Evolutionarily, the sensation of pain exists to alert us that something is wrong with our bodies. From a burning sensation when we touch a hot pan to the sourness that churns in our tummies when we drink spoiled milk, pain makes us aware that we need to pay attention and fix a problem.
Often times, though, doctors encounter patients who experience pain differently. Some people quite simply don’t experience pain at all. One man took a spill on an innertube, and at a regular checkup eight months later, he learned to his great surprise that he had broken 3 vertebrae. Former Indiana Colts head coach Tony Dungy raised a son with this same disorder. Put most simply, his brain didn’t “understand” the signals that injuries usually produce, and thus didn’t alert Jordan that something was amiss. Parents and therapists had to help Jordan adapt other ways to make sure he was healthy.
Others, on the other hand, are in constant chronic pain stemming from no injury or sickness whatsoever. One woman interviewed by Wired Magazine reported that, as a child, her joints hurt so badly that she could find solace only by wading in gutters and letting the cool sludge run over her burning hands. Today, she regularly takes morphine to dull the constant sensation of chronic prickly burning she lives with, in addition to sleeping on chilled pillows and wearing only loosely clothing. Many who suffer from opioid addictions develop a dependence because of chronic, intolerable pain.
As it turns out, both of these disorders stem from a genetic root, and as such, doctors can integrate pharmacogenomics into the way they treat patients with wildly abnormal pain tolerances, either low or high. Dr. Stephen Waxman has spent his career in neuroscience studying the pathology of pain. Put most simply, a person senses pain when neurons at the location of the injury tell the neuron next to it that something bad happened, and the neurons play telephone until the signal reaches the brain. Neurons “talk” to each other by means of chemical channels, and pain in particular uses the sodium ion channel called Nav1.7 to relay this message. Dr. Waxman hypothesized that individuals with faulty Nav1.7 channels may have wildly different experiences with pain, feeling it either never or always.
Scientists started investigating gene SCN9A, which codes for these sodium ion channels and determines their level of functionality. Between a Chinese research lab and Dr. Waxman’s work, it became clear that a miscoded version of the SCN9A gene could restrict or deluge the flow of sodium across the channel and determine how the person experienced pain. Shortly thereafter, researchers postulated as to whether they could create a drug that “plugs up” overactive Nav1.7 channels in those with faulty SCN9A genes. They came up with a drug called TV-45070 which is now in phase 2 of clinical testing.
The pharmacogenetic implications of being able to reduce genetically-influenced pain are huge. Not only could those suffering from Burning Man Syndrome finally find peace, but perhaps those who find themselves dependent on opioids for relief now have a safer way to reduce their pain.