The objective of this project is to improve our understanding of the molecular and genetic basis of autism, which will lead to an earlier, more accurate diagnosis and possibly the treatment of Autism Spectrum Disorders (ASD). Not only is dystrophin highly expressed in skeletal muscle and cardiac muscle, but also restricted regions of the brain. Coincidentally, a significant number of DMD patients also have significantly reduced IQ scores and meet the diagnostic criteria for ASD. Due to the expression of dystrophin in the brain, specifically the Purkinje cells located in the cerebellum, we hypothesize that dystrophin plays a role in ASD. Using diverse neurobehavioral assays, we have shown that our dystrophin-deficient mouse models (the mdx and the mdx5cv) with observed evidence of Purkinje cell dysfunction, exhibit behavioral symptoms of impaired social approach similar to that seen in human patients. This has leaded us to identify several chemical compounds that ameliorate this social-behavioral phenotype in our dystrophin-deficient mice. We plan to test additional strains of DMD mice including a conditional null of dystrophin in just the Purkinje cells.