Those of you from the state of Tamilnadu,India must be knowing what THAIPOOSAM is. What fascinates me about the event is the fervour with which the devotees perform acts like tongue and body piercing with vels, walking barefoot over hot coal etc.. It is surprising to note they do not feel the pain at all.
Do they all have a gene mutation in SCN9A ? I do not know.
Nerve fibers have different proteins embedded in their endings, each of which is sensitive to a different kind of injury. These sensor proteins act by letting a few sodium ions flow into the nerve, though not enough to set off a pain signal. The proteins made by the SCN9A gene amplify the initial activity by letting a much larger number of sodium ions flow in, initiating an electrical signal that is interpreted as painful when it reaches the brain.
There are many who does such offerings.All of them are not professionals.I doubt all of them carry mutations in the gene for pain.