Autism spectrum disorders (ASDs) are neurodevelopmental disorders in which individuals have disrupted social communication and repetitive stereotyped behaviors, which lead to life-long difficulties. Approximately 1 percent of individuals in Asia, North America and in Europe have an ASD, which demonstrates the need to better understand these disorders, and find effective treatments to improve quality of life. In this regard, one of the key discoveries in recent years is that a person's genetic blueprint plays a very important role in risk for ASDs. This means there are genetic risk factors for ASD, and by understanding how these genes cause abnormal brain development, we will better understand the origins of ASDs to develop better treatments. In the current grant, using an integrated approach, we propose to study the TAO2 gene, which is either missing or duplicated in individuals with ASD. Our group is already collaborating with the Autism Sequencing Consortium to discover new mutations in TAO2 that may cause ASD, which will help in the future development of more accurate genetic diagnoses of ASDs. We will complement this genetic approach with cellular and molecular studies to better understand the normal function of TAO2 in the development of brain connections and autism-related behaviors in mouse models. Additionally, we will determine how mutations in TAO2, found in ASD individuals, may contribute to abnormal brain connectivity. We aim at studying the exciting possibility that another ASD-linked gene named FMR1 may control the function of TAO2. We believe this will lead to the identification of a new autism genetic pathway that ultimately would allow discovering drugs that through TAO2 modulation would ameliorate deficits observed in patients with ASD. Ultimately, we believe our studies will be very important not only to understand how TAO2 regulates brain function but also how it may be causative of ASDs via the novel FMRP-TAO2 genetic path.