Research in my laboratory is focused on studying genetic modifiers that influence the clinical severity of epilepsy. Variable expressivity is a common feature in patients with epilepsy caused by sodium channel mutations, and family members carrying the same mutation often exhibit differences in the clinical severity of epilepsy. Similarly, mouse models with mutations in voltage-gated sodium channels have a variable epilepsy phenotype depending on their genetic background. We use genetic and genomic approaches to identify modifier genes that contribute to phenotype variability in mouse models and also investigate whether the same genes contribute to epilepsy risk in patients. We then use neurophysiological approaches to study the mechanisms underlying phenotype modification. Isolation of epilepsy modifier genes will contribute to our understanding of the molecular basis of epilepsy and may suggest novel targets for improved treatment of human epilepsy.