A genetic link between a rare heart rhythm disease and an increased risk for seizures proves a clear association between the heart and the brain of such patients.
Long QT syndrome (LQTS) is a rare heart rhythm condition that can potentially cause fast, chaotic heartbeats. These rapid heartbeats might trigger a sudden fainting spell or seizure.
‘patients carrying LQTS genetic mutations were three times more likely to have experienced seizures in their past, compared to their family members who did not carry those mutations.’
People with LQTS who experience seizures are at greater risk of sudden cardiac death.
"Seizure status is the strongest predictor of cardiac arrhythmias - the abnormal heart rhythms characteristic of LQTS," said lead author David Auerbach from University of Rochester in New York, US.
In fact, about 20 percent of the LQTS patients in the study who had a history of seizures had survived at least one lethal cardiac arrhythmia.
For the study, the team analysed of more than 18,000 people affected with LQTS as well as their affected and unaffected family members, who provide a nearly ideal group of controls.
"In essence, they have the same genetic makeup, except theoretically, the LQTS-causing mutation," Auerbach added.
Analysing patients' genetic information, the team found that among the three different types of LQTS (LQTS1-3) patients with LQTS1 and LQTS2 had much higher prevalence of seizures than LQTS3 or no mutation - with LQTS2 at the greatest risk.
Further investigation of the LQTS-causing mutation showed that the specific location of the mutation greatly affected the risk of cardiac arrhythmias and seizures.
In one location on the gene, the mutation protected against these symptoms, but in another location on the same gene, the mutation increased the risk of those symptoms.
Understanding what each of these mutations does may shed new light on a basic mechanism of seizures and may provide viable therapeutic targets to treat LQTS, the researchers cocnluded.