Congenital insensitivity to pain is a serious condition affecting a handful of people in the U.S. While at first, these few individuals sound like the lucky ones (no stubbed toes for them!), they are actually at constant risk of severe injury and even death. Imagine not knowing that you’ve been walking around with a broken arm since that time you slipped on the stairs. Or not realizing that you’ve been running a high fever due to an infection. Pain is much more our friend than we appreciate.
We now know that at least one cause of congenital insensitivity to pain is a mutation in the gene SCN9A, which encodes a sodium ion channel. Ion channels are gates in nerve cell membranes that control the flow of ions, and thus the electrochemical gradient, across the neural membrane. This gradient is propagated along the length of the nerve cell in the form of an electrical impulse. Nerves receive and send signals via these electrical impulses.
Messing with the ion channels can make nerve cells either over or under-react to stimuli. Researchers have found both affects from mutations to SCN9A. Patients with no functional SCN9A have congenital insensitivity to pain, whereas those with an overactive gene feel intense, unwarranted pain.
Although only a very few people ‘suffer’ from the lack of pain, a great many experience too much pain, such as those suffering from ‘phantom limb pain’ about which I recently wrote. Researchers hope this new data will yield therapies to block pain.