Now the experiments to find de novo variants for epileptic encephalopathies within the Euroepinomics RES-project are well underway and first data are coming out, it is a good moment to pause and think about what results we can expect, and how these should be interpreted. For this it is very nice that recent large experiments in autism have provided so much useful data. In this post, I will explore what we can expect in experiments in which we perform whole exome sequencing in a group of patients and their parents to identify de novo variants that could be the cause of the disorder.