What is pharmacogenetic testing?
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.
Other names: pharmacogenomics, pharmacogenomic testing
What is it 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 health care provider 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.)
| Medicine | Genes |
|---|---|
| Warfarin: a blood thinner | CYP2C9 and VKORC1 |
| Plavix, a blood thinner | CYP2C19 |
| Antidepressants, epilepsy medicines | CYP2D6, CYPD6 CYP2C9, CYP1A2, SLC6A4, HTR2A/C |
| Tamoxifen, a treatment for breast cancer | CYPD6 |
| Antipsychotics | DRD3, CYP2D6, CYP2C19, CYP1A2 |
| Treatments for attention deficit disorder | D4D4 |
| Carbamazepine, a treatment for epilepsy | HLA-B*1502 |
| Abacavir, a treatment for HIV | HLA-B*5701 |
| Opioids | OPRM1 |
| Statins, medicines that treat high cholesterol | SLCO1B1 |
| Treatments for childhood leukaemia and certain autoimmune disorders | TMPT |
What happens during a pharmacogenetic test?
Testing is usually done on blood or saliva.
For a blood test, a health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
For a saliva test, ask your health care provider for instructions on how to provide your sample.
Will I need to do anything to prepare for the test?
You usually don’t need any special preparations for a blood test. If you are getting a saliva test, you should not eat, drink, or smoke for 30 minutes before the test.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
There is no risk to having a saliva test.
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 provider will try to find an alternate treatment.
Tests that happen before and while you’re on treatment can help your health care provider figure out the right dose.
If you have questions about your results, talk to your health care provider.
Is there anything else I need to know about pharmacogenetic testing?
Pharmacogenetic testing is only used to find out a person’s response to a specific medicine. It is not the same thing as genetic testing. Most genetic tests are used to help diagnose diseases or potential risk of disease, identify a family relationship, or identify someone in a criminal investigation.
References
- Hefti E, Blanco J. Documenting Pharmacogenomic Testing with Current Procedure Terminology (CPT) Codes, A Review of Past and Present Practices. J AHIMA [Internet]. 2016 Jan [cited 2018 Jun 1]; 87(1): 56–9. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4998735
- Lab Tests Online [Internet]. Washington D.C: American Association for Clinical Chemistry; c2001–2018. Pharmacogenetic Tests; [updated 2018 Jun 1; cited 2018 Jun 1]; [about 2 screens]. Available from: https://labtestsonline.org/tests/pharmacogenetic-tests
- Lab Tests Online [Internet]. Washington D.C: American Association for Clinical Chemistry; c2001–2018. The Universe of Genetic Testing; [updated 2017 Nov 6; cited 2018 Jun 1]; [about 2 screens]. Available from: https://labtestsonline.org/articles/genetic-testing?start=4
- Mayo Clinic: Center for Individualized Medicine [Internet]. Mayo Foundation for Medical Education and Research; c1998–2018. Drug-Gene Testing; [cited 2018 Jun 1]; [about 3 screens]. Available from: http://mayoresearch.mayo.edu/center-for-individualized-medicine/drug-gene-testing.asp
- Mayo Clinic: Center for Individualized Medicine [Internet]. Mayo Foundation for Medical Education and Research; c1998–2018. CYP2D6/Tamoxifen Pharmacogenomic Lab Test; [cited 2018 Jun 1]; [about 5 screens]. Available from: http://mayoresearch.mayo.edu/center-for-individualized-medicine/cyp2d6-tamoxifen.asp
- Mayo Clinic: Center for Individualized Medicine [Internet]. Mayo Foundation for Medical Education and Research; c1998–2018. HLA-B*1502/Carbamazepine Pharmacogenomic Lab Test; [cited 2018 Jun 1]; [about 4 screens]. Available from: http://mayoresearch.mayo.edu/center-for-individualized-medicine/hlab1502-carbamazephine.asp
- Mayo Clinic: Center for Individualized Medicine [Internet]. Mayo Foundation for Medical Education and Research; c1998–2018. HLA-B*5701/Abacavir Pharmacogenomic Lab Test; [cited 2018 Jun 1]; [about 4 screens]. Available from: http://mayoresearch.mayo.edu/center-for-individualized-medicine/hlab5701-abacavir.asp
- Mayo Clinic: Mayo Medical Laboratories [Internet]. Mayo Foundation for Medical Education and Research; c1995–2018. Test ID: PGXFP: Focused Pharmacogenomics Panel: Specimen; [cited 2018 Jun 1]; [about 3 screens]. Available from: https://www.mayomedicallaboratories.com/test-catalog/Specimen/65566
- National Cancer Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; NCI Dictionary of Cancer Terms: gene; [cited 2018 Jun 1]; [about 3 screens]. Available from: https://www.cancer.gov/publications/dictionaries/cancer-terms/search?contains=false&q;=gene
- National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests; [cited 2018 Jun 1]; [about 3 screens]. Available from: https://www.nhlbi.nih.gov/health-topics/blood-tests
- NIH National Institute of General Medical Sciences [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Pharmacogenomics; [updated 2017 Oct; cited 2018 Jun 1]; [about 4 screens]. Available from: https://www.nigms.nih.gov/education/Pages/factsheet-pharmacogenomics.aspx
- NIH U.S. National Library of Medicine: Genetics Home Reference [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; What is pharmacogenomics?; 2018 May 29 [cited 2018 Jun 1]; [about 4 screens]. Available from: https://ghr.nlm.nih.gov/primer/genomicresearch/pharmacogenomics
- UF Health: University of Florida Health [Internet]. University of Florida; c2018. How your genes influence what medicines are right for you; 2016 Jan 11 [updated 2018 Jun 1; cited 2018 Jun 1]; [about 2 screens]. Available from: https://ufhealth.org/blog/how-your-genes-influence-what-medicines-are-right-you
- UW Health American Family Children’s Hospital [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2018. Kids Health: Pharmacogenomics; [cited 2018 Jun 1]; [about 4 screens]. Available from: https://www.uwhealthkids.org/kidshealth/en/parents/pharmacogenomics.html/
