The Genetics Behind How Much Pain You Feel

A new scientific study seems to suggest that the difference between people who laugh when they get hurt and those who are in excruciating pain from the same type of injury is purely genetic. The research group behind the new investigation says that sensitivity to pain is dictated by subtle variations in a number of genes, and that DNA is basically responsible for this. The new finding builds on previous investigations, all conducted over the past 5 years, which showed that three serious pain disorders are caused by mutations in a specific gene. The group just took it from there, ScienceNow reports.

The main culprit was identified as the SCN9A gene, which plays an important part in controlling sodium channels inside nerve cells. Neurons in the body form the pathways through which the electrical signals coming from the site of an injury are transmitted to the brain. The more clearly the signal passes, the more pain you are likely to experience. What this particular gene does is that it encodes instructions on how the sodium channels in these nervous pathways should function.

According to the previous studies, it would appear that malfunctions in the gene cause the sodium channels to open too easily or not close at all, thus facilitating the unadulterated transmission of pain-related electrical signals to the brain. This is especially true in two of the three conditions that were analyzed. Conversely, in the third disorder that other science teams analyzed, the gene produces a protein that could not function, and therefore that person could not experience pain at all. All of these disorders are very severe, but fortunately very rare.

“We wondered if more common, apparently harmless [changes] in the gene might give rise to an altered degree of pain threshold,” explains Cambridge University medical geneticist Geoffrey Woods, the leader of the new research effort, and the leader of the team that made the groundbreaking find about the third pain disorder. The new experiments were conducted on about 578 people suffering from osteoarthritis, a condition that makes people's bones hurt when they grow older. The investigators looked at all 27 subtle genetic variations that could take place in the individuals. These mutations are called single-nucleotide polymorphisms (SNP). Full details of the work appear in the latest online issue of the respected journal Proceedings of the National Academy of Sciences (PNAS).