Heritability contributes a large fraction of the risk of a child's developing the disorder

The manifestations of autism cover a wide spectrum, ranging from individuals with severe impairments-who may be silent, mentally disabled, and locked into hand flapping and rocking-to less impaired individuals who may have active but distinctly odd social approaches, narrowly focused interests, and

Also called: Autistic spectrum disorder (ASD), Pervasive developmental disorder (PDD). Autism is a brain development disorder characterized by impairments in social interaction and communication, and restricted and repetitive behavior, all exhibited before a child is three years old. These characteristics distinguish autism from milder autism spectrum disorders (ASD).