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When you take a medicine, your body needs a way to handle it. One way your body does this is by using enzymes to break down (metabolize) the medicine. A family of enzymes called cytochrome P450 breaks down certain medicines. The enzymes make the medicine more or less active, depending on the specific medicine.
Cytochrome P450 3A5 enzymes, known as CYP3A5, break down some medicines, including medicines used after a bone marrow or solid organ transplant.
Each person differs from another at the DNA level. Genes are segments of DNA that act as a set of instructions and tell the body how to work. The CYP3A5 gene is a section of DNA that instructs how well CYP3A5 enzymes will work.
The study of how genes like CYP3A5 affect the way your body interacts with medicines is called pharmacogenomics. Differences in your DNA that make up the CYP3A5 gene can affect how well you are able to break down certain medicines.
A pharmacogenomic test looks for differences that can help your medical team know how well your CYP3A5 enzyme will work. The test results can help your doctor and pharmacist choose the correct dose of medicine to give you.
The results of your CYP3A5 test will place you into one of three groups:
Scientists continue to find new information about which medicines are affected by gene test results. Talk to your doctor or pharmacist if you have questions about your medicines, side effects, or pharmacogenomic testing.
If you have questions about pharmacogenomic testing done at St. Jude, you can email the Clinical Pharmacogenomics Program at firstname.lastname@example.org.
Reviewed: September 2022