Mutations in a number of genes have been shown to cause epileptic encephalopathy, one of the most severe types of epilepsy. Many of these genes control the expression of other genes i.e. they are responsible for switching certain genes ‘on’ or ‘off’ during the development and/or functioning of the brain. Here, we will use a new genome-editing technology to introduce mutations into two of these genes and create neuronal models of epilepsy. We will then study how mutations in these genes disrupt gene expression, and which pathways are affected. Identifying these pathways is the first step in finding new targets for therapeutics and understanding how genetic mutations cause epilepsy.