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Your Genes & Your Medications

Pharmacogenetics, also called pharmacogenomics, is the study of how genes affect the body’s response to certain medicines. Genes are parts of DNA passed down from your mother and father. They carry information that determines your unique traits, such as height and eye color. Your genes can also affect how safe and effective a particular drug could be for you.

Genes can be the reason the same medicine at the same dose will affect people in very different ways. Genes may also be the reason some people have bad side effects to a medicine, while others have none. Pharmacogenetic testing looks at specific genes to help figure out the types of medicines and dosages that may be right for you.

What is Pharmacogenetic Testing used for?

Pharmacogenetic testing may be used to:

  • Find out whether a certain medicine could be effective for you
  • Find out what the best dosage might be for you
  • Predict whether you will have a serious side effect from a medicine

Why do I need pharmacogenetic testing?

Your doctor may order these tests before you start a certain medicine, or if you are taking a medicine that is not working and/or causing bad side effects.

Pharmacogenetic tests are only available for a limited number of medicines. Below are some of the medicines and genes that can be tested. (Gene names are usually given in letters and numbers.)

What happens during a pharmacogenetic test?

MyRx uses a simple swab to collect cheek cells containing a sample of your DNA. We will provide instructions on how to provide your sample.

What do the results mean?

If you were tested before starting a treatment, the test can show whether a medicine will likely be effective and/or if you are at risk for serious side effects. Some tests, such as the ones for certain drugs that treat epilepsy and HIV, can show whether you are at risk for life-threatening side effects. If so, your doctor will try to find an alternate treatment.

Tests that happen before and while you’re on treatment can help your doctor figure out the right dose.

If you have questions about your results, talk to your doctor

How Do Genes Affect Medication Response?

Tiny differences in your DNA can have a huge impact on your body and how it works. On the outside, your DNA determines how you look, like your eye color or your height. On the inside, DNA provides a recipe for all your organs and tissues, like your heart, lungs and muscles, even the smallest proteins or enzymes that your body makes. These proteins and enzymes determine how your body works.

Some proteins in the liver, such as those called the CYP450 enzymes, are very important in predicting how your body will respond to a medication. Tiny differences in your DNA can cause you to have too much, or too little, liver enzyme activity. This can result in a medication not working as well or a higher chance of side effects.

In most people, liver enzymes work just as we would expect, leading to a normal medication response. Based on genetic test results, we can more precisely determine how you respond to a medication and decide if you need a higher or lower dose, or a different medication.

We will consult with your doctors if we have any recommended changes to your medications.

Which medications are impacted by pharmacogenetics?*

*Not a comprehensive list