One of the best methods to study the effect of genes on our lives is to use identical twins. Although these twins have identical sets of genes, they can be different in many ways: emotions, temperament, interests, and even pain sensitivity. Regulatory markers on our genes can make them more or less likely to be used in a cell and propagated throughout or bodies. Researchers think these chemical markers work like an “on/off switch” for genes and are strongly influenced by the environment. So, while the genomes of twins are identical, the expression of slightly modified genes can be quite different thus explaining inconsistencies between twins.
Recently, investigators at King’s College in London looked at how such modifications of our genes can affect pain sensitivity. They decided to test heat-pain thresholds on 50 pairs of twins that showed “substantial” differences in pain sensitivity. This begs the question: If these twins have identical genes, why do they say “Ow!” at different stimulus intensities? After taking blood samples, the researchers found that the twins had different chemical markers, or methylation, on nine different genes. Those twins that had more methylations on the TRPA1 gene showed increased pain sensitivity while those twins with less methylation tended to be more pain-resistant.
Hence, this could mean pain sensitivity isn’t completely inherited or permanent. Moreover, it could mean that chronic pain itself could be reversible. Companies could start looking at the TRPA1 gene and change its expression with targeted drug therapy. Still, more research must be done before translating this into clinical practice but such therapy would open up a completely new way of changing pain sensitivity.
At the UF Pain and Fatigue Research Center, we are exploring the changing pain sensitivity of chronic pain patients as well as pain-less individuals. We use qualitative sensory testing (QST) to track how pain sensitivity changes over time. For more information, please contact us at 352-265-8901 or by email at painresearch@medicine.ufl.edu
Ricky Madhavan, BA
Senior Laboratory Technician
UF Center for Musculoskeletal Pain Research