CIPA stands for congenital insensitivity to pain with anhidrosis, a rare genetic condition in which a person is born unable to feel physical pain and unable to sweat. It affects roughly 1 in 125 million newborns worldwide, making it one of the rarest disorders known to medicine. People with CIPA can still feel pressure and touch, but they have no sensation of sharp, burning, or aching pain, and their bodies cannot regulate temperature through sweating.
What Causes CIPA
CIPA is caused by mutations in a gene called NTRK1. This gene provides the blueprint for a receptor protein on nerve cells that binds to nerve growth factor, a chemical signal the body uses to build and maintain certain types of neurons during development. When the NTRK1 gene is mutated, the receptor doesn’t work properly, and those critical growth signals never get through.
More than 100 distinct mutations in the NTRK1 gene have been identified in CIPA patients. Most of these mutations affect the part of the receptor responsible for relaying signals inside the cell. Without that relay working, two things happen during embryonic development and early childhood: the small nerve fibers responsible for detecting pain and temperature undergo programmed cell death, and the nerve cells that control sweat glands either die off or never develop correctly. The result is a body that can’t sense danger through pain and can’t cool itself through perspiration.
CIPA follows an autosomal recessive inheritance pattern, meaning a child must inherit a defective copy of the gene from both parents. It is more common in populations with higher rates of marriage between close relatives. The condition is particularly concentrated among Japanese populations, Israeli Bedouin communities, and certain Chinese populations. A 10-year study reviewed 63 CIPA patients, all from consanguineous Bedouin families, illustrating how tightly the condition clusters in specific communities.
How CIPA Is Classified
CIPA is formally classified as hereditary sensory and autonomic neuropathy type IV (HSAN IV). It belongs to a family of related conditions that affect sensory nerves in different ways. Type V, for example, also involves an inability to feel pain but does not include the sweating problems or intellectual disability that define type IV. The distinction matters because the inability to sweat is what makes CIPA uniquely dangerous in its own category.
Symptoms and How They Appear
CIPA typically becomes apparent in infancy, often before a diagnosis is made. The earliest sign is usually unexplained fevers. Because the baby cannot sweat, even mild exertion or a warm room can cause body temperature to spike. Parents may also notice that the child doesn’t cry or pull away from things that should hurt: a hot stove, a sharp edge, a vaccination needle.
As children grow, the consequences of painlessness become more visible. Young children with CIPA commonly bite their own tongues, lips, and fingers, not out of distress but simply because they receive no feedback telling them to stop. Burns from hot food or surfaces go unnoticed. Oral injuries, including self-extraction of baby teeth, are frequent. These injuries have sometimes been mistaken for signs of child abuse before the underlying condition was recognized.
Most individuals with CIPA also experience some degree of intellectual disability, typically described as mild. In case studies, the majority of affected children attended special education programs. Importantly, people with CIPA retain their sense of pressure and touch. They can feel someone squeezing their hand or pressing on their skin. What’s absent is the warning system: the sharp, urgent signals that tell the brain something is being damaged.
The Danger of Not Sweating
The “anhidrosis” half of CIPA is arguably more immediately life-threatening than the pain insensitivity. Sweating is the body’s primary cooling mechanism. Without it, body temperature can climb rapidly during physical activity, warm weather, or even a mild illness. Recurrent episodes of dangerously high body temperature are one of the hallmark features of the condition, and controlling environmental temperatures is considered essential to managing it.
Regular temperature monitoring is a core part of care for anyone with CIPA. Families learn to watch for early signs of overheating and to keep living spaces cool. Timely detection of rising body temperature can prevent heat stroke and the organ damage that follows.
Orthopedic and Skin Complications
Without pain to signal injury, bones and joints take a beating over time. Stress fractures in the legs are common because the person never feels the early ache that would normally cause them to limp or rest. Repeated unnoticed fractures can lead to poor healing, chronic bone infections, and a condition called Charcot joints, where a joint gradually deteriorates and becomes unstable because microtrauma accumulates without the person ever guarding the area. Joint instability, abnormal bone growth, and progressive curvature of the spine (scoliosis) are all documented complications. Surgical correction of scoliosis in CIPA patients carries a high risk of post-operative infection, often requiring additional operations.
Skin problems are also persistent. Because the sweat glands don’t function normally, the skin tends to be chronically dry, with thickened, cracked skin on the palms and soles. Daily moisturizing is a basic but important part of the care routine. Cracked skin creates entry points for bacteria, and infections that would normally be caught early (because they hurt) can progress significantly before anyone notices.
How CIPA Is Diagnosed
Diagnosis usually begins when a pattern of unexplained fevers, unusual injuries, and lack of pain response raises suspicion. Doctors assess whether the child sweats normally and examine for signs of oral self-injury, burns, or dry skin. A sweat test can confirm whether the sweat glands are functioning. Genetic testing for mutations in the NTRK1 gene provides the definitive diagnosis. Because CIPA is so rare, there can be significant delays between the first symptoms and a confirmed diagnosis, sometimes years.
Living With CIPA
There is no cure for CIPA, and no treatment can restore the missing nerve fibers or sweat glands. Management revolves entirely around prevention: preventing injuries, preventing overheating, and catching complications early before they become severe.
In practical terms, this means daily skin checks for wounds or infections the person can’t feel, careful monitoring of body temperature, and environmental controls to avoid heat exposure. Dental exams are recommended at least every six months because of the high risk of oral injuries and tooth damage. Young children may need protective measures to prevent self-biting, such as dental guards or, in some cases, early extraction of teeth that pose a risk.
Families also learn to do regular visual inspections of the feet, legs, and hands for signs of fractures or joint swelling. Because the person won’t report pain, a limp or swelling might be the only clue that a bone has broken. Orthopedic follow-up becomes a routine part of life, especially during the growth years when bones are under the most mechanical stress.
People with CIPA can and do survive into adulthood, though the condition demands constant vigilance. The greatest risks, particularly in childhood, come from hyperthermia and undetected infections. With attentive care and a well-adapted environment, many of those risks can be managed, but the margin for error is narrow in a body that never sounds its own alarms.