A mutation in a gene called RyR2 may increase the risk of sudden unexpected death in epilepsy (SUDEP), according to a new study published in the leading scientific journal Proceedings of the National Academy of Sciences (PNAS).
The authors believe that this is an important step towards being able to predict the risk of SUDEP in a person with epilepsy and take necessary measures to avoid it.
In a press release, Senior Author Dr Jeffrey L. Noebels, from the Baylor College of Medicine in Houston, said: “We have been looking for genes that cause epilepsy to see if any of them might give us a clue as to who might be at risk (of SUDEP). Specifically, we have been looking at genes that might explain what appears to be a collapse of the cardiac and respiratory system after a seizure.”
Dr Noebels and his team have identified mutations in several genes expressed* in the brain and heart that cause an abnormal heartbeat and epilepsy in rodents. Most recently, they have shown that a mutation in the RyR2 gene causes both heart problems and seizures in mice.
The Ryr2 (or ryanodine receptor 2) gene encodes a protein that plays a role in regulating the level of calcium inside cells. Calcium levels inside neurons influence their communication by mediating the amount of neurotransmitter that is released from them. The mutation in the Ryr2 gene causes the amount of calcium inside cells to be higher than normal, resulting in the amount of neurotransmitter released from neurons to be too high. This triggers seizures.
The authors found that it was much easier to experimentally trigger blackouts in the brainstem of mice carrying a mutation in the Ryr2 gene than in mice that did not have the mutation. Mice that had these blackouts in the brain stem, where breathing and heart function are regulated, were prone to sudden death.
Approximately 6% of people with epilepsy have a higher than usual incidence of SUDEP, and SUDEP is the most common cause of premature death in people with epilepsy.
The term ‘gene expression’ refers to the process by which information from a gene is used to create a functioning gene product, very often a protein.
Author: Dr Özge Özkaya
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