Genomics of drug resistance: moving ahead

Drug resistance is an important clinical problem. Significant efforts have been made recently to improve understanding. Most recently, a Commission of the International League against Epilepsy has produced a document on the definition of drug resistance [1]. This is an important step forward. It must be recognised, however, that the definition of drug resistance may need to be adjusted according to the needs of a particular clinical or research question. Overall, about one in three patients who have epilepsy do not respond to currently available anti-epileptic drugs. Not only is this a significant burden on healthcare systems, but it is also associated with an increased risk of morbidity and premature mortality for patients, as well as a broad range of psycho-social consequences. One can estimate that in the United Kingdom alone, for example, the cost of the first failed anti-epileptic drug is of the order of £20 to £30 million per year. There are of course costs well beyond monetary values. Observational studies have demonstrated that some patients who have not responded to several anti-epileptic drugs in the past, and might therefore be expected to continue to have seizures despite trials of further anti-epileptic drugs [2], might in fact occasionally respond to a new anti-epileptic drug [3, 4].