What are the genetic changes related to paroxysmal extreme pain disorder ?
Mutations in the SCN9A gene cause paroxysmal extreme pain disorder. The SCN9A gene provides instructions for making one part (the alpha subunit) of a sodium channel called NaV1.7. Sodium channels transport positively charged sodium atoms (sodium ions) into cells and play a key role in a cell's ability to generate and transmit electrical signals. NaV1.7 sodium channels are found in nerve cells called nociceptors that transmit pain signals to the spinal cord and brain.  The SCN9A gene mutations that cause paroxysmal extreme pain disorder result in NaV1.7 sodium channels that do not close completely when it is turned off, allowing sodium ions to flow abnormally into nociceptors. This increase in sodium ions enhances transmission of pain signals, leading to the pain attacks experienced by people with paroxysmal extreme pain disorder. It is unknown why the pain attacks associated with this condition change location over time or what causes the other features of this condition such as seizures and changes in breathing.