Epilepsy sufferers have been given fresh hope that a cure may be found after scientists prevented the condition being passed on to mice offspring, in a breakthrough described as "very exciting" by epilepsy charities.
Scientists at Leeds University said they had proved that a faulty version of the gene which makes an enzyme called sodium-potassium pump is responsible for passing on the disorder.
The mice, which have the faulty gene, known as ATP(12A)3, were bred so that they also carried a normal version of the same gene. Researchers found that the two genes counter-acted each other, preventing the condition from being passed from generation to generation.
The study, published yesterday in the US journal Proceedings of the National Academy of Sciences (PNAS), could be good news for the estimated 450,000 British epileptics.
"Our study has identified a new way of in which epilepsy can be caused and prevented in mice, therefore it may provide clues to potential causes, therapies and preventative measures in human epilepsy," said lead researcher Dr Steve Clapcote.
The enzyme regulates the levels of sodium and potassium in the brain's nerve cells. "An imbalance of sodium and potassium levels has long been suspected to lead to epileptic seizures," said Dr Clapcote. "But our study is the first to show beyond any doubt that a defect in this gene is responsible," he added.
Epilepsy charities welcomed the development. Delphine van der Pauw, research and information executive at Epilepsy Research UK, said: "These results are promising. Not only have Dr Clapcote and his team highlighted a new culprit gene for epilepsy in mice but they have also shown how normal activity of the affected sodium-potassium pump can be restored. If the findings can be repeated in human studies, new avenues for the prevention and treatment of inherited epilepsy will be opened.
"The road will be long, we don't even know if any eventual treatment will be safe for humans. But we have taken the first step and it is a big step. This is a very exciting development."
Research has already begun on how the gene defects affect humans. "The human ATP(12A)3 gene matches the mouse version of the gene by more than 99 per cent, so we've already started to screen DNA samples from epilepsy patients," said Dr Clapcote.
Ms van der Pauw added that not all cases of epilepsy are caused by genetic disorders. "Epilepsy can be caused by brain trauma as well as a number of other things. But if it is shown that this gene is the cause of a lot of the cases in humans, then we would support genetic screening being made available on the NHS, even if it is unlikely.
"Epilepsy is already quite low down on the Government's list of funding priorities and there is a stigma attached to the condition. Anything which helps remove that is good news."
Simon Wigglesworth, deputy chief executive of Epilepsy Action, agreed that while it was too early to say whether the treatment would work on humans, it was nevertheless "encouraging news".
He said: "At the moment there is no treatment to cure epilepsy, other than surgery, which is only effective for small numbers. Epilepsy Action welcomes any research which may have positive implications for people with epilepsy."
Current drug treatments are ineffective in around one third of epilepsy patients – an estimated 150,000 people in Britain.