This project will look at the genetic underpinnings of neurodevelopmental traits such as cognitive ability and social and communication difficulties, and the genetics of related conditions such as autism, intellectual disability and ADHD. It is known that both common and rare genetic variants influence these traits. In this project, we will use the extensive longitudinal data in ALSPAC to construct trajectories of neurodevelopmental traits over time, and look at genetic influences on these and whether they are moderated by environmental factors. We will also contribute data to the Autism Sequencing Consortium (ASC), a leading international collaborative group working on deciphering autism genetics and its relation to cognition and brain development. We plan to combine ALSPAC clinical and sequencing data with other datasets of similar nature from the ASC, to identify new genes underlying autism, understand genetic differences between autistic individuals who have different co-morbidities and understand sex differences in autism.