Clinical Genetic Testing
Does this test have other names?
Genetic screening, DNA test or testing, chromosomal test, gene testing, DNA-based test
What is this test?
Genetic testing is usually done to screen newborns, children, or adults for inherited diseases or genes that put them at increased risk for a certain disease. Some parents choose to be screened before or during pregnancy to see whether they are carriers of a certain disease, such as hemophilia.
Your genes are like a road map: They hold the blueprint for all of your inherited traits, from the color of your eyes to how tall you will grow.
But your genes can also tell you whether you're at risk of inheriting a disease, such as breast cancer, cystic fibrosis or Huntington disease. They can even help tell your doctor how to tailor the right medicines for your condition.
A genetics test can find out whether you have damaged, missing, or overactive genes that can cause certain diseases. This test scans the pattern of your genes, or DNA, in your blood or other fluids, such as saliva or urine.
These are types of genetic testing:
Gene tests, which examine individual genes or fairly short strands of DNA or RNA
Chromosomal tests, which test entire chromosomes or long strands of DNA
Biochemical tests, which look at protein and enzyme activities
Why do I need this test?
You may have this test, even if you don't have symptoms, if your doctor suspects you have inherited a certain condition. This test can also find out whether your biological child might have inherited a disorder from you or the other biological parent.
If you belong to an ethnic or other group in which a certain inherited disease is more common, your doctor may order a test to help determine your risk. Your doctor may also order a test if you have a disease that runs in your family.
Genetic testing is used in the following ways:
To help your doctor find out the cause of your disease or disorder
To find out whether you are a carrier of a gene for a disease before or after you have symptoms
To aid parents in finding out whether an unborn child has a gene for a disease
To help parents find out whether their newborn baby has a damaged gene that can cause a disease
To help determine your risk for a certain disease
To help your doctor find out which medicine or therapy might be best for you
Genetic testing can ease your mind about your or your child's inherited risk for a certain disease if you get a negative result. Finding out you are predisposed to developing a certain disease could lead to your getting more regular screenings or making lifestyle changes to help prevent the disease. Even learning that you have an inherited disease, painful as the news may be, can help you plan treatment and take other important steps. In some cases, though, positive findings might force you to make some unwelcome choices, so it is your right to choose or turn down genetic testing.
What other tests might I have along with this test?
If you or your newborn has symptoms of a particular disease, your doctor will likely run specific tests for that disease.
Before you go through any genetic test, your doctor will ask you to get pre-test counseling so that you can understand what the test involves, how accurate it is, how you will get the results, and how results will be shared with your healthcare provider. You may also want to ask about emotional and psychological support.
What do my test results mean?
Many things may affect your lab test results. These include the method each lab uses to do the test. Even if your test results are different from the normal value, you may not have a problem. To learn what the results mean for you, talk with your healthcare provider.
If your doctor is looking for a particular gene, your results will be either negative or positive for that gene. Even if you were born with a gene that puts you at risk for a disease, it doesn't necessarily mean you will ever have it.
The findings from a genetic test may not be simple to understand. Your doctor may refer you to a genetic counselor, who can represent your interests and help translate the results for you.
Genetic counselors can help you understand the science behind genetic testing and the emotional response you may have to the findings. They can also help research your family history and look at your medical records.
How is this test done?
This test can be done on samples of your skin, blood, hair, urine, or other tissues. You might be asked to give a blood sample or a swab from the inside of your mouth.
Does this test pose any risks?
Taking a blood sample with a needle carries risks that include bleeding, infection, bruising, or feeling dizzy. When the needle pricks your arm, you may feel a slight stinging sensation or pain. Afterward, the site may be slightly sore.
Although this test poses no major physical risks, it can affect your emotions, your job, and even your healthcare coverage. The Genetic Information Nondiscrimination Act was passed in 2008 to protect insurers and employers from using the results of genetic testing to drop your healthcare coverage or to fire you.
Consumers can get genetic testing done with kits that are available on the Internet. This can be a risky move, however. Different laboratories can have results that are difficult to understand, and the results can vary. Doctors caution against getting tested without speaking with a genetic counselor first.
Because of the emotional impact of genetic testing, you may want to consider how you will feel if you find out that you or someone you love has a gene that can cause a physical disorder or disease. This may be especially true for a disease such as Alzheimer's, which has no known prevention or cure.
What might affect my test results?
Different kinds of genetic tests yield different information, and results may vary by laboratory. Your results are based on a test of your genes, so lifestyle choices will not affect the findings.
How do I get ready for this test?
You don't need to prepare for this test.
- Hanrahan, John, MD
- Taylor, Wanda, RN, Ph.D.