A brief history of autism, the autism/vaccine hypothesis and a review of the genetic basis of autism spectrum disorders.

Autism spectrum disorders (ASD) represent a common spectrum of developmental disabilities, sharing deficits in social interactions, communication and restricted interests or repetitive behaviors with difficult transitions. In this article, we review the history of the identification and classification of autism and the origin of the now widely-debunked autism/vaccine hypothesis. The differences between syndromal (complex) and non-syndromal (essential) autism are described and illustrated with case descriptions where appropriate. Finally, the evidence that autism is fundamentally a genetic disease is discussed, including family studies, the role of DNA copy number variation and known single gene mutations.