Neurodevelopmental disorders affect 3-5% of children but frequently management options are limited by diagnostic imprecision. Often genetic factors are important in their cause but an understanding of which genetic factors contribute to causation is lacking. The condition that we will study for this project is termed periventricular nodular heterotopia, a disorder in which neurons become misdirected in terms of their position in the brain during development. In this project we will use combinations of genome sequencing and cellular studies in induced pluripotent stem cells that have been obtained from patients with these conditions to understand the functional effects of these complex genetic underpinnings for these conditions. We will study newly identified neuronal-specific properties of proteins, in particular our new observation that in neurons some genes adopt new functions exclusive to that cell subtype. Our aim is to bring diagnostic precision to families with neurodevelopmental disorders generally.