Finding the right drug for each person with epilepsy, at the right dosage from the point of diagnosis is one of the key aims of our research. An individual’s genetic make-up can affect their risk of developing epilepsy, the consequences of the condition and their response to treatment. There is no doubt that finding the cause of an epilepsy has an impact on diagnosis and management and can provide information on outcome for the individual. It can also mean an end to tests looking for the cause of someone’s epilepsy.
DNA tests and epilepsy
One way of identifying underlying genetic causes of epilepsy is through array Comparative Genomic Hybridisation (aCGH), a specific test that looks at a person’s DNA. Using this test, we want to look for parts of a person’s hereditary material or genome that are missing (deletions) or that are duplicated, causing epilepsy and additional problems such as autism, learning disability or other medical illnesses.
In a small pilot study using aCGH, we have identified an abnormality causing epilepsy in around 10 per cent of people. These are people for whom no cause of epilepsy could be identified through standard tests such as an MRI scan. For example, an aCGH test was carried out recently on a woman with photosensitive epilepsy – photosensitivity is a strongly inherited trait but the genes causing it have yet to be identified. The blood test showed a deletion involving a small number of genes, one of which might be causing her epilepsy.
We can now look at these few genes in a larger number of people with photosensitivity, rather than having to trawl through each person’s entire genome. If one of the few genes in the deletion is proven to be the cause of photosensitive epilepsy, we will have identified a new cause of epilepsy and this will hopefully lead to improved management.
Causes of epilepsy
We hope the aCGH project will narrow down the field of genes that might cause other forms of epilepsy and lead to advances in the understanding and treatment of the condition.
Changes such as deletions or duplications in a person’s genome have recently emerged as an important type of risk factor for epilepsy. Sometimes, such changes have led to the identification of a particular gene, alterations in which are a direct cause of the epilepsy. We are excited by the prospect that this project will identify new causes of epilepsy. Over time, the understanding that this brings may prove to be the best way to find new rational treatments for epilepsy.
Professor Sanjay Sisodiya, head of genetics at Epilepsy Society