Tiny variations in a key gene on Chromosome 15 may help explain a common form of epilepsy, according to a paper published online on Sunday by the journal Nature Genetics.
As many as a third of all epileptic fits are called "idiopathic generalised epilepsy," or IGE, meaning that the genetic causes for them are unknown but likely to be highly complex.
Previous research has narrowed investigations into IGEs to a region on Chromosome 15.
Taking this further, a large consortium of scientists sifted through two large genetic databases of people who either had a history of IGE or were otherwise healthy.
In 12 of the 1,233 people with IGE, they spotted several microdeletions in a gene called CHRNA7, which regulates signalling between brain cells.
The telltale variations were not seen in any of the 3,699 healthy counterparts.
The flaws are the biggest risk factor yet seen for IGE, although they still account for just one percent of cases of these fits.
Epileptic seizures are triggered by abnormal, synchronised firing of neuron groups, which results in disruption to the central nervous system, causing spasms and convulsions, and in the worst cases, stopping breathing.
Approximately two to four percent of people will have a seizure at some point in their lives, while for epileptics, the experience can be repeated many times.
The vast majority of seizures stop by themselves. In some cases, though, the fit develops into a highly dangerous condition called status epilepticus that has a mortality rate of up to 20 percent.