NTRK1
Congenital insensitivity to pain with anhidrosis (CIPA) is caused by a mutation in the neurotrophic tyrosine kinase receptor type 1 gene (NTRK1) [1]. The NTRK1 gene mutation is detected in CIPA patients all over the world [2]. The NTRK1 gene makes a protein that is essential for the development and survival of sensory neurons; if this gene is defective, it can set off a chain of events that can lead to sensory neuron death. People with CIPA lose the ability to feel pain due to the loss of these sensory neurons. Some people with CIPA also lose the nerves leading to their sweat glands, which causes anhidrosis [1].
References
[1] "NTRK1." - Neurotrophic Tyrosine Kinase, Receptor, Type 1. U.S. National Library of Medicine, 28 Jan. 2013. Web. 04 Feb. 2013. <http://ghr.nlm.nih.gov/gene/NTRK1>.
[2] Indo, Y. (2001), Molecular basis of congenital insensitivity to pain with anhidrosis (CIPA): Mutations and polymorphisms in TRKA (NTRK1) gene encoding the receptor tyrosine kinase for nerve growth factor. Hum. Mutat., 18: 462–471. doi: 10.1002/humu.1224
[2] Indo, Y. (2001), Molecular basis of congenital insensitivity to pain with anhidrosis (CIPA): Mutations and polymorphisms in TRKA (NTRK1) gene encoding the receptor tyrosine kinase for nerve growth factor. Hum. Mutat., 18: 462–471. doi: 10.1002/humu.1224