Congenital insensitivity to pain (Congenital insensitivity to pain) - Gen SCN9A.
Congenital insensitivity to pain is a disorder that inhibits the ability to perceive the physical pain. From birth, affected individuals do not feel pain anywhere in your body after an injury. Affected people may feel the difference between hot and cold, but can not detect, for example, that a hot drink is burning his tongue. This lack of awareness of pain often leads to an accumulation of wounds, bruises, broken bones and other health problems that may go unnoticed. Often, these repeated injuries lead to reduced life expectancy in affected individuals. In addition, many people with congenital insensitivity to pain also have anosmia.
The congenital insensitivity to pain is considered a form of peripheral neuropathy, affecting the peripheral nervous system, connecting the brain and spinal cord to the muscles and the cells that detect sensation like touch, smell , and pain.
This process is due to mutations in the SCN9A gene, located on the long arm of chromosome 2 (2q24). This gene encodes a portion (the alpha subunit) Nav1.7 sodium channel. These channels convey sodium ions into cells and play a key role in the ability of a cell to generate and transmit electrical signals. Nav1.7 sodium channels are found in nociceptors that transmit pain signals to the spinal cord and brain. The Nav1.7 channel is also found in olfactory sensory neurons.
They have identified at least 13 SCN9A gene mutations that result in congenital insensitivity to pain. These mutations create a premature stop signal encoding the alpha subunit of the sodium channel Nav1.7. Consequently, a non - functional subunit can not be incorporated in the channel coding, leading to a loss of functional sodium channel Nav1.7. The loss of these channels affects the transmission of pain signals in the lesion site in the brain, leading to pain insensitivity. The loss of this channel in olfactory sensory neurons probably impairs the transmission of signals related to smell in the brain, leading to anosmia.
This disease is inherited in an autosomal recessive pattern, that is, both copies of the gene in every cell must have mutations for alteration is expressed. The parents of an individual with an autosomal recessive disease have a copy of the mutated gene, but usually show no signs and symptoms of the disease.
Tests in IVAMI: in IVAMI perform detection of mutations associated with congenital insensitivity to pain by the complete PCR amplification of the exons of the SCN9A gene, and subsequent sequencing.
Samples recommended: EDTA blood collected for separation of blood leukocytes, or impregnated sample card with dried blood (IVAMI may mail the card to deposit the blood sample).