Autism Spectrum Disorder (ASD) is a condition that causes difficulties with social interactions and communication, and unusual or intense behaviours. In most cases, the cause is unknown; however, there is evidence that the cause is likely genetic. We are using a new method to discover genes for ASD in families by looking at how features of ASD are inherited. Discovering genes for ASD will aid the development of new therapies and help parents of children with ASD with family planning.