosis of cystic fibrosis or Huntington's disease.
- Predictive testing. If you have a family history of a genetic condition, genetic testing before you have symptoms may show if you're at risk of getting the condition. For example, predictive genetic testing may show your risk of certain types of colorectal cancer.
- Carrier testing. You might choose to have genetic testing before having children if there is a history of an inherited condition or if you want to know your risk of certain hereditary diseases. This testing can show if you carry certain gene changes and could pass on a condition to your children. For example, you may have carrier testing if your family has a history of cystic fibrosis or if you're in an ethnic group that has a high risk of a specific genetic condition, such as sickle cell anemia. Carrier testing also can tell if you and your partner both have gene changes for the same health conditions. An expanded carrier screening test can find genes linked with a wide variety of genetic conditions.
Prenatal screening tests and diagnostic tests. Screening tests during pregnancy can show what the chances are that a baby has gene changes. Some prenatal screening tests look at genetic markers in a pregnant person's blood. The prenatal cell-free DNA screening test uses a blood sample from the pregnant person to look at the baby's DNA to help estimate the risk of Down syndrome and trisomy 18 syndrome, for example.
Prenatal diagnostic tests can tell if a baby has certain genetic conditions. Diagnostic tests such as amniocentesis or chorionic villus take a sample of amniotic fluid from around the baby or tissue from the placenta to detect a genetic condition.
- Newborn screening. In the United States, all states require that newborns be tested for some genetic and metabolic changes that cause specific health conditions. Newborn screening can find conditions early so that treatment can begin right away to prevent complications. For example, newborn screening can suggest the presence of sickle cell anemia and phenylketonuria, also called PKU.
- Preimplantation testing. Also called preimplantation genetic diagnosis, this test may be used when trying to conceive a child through in vitro fertilization, also known as IVF. The embryos are screened for some genetic changes or a known genetic condition in the family before they're implanted in the uterus.
- Pharmacogenetic testing. Also called pharmacogenomic testing, this genetic testing may help decide on the best medicine and dose for you. This type of testing is not routine. Ask your healthcare professional for more information.
Consumer genetic testing
You can buy consumer genetic tests without a prescription and send in a sample of saliva from your home. These also are called direct-to-consumer (DTC) genetic tests. Typically, you spit into a tube and send the sample to a company for testing. You may get your results in a letter or by visiting a webpage that's protected by a password. The tests can tell you about your family history. Some tests give health-related information, but it may not be accurate. Clinical genetic testing by healthcare professionals is more accurate.
It's not always clear what DTC genetic tests say about your health. Many factors specific to you may not be part of the results. The tests don't always give clear answers about your health and shouldn't be used to make medical decisions.
Before you use a DTC genetic test, check:
- What kind of results you'll get.
- How accurate the test is.
- What happens to your DNA sample.
- The company's privacy policy.
Talk with your healthcare professional or a medical geneticist or genetic counselor about the best genetic tests for you. These professionals also can help you understand the results.
More Information
Risks
Most genetic tests are generally safe. Blood and cheek swab tests have almost no risk. Some prenatal tests, such as amniocentesis or chorionic villus sampling, have a small risk of pregnancy loss, also called a miscarriage.
Genetic testing can have emotional, social and financial risks. Talk with your healthcare professional about the risks and benefits of genetic testing. A medical geneticist or a genetic counselor can talk with you about what to expect from testing and what the results mean for you and your family.
How you prepare
Before you have genetic testing, talk with your healthcare professional or a medical geneticist or genetic counselor. It's also helpful to:
- Learn about your family's health history.
- Talk with your family. Test results may affect your family, too.
- Bring information about your personal and family history.
- Ask questions about genetic testing.
- Talk about what the test results may mean for you.
- Find out if your insurance covers the cost of testing. Genetics clinics or some labs often can give you this information.
In the United States, the Genetic Information Nondiscrimination Act (GINA) protects you from discrimination by health insurers or employers based on genetic test results. But it doesn't cover life insurance, long-term care insurance or disability insurance. Some states offer more protection than GINA does.
What you can expect
Depending on the type of test, a sample is taken and looked at in a lab.
- Blood sample. A member of your healthcare team takes blood from a vein in your arm. For newborn screening tests, a blood sample is taken by pricking the baby's heel.
- Saliva. You spit saliva into a collection tube.
- Cheek swab. Using a cotton swab, a member of your care team takes a sample of cells by rubbing the inside of your cheek.
- Amniocentesis. In this prenatal genetic test, a healthcare professional passes a thin hollow needle through your belly wall and into your uterus. A small amount of fluid around the baby, called amniotic fluid, is taken for testing.
- Chorionic villus sampling. For this prenatal genetic test, a health professional takes a small sample of tissue from your placenta. The sample may be taken by passing a small tube through your cervix or by passing a thin needle through your belly wall.
Results
The amount of time it takes for you to get your genetic test results depends on the type of test and your healthcare facility. Ask your healthcare professional when you'll get the results.
Positive results
If the genetic test result is positive, that means the genetic change that was being tested for was found. What comes next depends on the reason you had genetic testing.
- Screen for a condition. A positive result may suggest the condition is present, but you may need more testing to confirm the diagnosis.
- Diagnose a specific condition. A positive result helps you and your healthcare team decide on the right management plan.
- Find out if you have a gene change that could be passed on to your children. A positive result can help you and your healthcare professionals talk about your child's risk of getting the condition. The test results also can give you information to help make family planning decisions.
- Find out if you might get a certain condition. A positive test may mean that you're at high risk of getting a specific condition. But this does not always mean that you'll get that condition. For example, having a breast cancer gene, such as BRCA1 or BRCA2, means you're at high risk of getting breast, ovarian and other cancers. It doesn't mean for sure that you'll get cancer. With some conditions, such as Huntington's disease, having the changed gene does mean that the condition will develop over time.
Talk with your healthcare professional about what a positive result means for you. In some cases, you can make lifestyle changes that may lower your risk of getting a condition. This may be true even if you have a gene that makes you more likely to get it. Results also may help you make choices about treatment, family planning, careers and insurance coverage.
You may choose to be part of research or registries that are general or related to your genetic condition. These options may help you stay updated with new developments in prevention, management or treatment.
Negative results
A negative result means that the test did not find a changed gene or genes. This can be good news, but it's not a 100 percent guarantee that you're not at higher risk of developing a condition based on your genes. The accuracy of genetic tests to find changed genes may vary based on the current knowledge and testing methods.
Not having the changed gene doesn't mean you'll never get the condition. For example, most people who get breast cancer don't have any of the currently known breast cancer genes.
Results that aren't clear
Sometimes a genetic test doesn't give helpful information about the gene being tested. Genes may look different, but often these differences don't affect health. Sometimes it can be hard to tell the difference between a gene change that can cause a condition and a gene change that doesn't affect health. When the effect of a gene change on health is not well understood, it's called a variant of uncertain significance. When this happens, typically you don't need to do anything, unless a link with a health condition becomes clearer over time.
Genetic counseling
No matter what the results of your genetic testing are, talk with your healthcare professional, medical geneticist or genetic counselor. This helps you understand the results and what they mean for you and your family.
Clinical trials
Explore Mayo Clinic studies of tests and procedures to help prevent, detect, treat or manage conditions.
Feb. 27, 2026