Myshkin mice can develop severe seizures
Scientists have prevented epilepsy caused by a faulty gene from being passed down the generations in mice.
The key gene, Atp1a3, regulates levels of chemicals such as sodium and potassium in brain cells.
It has long been suspected that an imbalance of these chemicals may cause some cases of epilepsy.
The University of Leeds study, which appears in Proceedings of the National Academy of Sciences, raises hopes of new treatments for the condition.
Lead researcher Dr Steve Clapcote said: "An imbalance of sodium and potassium levels has long been suspected to lead to epileptic seizures, but our study is the first to show beyond any doubt that a defect in this gene is responsible."
Much work is needed to determine whether the same mechanism is in play in humans.
But the human ATP1a3 gene is more than 99% the same as the mouse version.
Epilepsy is a common neurological condition that affects almost one in every 200 people.
However, the causes are unknown in the majority of cases.
Current drug treatments are ineffective in around one third of epilepsy patients.
The Leeds team worked on Myshkin mice, which have a tendency to develop seizures.
Scan showing epilepsy activity in a mouse brain
They showed that those animals who did develop seizures carried a specific defective version of Atp1a3.
These mice responded when treated with the common anti-epileptic medication valproic acid - proving that they did indeed have a form of epilepsy.
To try to counter this, the researchers bred the epileptic mice with animals that carried an extra copy of the normal Atp1a3 gene.
The addition of the normal gene counteracted the faulty gene in the resulting offspring - which were completely free from epilepsy.
Dr Clapcote said: "Our study has identified a new way in which epilepsy can be caused and prevented in mice, and therefore it may provide clues to potential causes, therapies and preventive measures in human epilepsy."
"Our results are very promising, but there's a long way to go before this research could yield new antiepileptic therapies."
Dr Clapcote said his team had started to screen DNA samples from epilepsy patients to investigate whether Atp13a gene defects were involved in the human condition.
Delphine van der Pauw, of the charity Epilepsy Research UK, said: "These results are promising.
"If the findings can be repeated in human studies, new avenues for the prevention and treatment of inherited epilepsy will be opened."
Simon Wigglesworth, of Epilepsy Action, stressed the research was at an early stage - but agreed that it was encouraging.
He said: "At the moment there is no treatment to cure epilepsy, other than surgery, which is only effective for small numbers."