36-year-old Steve Pete has never felt physical pain in his life. While that may sound appealing, it comes with some serious downsides, such as literally chewing off his own tongue as an infant. He was later diagnosed with congenital insensitivity to pain (CIP), which a genetic test revealed rose from a mutation in the SCN9A gene, which is responsible for creating a sodium channel called NaV1.7. The condition is rarer than rare– there are only about 20 recorded cases.
Dr. Stephen Waxman, a neurology professor at Yale, and director of the Neurorehabilitation Research Center at VA Connecticut, compares this gene to a volume knob controlling pain– Pete’s metaphorical knob would be turned down completely.
This pain volume knob can also be turned up, far louder than it’s meant to go. This is the issue that Reid Millius faced, who has been struggling with pain her whole life. There were no visible signs on her body, besides patches of redness, so even though the pain attacks were at times, severe enough to land her in the hospitals, doctors dismissed it. After they insisted it was psychosomatic, she eventually resigned to the idea.
Then Millius’s niece started to feel the extreme pain too. That’s when Millius started doing serious investigation, and discovered erythromelalgia, also known as man on fire syndrome. Like Pete’s CIP, erythromelalgia is also caused by a mutation in the SCN9A gene, impacting the NaV1.7 sodium channel. The conditions are liked flipped images of each other– in Pete, the mutation meant the gene lost its function, and in Millius, the mutation meant the gene gained extra function.
Erythromelalgia is a rare and excruciatingly painful condition, primarily affecting extremities. It causes burning pain, high skin temperature, and red appearance. For some people, this is episodic, and for others, it’s all the time. There is no cure, only symptom management. To learn more about erythromelalgia, click here.
Millius and Pete are two very sought-after patients– researchers like Waxman have been searching for examples of these conditions in order to gain better understanding of the mysterious and incredibly diseases. The implications of their disorders spread beyond their own lives– by understanding their pain (or lack thereof) researchers can better understand pain as it pertains to other diseases. Waxman tells CNN that while he’s seen many instances of neuropathic pain, inherited neuropathic pain is a whole different story. He began searching for pain patterns that ran in families, to learn about the genetic nature of pain.
Around 6 pharmaceutical companies have already started running experiments, in order to learn how to emulate Pete’s disease to help patients like Millius, as well as patients who battle other types of chronic pain.
One of the big reasons this call to action is so urgent, is because our current pain treatments come with weighty problems. While opioids are commonly prescribed to manage chronic pain, they’re addictive and dangerous. An opioid epidemic is sweeping the country, and causing devastation and death. The treatment these researchers are working on wouldn’t be addictive, or have the heavy side effects of opioid.
The treatment wouldn’t act on the brain itself, but instead a path that signals pain to peripheral nerves. Researchers are testing out all different types of molecules to see what modifies NaV1.7. They’re currently looking at a treatment derived from one unlikely source: venom from the Chilean tarantula.
There are certainly challenges ahead of these research teams. Pain is hard to measure empirically– it doesn’t have the clear parameters like heart rate or blood pressure. It’s measured subjectively, and that works against the team.
Still, the scientists are excited. Who wouldn’t want to see a world where patients can effectively manage chronic pain, without the side effects of opioids?
Read the original article on CNN here.
