CIPA disease is caused by a mutation in the NTRK1 gene. This gene provides instructions for making a protein that is involved in sending signals from nerve cells to the brain. The NTRK1 protein is found in a type of cell called a sensory neuron. Sensory neurons are responsible for transmitting information about touch, temperature, pain, and other sensations to the brain.
The NTRK1 gene mutation that causes CIPA disease results in the production of an abnormal NTRK1 protein. This protein is not able to send signals from nerve cells to the brain. As a result, affected individuals do not develop the ability to feel pain. In addition, they are unable to sweat, which can lead to an inability to regulate body temperature.