Pain

“Show someone an image of a pair of scissors cutting a hand, and the observer’s brain will react as much as if their own hand were being pinched…chronic pain, on the other hand, is a phantom…the hidden pain of others is easy to dismiss.”

https://www.wired.com/2017/04/the-cure-for-pain

This is a really interesting article in WIRED magazine about genetic similarities between people who don’t feel pain, and people with a particular type of chronic pain. In both cases, there is a gene, SCN9A, that controls a particular sodium channel, Nav1.7.

Mutations in SCN9A makes the NAV1.7 channel more likely to open (allowing harmless stimuli to trigger pain) and also stay open longer (amplifying pain). A different SCN9A mutation leads to an inactive NAV1.7 channel, leading to insensitivity to pain.

So now, several companies are working on ways to selectively block NAV1.7.  This would be life changing for those with chronic pain, which is generally very difficult to manage.