If a medication is not working for you, could new testing tell you if your genes are to blame?
By | Mark Dunnenberger, PharmD, Contributor Aug. 1, 2016, at 6:00 a.m.
We all know a medication that works well for one person might not work for another – or even cause some people unwanted side effects. These differences in response can be caused by factors such as age, gender or other drugs and supplements that a person might be taking.
However, up to 99 percent of us may have small variations in our genes that can also impact how we react to common medications, including pain relievers, antidepressants and blood thinners.
Now, through a new kind of genetic testing in a field known as pharmacogenomics, some doctors are able to identify a number of these variations to help predict how their patients might respond to a new medication.
These tests are very different than genome sequencing services that provide data on your ancestry, analysis of disease-related genes or information on your risk of developing certain diseases. Instead, the tests look for specific gene variants that can help physicians minimize the trial and error of prescribing certain medications and help narrow down medication choices, especially when it comes to treatments for pain and psychiatric medications.
When I helped open the pharmacogenomics clinic at NorthShore University HealthSystem in Evanston, Illinois, in 2015, it was the first hospital-based pharmacogenomics clinic of its kind. Now, a small but increasing number of doctors and health systems are offering this testing to patients. Some direct-to-consumer testing companies also offer pharmacogenomics tests.
However, pharmacogenomics is a relatively new field, and not every doctor has access to a pharmacogenomics test or knows how to interpret the genomic information. Additionally, only about 20 percent of the drug market has been impacted by pharmacogenomics so far. For many medications, a pharmacogenomics link has not yet been found or doesn’t exist.
Understanding the basics of pharmacogenomics and how it differs from other genetic tests can help you decide whether or not these tests could be a useful tool for you and your doctor. Here’s what to know:
1. Pharmacogenomics will not tell you why your eyes are blue or predict your risk of cancer. Unlike other genetic tests, pharmacogenomics does not measure disease risk. Instead, it helps doctors identify treatments that are most likely to work by examining how your genes affect your response to medications.
2. The tests cannot give information about how you may respond to every single medication. Currently, research only supports testing for certain drugs, most commonly those for cardiology, pain management and depression/mental illness.
3. A pharmacogenomics test has value throughout your life. By studying a set of your genes, clinical experts can analyze a broad amount of information regarding drug therapy for many conditions, including psychiatric disorders, pain management and cardiology. Because your genes don’t change over time, you only need one test to discover genetic information that could be applied to future care. At some hospital-based testing centers, results can be added to your electronic medical record for easy access and used as a reference for medication and treatment choices throughout your life.
4. Pharmacogenomics is especially helpful for non-responders – people who have tried numerous drugs to find ones that effectively treat their symptoms. For some people, the tests can help explain why they didn’t respond to medications in the past, or provide peace of mind in knowing they are not genetically predisposed to a negative outcome on a new medication.
5. To make the best use of pharmacogenomics testing, have a goal in mind. Make sure that the medications covered by the genes being tested are related to your current clinical situations or medications you and your doctors are considering for future use. For example, if heart disease runs in your family, the goal of the test might be to look at the genes related to cholesterol lowering or blood thinning medications, as your doctor might consider these in your future care.
6. Pharmacogenomics is “not a crystal ball.” While it could determine why your medication isn’t working and help narrow down your options, it won’t tell you the perfect drug for your condition or provide information on drug-drug interactions or drug supplement interactions. Rather, it can narrow down your options and help doctors prescribe the right medicine faster.
7. With diagnostic tests, sometimes no news is good news. Often doctors recommend the genomic testing to rule out genetic factors as the culprit if there are concerns about medication response. No specific feedback from your genomics test means that your suboptimal response to a particular medication is not the result of your genetics, but could be caused by other factors such as diet or age.
At our pharmacogenomics clinic, testing is a two-day process that begins with a session to lay out considerations for the patient. We discuss the benefits, limitations, risks and cost so the patient can make a value-based judgment with a clear understanding of what information the test will and won’t provide.
Especially when it comes to pain medication and psychiatric medications, pharmacogenomics testing can minimize the trial and error of prescribing medications, plus help a physician to narrow down treatment choices. For some people, knowing can mean a lot. For others, it just might not be valuable for their particular situation or condition. If you think pharmacogenomics testing could help you, work with a clinician who has expertise in analyzing pharmacogenomics test results for your particular condition or who can partner with pharmacogenomics experts. This is the best way to determine whether this particular type of genetic testing is likely to provide you actionable results or peace of mind.
Mark Dunnenberger, PharmD, leads the nation’s first dedicated pharmacogenomics clinic, started last year, within the Center for Personalized Medicine at NorthShore University HealthSystem in Evanston, Illinois.