Genetic Pharmacology Service

  • Frequently Asked Questions

    We know you may have questions. That’s why the Genetic Pharmacology Service for children and adults provides answers to frequent questions about pharmacogenetic testing.

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    + Why is a pharmacogenetic (PG) test done?

    A pharmacogenetic (PG) test can be done before or after a medicine is given.

    Before a medicine is given: A PG test may help your doctor choose the medicine and dose that will work best for you.

    After a medicine is given: A PG test may help the doctor understand why you are having problems with a medicine. The test may also help the doctor decide if a different dose or different medicine should be tried.

    + Is PG testing required?

    Most PG tests are optional.  A few medicines are designed for people with certain cancers or infectious diseases.  A PG test of a tumor or a person’s blood may be needed to know if a medicine will work.  Most times, you can be treated with standard medicine doses without this gene testing.  Make sure you understand why your doctor is recommending a PG test for you.

    + What is being tested with a PG test?

    A small sample of blood or scrapings from the inside of your cheek is analyzed for specific genes that can influence a person’s response to a medicine.

    + What are genes?

    Genes are pieces of DNA that we inherit from our parents.  Genes provide the instructions to make our bodies look and work as they do.

    + What do genes have to do with medicines?

    Some genes affect the way medicines work in the body. When comparing a group of people, there can be slight differences in each gene’s structure. These differences can affect how people react to medicine.

    1. Some gene differences might make it harder for the body to get rid of some medicines. This means that the usual doses of such medicines could give some people unexpected side effects.
    2. Some gene differences can cause the body to use up a medicine too fast. This means that normal doses won’t work as  well and the person may need higher doses. 
    3. Some gene differences won’t let certain medicines work in the body at all.  This means that a different medicine may work better. 

    + How will the PG test help me?

    • The test may improve the chances that the medicine will help you as intended.
    • The test may lower the chance of severe side effects from the medicine.
    • The PG test for the medicine may only need to be done once in a lifetime. The test looks at common gene differences. If the common gene differences are found in your blood, then the test will not need to be repeated.
    • The gene tested today may be important for medicines that you need in the future.

    + Does the PG test have any limitations?

    • The test looks only at common gene differences. This means if the test does not find any of the common gene differences, you could still have one or more rare gene differences. The test will not detect rare gene differences. Some of these rare differences might affect how you react to the medicine.
    • Gene differences are one of many factors that can affect how you react to medicine. A few examples of other factors are your age, weight, other medicines and illnesses.  Your doctor will need to consider these factors along with the PG test results.

    + Is there anything else I should know about the PG test?

    In the future, some of these common gene differences may be found to be associated with other medical conditions.

    The test results may be important for other family members. Biologic brothers, sisters and parents may have one or more of the same tested genes in common. 

    + How much does the PG test cost?

    The cost of the PG test depends on many factors. Insurance companies usually cover the costs of genetic tests that are used to guide medical management. Insurance companies vary in their coverage policies.  It is wise to ask them directly whether they will cover the cost of PG testing.

    + How long does it take to get the test results?

    Test results on a blood sample will be ready in two business days.  Test results on a sample of cheek scrapings may take up to four business days.

    + How will I learn about my test results?

    The doctor or nurse will discuss the test results with you.  The doctor will receive a report from the laboratory.  The report will describe how your doctor can adjust your medicine based on your test results.

    + Will my gene result be in the medical records?

    Yes. Cincinnati Children’s strictly follows HIPAA guidelines to protect medical information.

    + What will happen to my sample?

    Your DNA from your sample may be stored for up to two years in case future tests are needed. Neither your sample nor DNA will be used for research purposes.

    + Will I receive any type of handout or educational material?

    Patients and parents of pediatric patients should be given a choice of whether to have a pharmacogenetic test. Download a handout to help you decide whether to have testing by providing answers to frequently asked questions.