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About pharmacogenetics


Pharmacogenetics (pronounced FAR mah coh je NEH tiks) is the study of how your genes affect the medicines you take. Your genes decide how your body responds to a medicine. For example, knowing about your child’s genes can tell the doctor:

  • Which medicine is likely to work best for your child’s illness, or
  • How likely your child is to have a side effect from a medicine.

About your genes

Your body has a set of instructions that tell it how to work. These instructions are called “DNA.” The DNA contains bits of information called “genes.” Each gene is part of your body’s instructions, and your genes are different from everyone else’s. So learning about your genes helps doctors know how your body works.

Testing for specific genes is called “genetic testing.” Testing to learn how genes work with certain medicines is called “pharmacogenetic testing.” The test results can help doctors choose the best medicine and dose for your child.

Pharmacogenetic testing for your child

Pharmacogenetic testing can be done in several ways. At St. Jude, the test is done through a blood test. Doctors can test genes in different ways:

  • One gene at a time: This method is used when the doctor knows your child will need a certain medicine that is affected by that gene.
  • Many genes at a time: This method tests for several genes that can affect medicines. This is usually done before your child’s doctors expect to use medicines that might be affected by your genes. The pharmacogenetic test result will be in your child’s medical record for your doctor to use when needed.

How long do my child’s test results last?

Your child’s pharmacogenetic test results last a lifetime, because genes will not change over time. So doctors can always use the results. This can help doctors pick the best medicines for your child in the future.

Save any pharmacogenetic test results you get from St. Jude. Tell your child’s other doctors that pharmacogenetic testing has been performed on your child and inform them of the results.

What if doctors learn more about genes later?

Your child could have more pharmacogenetic tests done in the future. Scientists are always finding new genes that affect how medicines work, so there could be new genes to test for in the future.


If you have questions about pharmacogenetic testing at St. Jude, call one of the Pharmaceutical Sciences research nurses at 901-595-2482 or email If you are calling from outside of the Memphis area, dial toll free 1-866-2ST-JUDE (1-866-278-5833), then dial extension 2482. Or visit for more information.


This document is not intended to take the place of the care and attention of your personal physician or other professional medical services. Our aim is to promote active participation in your care and treatment by providing information and education. Questions about individual health concerns or specific treatment options should be discussed with your physician.

St. Jude complies with health care-related federal civil rights laws and does not discriminate on the basis of race, color, national origin, age, disability, or sex.

ATTENTION: If you speak another language, assistance services, free of charge, are available to you. Call 1-866-278-5833 (TTY: 1-901-595-1040).

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