Congenital insensitivity to pain with anhidrosis (CIPA) is one of the rare conditions which deals with the inability to sense pain. Do you think that’s great? They won’t suffer. They could live in a world without pain? No! It’s worse. Pain is the feeling that tells us that something is wrong and needs to be fixed. It is not the case in CIPA. When the individual is in an extreme environment, he/she can feel the warmth or coolness but cannot sweat. As a result, more heat accumulates in the body resulting in a condition called anhidrosis. This heat effects in the long run by causing extremely high fevers and internal problems.
Signs and symptoms of CIPA
The signs appear early in childhood. Inability often leads to repeated severe injuries. Kids can bite their tongue, cut their hands, and have no idea about the pain and the bleeding it’s going to result in. Additionally, it takes a lot of time for the patients to heal the wounds. These self-inflicting injuries can also result in premature death. Repeated trauma can lead to chronic infections in which the surrounding tissues destroy.
People suffering from CIPA also have thick skin that makes them unable to feel pain. They also have patches on their scalp, where hair doesn’t grow. They have weak muscle tone when young but gradually improves over time. The MRI can help diagnose the condition as the physical and emotional pain lights the same regions of the brain.
Genetic inheritance
The condition is due to genetic inheritance. It is an autosomal recessive disorder in which both copies of the gene are mutated. The parents of the patient are usually the carriers i.e., have a single mutated allele. The single mutated allele will not affect the carriers. PRDM12 and SCN9 are the two essential genes playing a role in this condition. PRDM12 acts as a genetic switch. It modifies chromatin. Chromatin plays a significant role in the formation of nerve cells. The function of SCN9 is to transmit nerve impulses in pain-sensing neurons. Moreover, the SCN9 gene provides the genetic instructions to make ‘sodium channel’ protein. The channel involves in transmitting nerve impulses to the brain and spinal cord via pain neurons.
Gene mutational factors responsible for CIPA
Mutations in NTRK (Neurotrophic tropomyosin receptor kinase) gene also cause Congenital insensitivity to pain with anhidrosis (CIPA). NTRK gene is responsible for sensing heat, temperature, and transmitting pain. It is present on the surface of sensory cells and acts as a kinase. When the NGFβ (Nerve growth factor-Beta) binds to the NTRK gene, it transmits signals that tell the cell to divide and is also responsible for inducing the self-phosphorylation of NTRK protein. But, in case of a mutation, protein cannot bind, and hence no division occurs. Without proper signaling, the neurons undergo a self-destruction process called apoptosis. The loss of sensory neurons results in CIPA.
Treatment for insensitivity to pain
It’s a rare disorder. Despite the odds, scientists developed a drug called Naloxone. It is used in treating opioid overdoses and causes life-threatening depression of the nervous system. Opioids block the sensation of pain, and Naloxone inhibits this blockage.
One of the diagnosed cases of CIPA is Ashlyn Blocker, who lives with her parents in the US town of Patterson, Georgia. She is one of a small number of people in the world who have been diagnosed with CIPA.
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