Pain and Genetics

With all the research being done in genetics, is there an application for pain sufferers?

The short answer is yes – in pain sensitivity, prediction for chronic pain conditions and even determining which medication may be more beneficial in reducing pain. The long answer is that much of the research thus far is inconclusive and there is still a lot of work to be done before physicians can truly begin using a patient’s genetic makeup as part of their pain treatment plan. In between, there are specific answers to aspects of pain genomics of interest to pain sufferers.

Let’s start with what we know so far.

Can genes indicate your pain tolerance or pain sensitivity?

Researchers believe that there is a link between an individual’s genes and the way they feel pain – how tolerant or sensitive they are to it. Dr. Richard Rauck, editor-in-chief of PainPathways Magazine and physician with the Carolina Pain Institute, provides some insights on this topic.

“We are just beginning to understand some of this. We know, for example, that certain people have a genetic mutation that makes them feel no pain. This is not good for survival. This includes the group of people in the far east who can “walk on coals” without feeling pain.”

Dr. Rauck believes that pain genomics is a somewhat elusive field still. It has proven as helpful, for instance, as in what science has seen in genetics and cancer.  However, he thinks the future for pain genomics is very exciting.

A major study in 2014 evaluated 2,721 diagnosed with chronic pain. Participants were talking opioid pain medications. Researchers looked at specific genes within the participant group: COMT, DRD2, DRD1 and OPRK1. They also asked each participant to rate their pain perception on a scale of zero to ten. Based on the rating, participants were considered low pain, moderate pain or high pain perception.

The results show that certain gene variants were more prevalent in each of the three pain groups:

• DRD1 was more prevalent in the low pain group.
• COMT and OPRK were more prevalent in the moderate pain group.
• DRD2 was more prevalent in the high pain group.

“Our study is quite significant because it provides an objective way to understand pain and why different individuals have different pain tolerance levels,” said study author Tobore Onojjighofia, MD, MPH, with Proove Biosciences and a member of the American Academy of Neurology. “Identifying whether a person has these four genes could help doctors better understand a patient’s perception of pain.”

So what can healthcare professionals take from what research has shown thus far?

For starters, they can stop looking at all patients as the same when it comes to pain responses. Differences in pain tolerance and response to pain medications are at least partly connected to a patient’s genetic makeup. These connections could be significant – and without considering them, physicians could end up under or over treating patients. The challenge today is that it is uncommon for a physician to know anything about a patient’s genetic makeup. Genes, prior experience, physiological status, expectations, mood, pain-coping skills and sociocultural background can all have an impact on one person’s pain tolerance.

However, one point is clear: genes or heritability is apparently more significant than previously thought. With the continuation of research and many more data points, the degree to which genetics contribute will become clear. Scientists and physicians alike anticipate that one day, pain genomics will lead to more specific treatment plans – tailored for the genetic makeup of an individual.

Can genetics improve medication recommendations?

Today, there are no uniformly accepted practices for using genetics to better match a pain medication to a pain sufferer. There are genetic testing companies out there that believe they have an approach for this. Physicians like Dr. Rauck are hopeful but not convinced yet.

“I don’t think we are there yet. Maybe, in 5-10 years. Some people have used the genetic knowledge about enzymatic metabolism to help understand if patients are rapid metabolizers or slow metabolizers of certain pharmaceutical drugs. I don’t find it really helpful but others tout it…and some companies do mouth swabs to get this information,” said Dr. Rauck.

It’s evident that a medication that works for one person may not do much for another, given the variability in an individual’s physiology. There are still too many unknowns with that variability. Some hope genetics will help answer treatment questions by using a blood test that detects the genetic variants a person carries. The benefit of this personalized approach would be to shorten the trial-and-error many patients go through as they seek effective treatments. But most physicians feel that science has not arrived at this point yet.

Can genetics predict if you will have certain pain conditions?

While the field of pain genomics is still in its infancy, genetics, in general, has already shown promise in helping physicians predict conditions. One good example is with cystic fibrosis. Genetic testing can be used to tell if a person carries the defective CF gene or the gene that may predict cystic fibrosis in a couple’s child. With cancer, genetics can indicate markers or possible predictors of cancer. Here, the genetics is pretty good but not conclusive. Markers only really account for 30% of the patients who end up with cancer.

During the last 20 years, studies have made considerable strides toward identifying key genetic indicators of the onset and experience of chronic pain. Studies of people with back pain have indicated that some genetic variations impact patients’ long-term pain recovery. There have been studies about genetics and migraine pain, musculoskeletal pain and postoperative pain…just to name a few.

Again, the studies show promise and provide directional insights. But the conclusive evidence that would allow physicians to successfully modify treatment based on genetics is not there – yet.

Can you override your bad pain genes? 

Epigenetics are biological mechanisms that will switch genes on and off. Environment, lifestyle, what you eat, where you live, how you sleep, even aging can cause genes to be silenced or “expressed” over time. Each of these is an example of epigenetics.

RELATED: You are what you eat: How food can effect pain

Epigenetics creates so many variables that genetics work is a challenge for researchers. The different combinations of genes and environmental factors make each person unique – which is why modifications such as changes in diet, exercise, medications and physical therapy can work well for one pain sufferer and not work at all for another, points out Dr. Rauck.

Epigenetics plus the vast number of genes we each have creates endless combinations of genes being turned on and off. If scientists could map every single cause and effect of the different combinations, and if we could reverse the gene’s state to keep the good while eliminating the bad… this would take pain genomics to the next level.

For now, we know that genetics plus lifestyle factors work together to impact pain sensitivity and predict pain conditions. More data – and time – is needed to develop meaningful patterns. Take heart in the fact that many, many physicians and scientists are working hard in this area. The future of using genetics to improve pain is certainly bright.