 Autism is a neurodevelopmental disorder that results in abnormalities of social and language development and is associated with rigid and repetitive behaviors. Although there is strong evidence of heritability, the involved genes have not been identified. The prevalence of autism spectrum disorders may be as common as 1 in 166. The average concordance rate in monozygotic twins is 70 suggesting that environmental factors play a role in the disease. Subgroups of autistic children seem unusually sensitive to infections, immunizations and dietary factors, but none of these factors has been causally identified with the disease. Nevertheless, autoimmunity has been considered to play a role on the basis of indirect evidence. There is no evidence-based efficacious treatment for autism. 