Autism is a developmental disorder of brain function.
It has no single cause. Researchers believe that several genes and environmental factors such as viruses and chemicals may contribute to the development of the disorder. Some researchers and parents of children with autism have suggested a link between the MMR vaccine and autism. Often symptoms of autism first appear as children show difficulties or delays in speaking after age 1. Typically children receive the first dose of the MMR vaccine at ages 12 to 15 months.