By comparing the gene sequence of a girl who cannot feel pain to that of her parents who can, researchers believe they could develop more effective pain medication. A research team from Jena University Hospital in Germany discovered a gene mutation that could block the transmission of pain receptors.
"With this new gene, it's the opposite: when it's overactive, they feel no pain. So maybe it's some kind of gatekeeper that stops neurons from firing too often, but cancels pain signals completely when it's overactive," Geoffrey Woods from the University of Cambridge told New Scientist. "If you could get a drug that made SCN11A overactive, it should be a fantastic analgesic."
Congenital analgesia is a rare condition that leaves a person unable to feel pain. Although this may sound like a dream come true, people with this disorder often don’t feel themselves breaking a bone or getting burnt. Many people don’t live past the age of 30 due to the physical toll that the condition takes on the human body.
“Interestingly, those with congenital analgesia can still feel sensations such as normal body-to-body contact, which means that the brain can receive some information filtered through the nervous system: Perception of passive movement, joint position, and vibration is normal, as are tactile thresholds and light touch perception,” explained Mark Borigini, M.D.
After comparing the young girl's gene sequence to her parents' gene sequence, researchers were able to identify the gene SCN11A. They discovered that the mutated version of this gene can prevent the buildup of neurons that transmit electrical impulses of pain, New Scientist reported.
By inserting this mutated gene into mice and testing their ability to feel pain, the team found that 11 percent of these mice developed injuries similar to those found in people with congenital analgesia. A control group without a mutated SCN11A gene showed no signs of injury. A second test dubbed the “tail flick” test, where mice were placed under a heat lamp and timed to see how long they could stay under without flicking their tail, showed that mice with the altered gene took two-and-a-half times longer to react.
"What became clear from our experiments is that although there are similarities between mice and men with the mutation, the degree of pain insensitivity is more prominent in humans," said lead researcher Ingo Kurth.
Source: Timmerman V, Schaible H, Weis, J, Heinemann S, Hübner C, Kurth I. A de novo gain-of-function mutation in SCN11A causes loss of pain perception. Nature Genetics. 2013.