mTOR is a critical effector of cell signaling, playing a pivotal role in regulating physiology of the whole body, including the brain. Mutations in genes encoding GATOR1 complex, an inhibitor of mTOR activity, have been recently implicated in the pathogenesis of a wide spectrum of focal epilepsies (FEs), occasionally associated with malformations of cortical development. Loss of mTOR inhibitor activity is the hypothesized mechanism underlying epilepsy. In this review, the authors summarize the current knowledge about GATOR1 mutations in FEs, and discuss the future therapeutic opportunities for patients. (By Sara Baldassari, http://jmg.bmj.com/content/early/2016/05/19/jmedgenet-2016-103883 )