Congenital insensitivity to pain with partial anhidrosis

Congenital Insensitivity to Pain with Partial Anhidrosis (CIPA), also known as Hereditary Sensory and Autonomic Neuropathy Type IV (HSAN IV), is a rare genetic disorder characterized by the inability to feel pain and temperature, and decreased or absent sweating (anhidrosis). This condition is part of a group of disorders known as hereditary sensory and autonomic neuropathies (HSAN), which affect the nervous system.

Symptoms and Characteristics

Individuals with CIPA do not perceive pain in the way most people do, leading to an increased risk of injuries, infections, and other health issues unnoticed due to the lack of pain feedback. The anhidrosis aspect of the disorder can cause problems with regulating body temperature, leading to episodes of hyperthermia, especially in hot environments or during physical activity.

Other symptoms may include:

• Self-mutilating behaviors, such as biting the tongue, lips, or fingers, due to the lack of pain sensation.
• Repeated fractures or injuries without pain awareness.
• Intellectual disability or developmental delays in some cases.
• Inability to sweat normally, leading to recurrent fevers without an apparent cause.

Causes

CIPA is caused by mutations in the NTRK1 gene, which encodes for the receptor tyrosine kinase for nerve growth factor (NGF). This receptor is crucial for the development and survival of certain types of sensory neurons and sympathetic neurons. Mutations in the NTRK1 gene disrupt the normal signaling pathways, leading to the symptoms observed in CIPA.

Diagnosis

Diagnosis of CIPA is based on clinical findings, family history, and genetic testing. The presence of typical symptoms such as insensitivity to pain, anhidrosis, and self-mutilation behaviors can prompt further investigation. Genetic testing can confirm the diagnosis by identifying mutations in the NTRK1 gene.

Treatment and Management

There is no cure for CIPA, and treatment focuses on managing symptoms and preventing injuries. Strategies may include:

• Regular monitoring and care of the skin and bones to prevent and treat injuries and infections.
• Use of protective gear to prevent injuries.
• Education and behavioral interventions to minimize self-mutilation behaviors.
• Management of body temperature, especially in hot environments, to prevent hyperthermia.

Prognosis

The prognosis for individuals with CIPA varies. With careful management, individuals can lead relatively normal lives. However, the risk of life-threatening injuries or complications remains high due to the lack of pain sensation and inability to sweat normally.

See Also

• Hereditary Sensory and Autonomic Neuropathies
• NTRK1
• Pain
• Anhidrosis