This is a supplement to a project funded in 2010 (5P01ES011269-10). Recent studies indicate that immune function in children with autism spectrum disorder (ASD) is profoundly altered compared to developmentally healthy controls. There is a strong interface between the immune system and the neurologic network, and successful neurodevelopment is contingent upon a successful interaction between these two systems. The study is one of three interrelated research projects at the University of California-Davis Center for Children's Environmental Health (CCEH) and will investigate both the serologic and cellular aspects of immune function in patients with autism to try to determine the underlying cellular mechanisms involved. From a cohort of children previously analyzed in the CHARGE study (Childhood Autism Risks from Genetics and Environment), children representing the entire ASD spectrum will be studied to evaluate the longitudinal serologic profile of children with ASD to determine which immune cell population(s) are crucial in the immune dysfunction seen in patients with autism and to fully characterize the autoantibody response in a subpopulation of children with ASD and some mothers of children with ASD.