What can you tell me about congenital insensitivity to pain with anhidrosis?

Very rare. A genetic mutation that leads to increase risk of both heat injury due to inability to sweat and cool oneself and the lack of protective reflexes due to pain. I reviewed these article that may help you with more of your questions http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3371914/ http://ghr.nlm.nih.gov/condition/congenital-insensitivity-to-pain.