What Is Genetic Testing?

Genetic testing is used to examine DNA, the chemical database that holds the instructions for the body’s functions. Genetic testing assesses for gene mutations that may cause disease or illness. Testing allows for early diagnosis, treatment, or for preventative measures to be taken. Although genetic testing can be helpful, it is important to note that genetic testing has limitations, in that a positive result does not necessarily mean a healthy person will develop a disease. Similarly, a negative result does not guarantee you will not develop a certain disease or disorder.

Genetic testing can identify variations, mutations, or abnormalities in genes, chromosomes, and proteins. There are several reasons people seek out genetic testing. Speaking with a genetic counselor can help you determine if genetic testing is right for you.

Common reasons may include:

• To identify, before symptom onset, if you have a genetic condition that runs in your family
• To find out if your child may be born with a genetic condition
• To get a diagnosis for a genetic condition for which you or your child have symptoms
• To gain insight, understanding and guidance for cancer treatment or cancer prevention

Types of Genetic Testing

There are several types of genetic testing. Determining which tests are administered is dependent on your family medical history and the specific condition for which you are being tested. It is important to consult with a genetic counselor to better understand the reason you are seeking genetic counseling and to understand which tests might be most beneficial. The types of genetic testing include:

Diagnostic Testing

This type of testing is used when current symptoms may indicate a certain genetic condition or gene mutation or abnormality. Diagnostic testing can determine whether you have the suspected condition. Some examples of this type of testing would be checking for Huntington’s disease or cystic fibrosis.

Carrier Screening

Carrier screening is utilized when you have a family history of a genetic condition, such as cystic fibrosis or sickle cell anemia. This type of testing may also be used when you are part of an ethnic group that is at a higher risk for having certain genetic disorders. Some people choose to do carrier screening before having children, to determine if there is a greater risk for their child to have a genetic disorder.

Prenatal Testing

This type of testing can identify any abnormalities in your unborn child’s genes. Often, prenatal testing will assess for Down syndrome and trisomy 18 syndrome. This can be done through blood tests, or by a more invasive test, known as amniocentesis. There is also a newer test, known as cell-free DNA testing, that can assess the baby’s DNA through a blood test from the mother.

Predisposition Testing

This type of testing is utilized if you have a family history of a certain genetic condition. Predisposition testing happens before you have any symptoms, and it can determine if you are at risk for developing a specific genetic condition. For example, you may want to screen for colorectal cancer if it runs in your family.

How is Genetic Testing Done?

There are several methods for administering genetic testing. Usually testing requires a sample of blood, amniotic fluid, skin, or other tissue to be sent to a lab for assessment. The most common methods include:

• Blood sample. This test is administered by inserting a needle into the arm and collecting a sample to be sent to a lab for assessment. Screening tests for newborns require the needle to be inserted into the baby’s heel.
• Cheek swab. This test takes a sample of saliva by swabbing the inside of the mouth.
• Amniocentesis. This is a prenatal genetic test where a thin hollow needle is inserted through the abdominal wall into the uterus to collect a sample of amniotic fluid. The sample is then sent to a lab for testing.
• Chorionic villus sampling. This is a prenatal genetic test that takes a sample of tissue from the placenta. The test can be administered by inserting a tube through the cervix or by inserting a thin needle into the abdominal wall and uterus.

Understanding Your Results

The amount of time it takes to get results from genetic testing can vary, depending on the test and number of tests taken. Consult with your doctor, geneticist or genetic counselor to discuss the timeline of the results and to gain a better understanding once you have the results.

When you receive your results, you will either be given a positive, negative or variants of unknown significance (VUS) result. A positive result means that the genetic change or abnormality that was being tested for has been detected. A negative result means that an abnormal gene was not detected. However, it does not mean with 100% certainty that you will not develop the disorder. The accuracy of genetic tests can vary. A result of variants of unknown significance means there were gene variations detected, but it cannot be determined if the variations are harmful or not.

It is important to consult with your doctor, geneticist or genetic counselor to go over the results and ask any questions you may have regarding the results and next steps forward.

Considerations before Genetic Testing

If you are considering genetic testing, it is important to gather all family medical history, specific to the condition for which you want testing. You may also want to consider what and how you plan to communicate with your family about your genetic testing, especially if it is a genetic condition that runs in the family. Speak with a genetic counselor to discuss any concerns, potential risks of testing or questions you may have.

Not every insurance provider covers genetic testing, so make sure to find out from your provider whether they cover this type of testing. It is also important to remember that because of the federal Genetic Information Nondiscrimination ACT (GINA), neither health insurance companies nor employers can discriminate against you based on the test results or having a genetic risk.

Learn More about Genetic Testing

Genetic testing can be critical for early detection, which can allow for prevention measures or early treatment approaches to be implemented. Genetic testing can greatly improve treatment outcomes by giving you and your healthcare provider team a head start in the treatment process. Make sure to consult with your genetic counselor or geneticist as you begin the process of testing.

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