Congenital insensitivity to pain with anhidrosis
|Congenital insensitivity to pain with anhidrosis|
|Classification and external resources|
Congenital insensitivity to pain with anhidrosis (CIPA), also called hereditary sensory and autonomic neuropathy type IV, is an extremely rare inherited disorder of the nervous system which prevents the sensation of pain, heat, cold, or any real nerve-related sensations (including feeling the need to urinate); however, patients can still feel pressure. CIPA is the fourth type of hereditary sensory and autonomic neuropathy (HSAN), known as HSAN IV. (It is also referred to as HSAN Type IV). A person with CIPA cannot feel pain or differentiate even extreme temperatures. "Anhidrosis" means the body does not sweat, and "congenital" indicates that the condition is present from birth.
People with this disorder are very likely to injure themselves in ways that would normally be prevented by feeling pain. For example, a patient could burn themselves severely and not even notice. The main features of the disorder are lack of pain sensation, painless injuries of the arms, legs and oral structures, hyperthermia during hot weather because of inability to sweat, syndromic intellectual disability as a result of hyperthermia, infection and scarring of the tongue, lips and gums, chronic infections of bones and joints, bone fractures, multiple scars, osteomyelitis and joint deformities, which may lead to amputation. Other common problems are eye related, such as infection due to the sufferers rubbing them too hard, too frequently or scratching them during sleep. In addition, patients typically lack unmyelinated and small myelinated nerve fibers in the dorsal root ganglion. Both are responsible for transmitting pain signals. In addition, patients' sweat glands are normal in both structure and function, though they lack innervations by small diameter neurons.
Congenital insensitivity to pain with anhidrosis may be misdiagnosed for leprosy, based on similar symptoms of severe injuries to the hands and feet.
CIPA is caused by a genetic mutation which prevents the formation of nerve cells which are responsible for transmitting signals of pain, heat, and cold to the brain. The disorder is autosomal recessive. It does not appear to have any particular ethnic distribution, though it is more prevalent in cultures in which intermarriage is an accepted practice. Overheating kills more than half of all children with CIPA before age 3.
The genetic mutation is in the gene encoding the neurotrophic tyrosine kinase receptor (SCN9A gene). NTRK1 is a receptor for nerve growth factor (NGF). This protein induces outgrowth of axons and dendrites and promotes the survival of embryonic sensory and sympathetic neurons. The mutation in NTRK1 does not allow NGF to bind properly, causing defects in the development and function of nociceptive reception.
In the media
The manga and anime series Loveless features a group of four characters, the Zero, with this condition. Notably they were genetically engineered to possess it as their creator believed being unable to feel pain would make them better warriors.
In the third season of the TV series House in the episode "Insensitive" (14th episode), the patient (Hannah Morganthal, played by Mika Boorem) suffers from this condition. In the third season of the TV series Grey's Anatomy in the episode "Sometimes a Fantasy", Abigail Breslin's character, Megan Clover, is diagnosed with this condition.
CIPA is examined in an episode of Mystery Diagnosis entitled The Boy Who Never Cried, featuring a child suffering from the disorder. The child's condition first emerges after the tip of their tongue ulcerates and is accidentally bitten off by the repeated action of it moving against the child's growing incisor teeth.
- Abdel-Hafez, Hisham; Sarah Mohamed Awad (June 2007). "Congenital Insensitivity to Pain with Anhidrosis (CIPA)". Egyptian Dermatology Online Journal. 3 (1). Retrieved 7 December 2011.
- Mardy, Sek; Yuichi Miura; Fumio Endo; Ichiro Matsuda; Yasuhiro Indo (2001). "Congenital Insensitivity to pain with anhidrosis (CIPA): effect of TRKA (NTRK1) missense mutations on autophosphorylation of the receptor tyrosine kinase for nerve growth factor". Human Molecular Genetics. 10 (3): 179–188. doi:10.1093/hmg/10.3.179. Retrieved 7 December 2011.
- Shatzky S, Moses S, Levy J, et al. (June 2000). "Congenital insensitivity to pain with anhidrosis (CIPA) in Israeli-Bedouins: genetic heterogeneity, novel mutations in the TRKA/NGF receptor gene, clinical findings, and results of nerve conduction studies". Am. J. Med. Genet. 92 (5): 353–60. doi:10.1002/1096-8628(20000619)92:5<353::AID-AJMG12>3.0.CO;2-C. PMID 10861667.
- Indo, Yasuhiro. "Mutations in the TRKA/NGF Receptor Gene in Patients with Congenital Insensitivity to Pain with Anhidrosis" (PDF). Kumamoto University. Retrieved 7 December 2011.
- The Facts of Painless People The website of two adults on separate sides of the world who were born with CIPA.
- Help Roberto The website of young boy with CIPA. Features Roberto's specific case, information about CIPA, and links to videos on CNN and the Discovery Channel. (Site has ended, link from Archive.org)