The central aim of this project is to characterize the expression of exosomal microRNA (miRNA) in children with autism spectrum disorder (ASD). Currently, the CDC estimates the prevalence of ASD in U.S. children to be 1 in 68. Yet, the biological causes, diagnosis, and treatment of this disease remain ambiguous. Growing evidence implicates a genetic role in ASD. miRNAs regulate genetic expression and are altered in lymphocytes, neurons and serum of patients with ASD. Recent studies of miRNAs have shown that they can be packaged into exosomal vessels and extruded from neurons as extracellular signaling tools. This knowledge provides a novel approach for examining the genetic regulation of the central nervous system.