Demonstrates that autism, like mental retardation, is a clinical presentation of numerous different diseases, many with genomic underpinnings. In this ground-breaking work, the authors explain in great detail how to clinically diagnose infants, children, adolescents and adults with autistic behavioral features and their psychiatric and neurological work-ups. Fully details the many advances that have occurred in the field within the past 10 years since the last edition was published. Combines the separate research done by autism specialists and neuroscientists and blends these two sources, sorting out the relevant findings and characterizing the many remaining unsolved questions.