Sodium channel gene linked to epilepsy syndrome

Epilepsy is a diverse disorder comprising several syndromes with one of the most common being mesial temporal lobe epilepsy with hippocampal sclerosis (MTLEHS). The cause of this disease is unknown but it is often associated with a history of fever-related convulsions in childhood and is typically resistant to drug treatment. It may be treated surgically, however, but only 50% of patients are free of seizures in the long-term.

Some rare epilepsies have been linked to a mutation in the SCN1A sodium channel gene. In a study led by Sanjay Sisodiya from the Institute of Neurology at University College London, and including Daniah Trabzuni from King Faisal Specialist Hospital and Research Centre in Riyadh, researchers conducted a genome-wide association study on 1,977 people with MTLEHS, including cases with and without a history of fever fits.

They found a significant relationship between MTLEHS accompanied with convulsions and the sodium channel gene cluster on chromosome 2q24.3 which encompasses SCN1A and other sodium channel genes. These findings suggest involvement of the SCN1A gene and therefore, possible genetic susceptibility to MTLEHS.

"This is an important finding as it gives new insight into how MTLEHS might develop after a febrile seizure. Further work is now needed to explore the underlying mechanisms," says Sisodiya. "It might be possible in the future that the risk of MTLEHS after febrile seizures could be more accurately predicted in individual cases, and it might even be possible to consider preventative or precautionary measures in such cases – but we are not there yet."

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