Congenital Insensitivity To pain with Anhidrosis is caused by a mutation in gene NTKR 1. NTKR 1 or neurotrophic tyrosine kinase, receptor, type 1 holds the "instructions" to producing a receptor protein which with attach to NGFB protein. NTKR 1 receptor is found on the end of neurons that transmit pain and heat. When NGFB binds with the NTKR 1 receptor signals are sent inside the cell that helps it survive. The mutation of your NTKR 1 gene leads the NGFB protein not being able to send signals. Without these signals the neurons will process of self-destruction called apoptosis, causing the inability to feel pain. In addition this leads to losing the nerve endings in you sweat gland causing anhidrosis, meaning you can't sweat.

 

The mutated gene causing CIPA is recessive. This means unless you get the mutated gene from both parents you will not have CIPA. If you have one mutated NTKR 1 gene you will likely not show any symptoms at all. Below is a punnet square of the one other combination that could cause CIPA besides two people with CIPA.