By Ginevra Liptan, MD
Someday in the not-so-distant future, before your health care provider decides which medication to prescribe for your fibromyalgia symptoms, they might first swab your cheek for a few cells and send them off for genetic tests. The genetic data hidden in those cells might reveal which medications you are likely to get benefit from, and which to avoid due to higher chance of side effects.
It sounds futuristic, but in fact this technology is available now, though it has not been widely adopted by medical providers. Testing for a person’s gene-drug interactions is called “pharmacogenetics,” and is a rapidly expanding field with multiple companies now offering panels of tests targeted to different illnesses.
Certainly genes don’t tell the whole story, and how we respond individually to a medication depends on multiple other factors in our environment. But we have long known that genetic makeup plays an important part in how we respond to different medications. Health care providers often see that our patients are likely experience a similar response to medications—good or bad—as their family members.
Using family members’ response to guide our prescribing is not very scientific. It would be far better to obtain specific, personalized genetic information for a patient prior to prescribing any medication. It would give us a head start to choosing the right medication, and shorten the painful trial-and-error process that we otherwise go through before finding effective treatments.
Having this head start could be especially valuable in fibromyalgia, as we tend to be extra sensitive to medications and more prone to side effects. So I was excited to learn that the first genetic testing panel devoted specifically to fibromyalgia was just released by Proove Biosciences in June 2016. In addition to testing for genes related to processing of typical fibromyalgia medications, they went one step further. According to Ashley Brenton, Ph.D., associate director of research and development at Proove, their test also assesses abnormalities in 11 genes that influence pain-processing and that affect your likelihood to develop fibromyalgia.
We already know that there is some genetic predisposition to developing fibromyalgia, from the simple fact that it tends to run in families, just like diabetes and many other chronic illnesses. But there is not one specific fibromyalgia gene. Rather there seem to be multiple genes that play a part in setting the stage for fibromyalgia, and the Proove fibromyalgia panel tests for the well studied of these genes. Primarily these are the genes that affect how well the brain makes and process certain chemicals like serotonin and norepinephrine, which are very important to regulating pain levels.
Dr. Brenton tells me they are also actively doing research on the genetic samples they collect. This type of research might help to discover new information about how to diagnose and treat fibromyalgia.
While seeing what your genes might reveal about pain-processing is fascinating, the component of the Proove fibromyalgia panel addressing specific gene-drug interactions is more practically useful. These gene-drug interactions come down to two factors: First is pharmacokinetics, or what your body does to the drug. The second is pharmacodynamics, or what the drug does to your body. These factors predict which drugs are most likely to be effective, which might cause side affects, and which might require close monitoring or dosage adjustments.
Let me give you some real-life examples from my practice (not their real names): “David” is in his 50s and has fibromyalgia and severe depression. Over the years he had tried, and failed miserably, all antidepressants that act by boosting serotonin levels in the brain, called SSRIs. His pharmacogenetic testing showed that he was a “poor responder” to that entire class of medication, but was likely to respond well to a different, less commonly used, type of medicine. And indeed he did.
The gene that showed up on David’s testing is one that affects how well our brains recycle serotonin, an important brain chemical associated with depression. Every human has this gene, but some of us have the long version, and some of us have the short version. Scientists have found that those that have the long version of this gene tend to respond well to SSRI medications with few side effects, but those that have the short version tend to find less benefit and more side effects. This is an example of a genetic difference affecting how a drug affects your body (pharmacodynamics).
Now let’s talk about another patient of mine, “Mary,” a very petite woman with a big personality who tells me that she requires “horse tranquilizers” to keep her asleep during surgery. She always warns the anesthesiologist that she will need high doses of medications to avoid waking up during surgery. This is because her body rapidly gets rid of that type of medication, and is a perfect example of how your body affects a drug (pharmacokinetics).
We all vary in how quickly our body gets rid of medications. This is determined by the genetic makeup of our liver enzymes that process medications. Because we know which drugs are processed by which enzymes, genetic testing can predict who might need dosage alteration of certain medications. There are several opiates that vary dramatically in how well they are processed by the body, including codeine, oxycodone, and tramadol. Having this information beforehand could vastly improve the process of finding the most effective, and safest, dosage of pain medications.
The science of gene-drug interactions is still young. This type of testing is expensive, but more insurance companies are starting to see the benefit and pay for certain types of pharmacogenetic testing. The Proove fibromyalgia profile is quite new, and many doctors and insurance companies are not familiar with it yet. If you want to learn more about this testing yourself, go to http://www.proove.com. Other companies that do non-fibromyalgia specific gene-drug testing include Genomind (Genomind.com), PGXL laboratories (pgxlab.com), and Rxight (rxight.com).