Woud you please discuss the clinical aspects of autism spectrum disorder?

Many signs: Autistic spectrum disorder or ASD is notable in many signs: failure to interact with the world around; repetitive hand or body movements; delayed speech, sometimes with echolalia -- repetitive speech patterns. Most ASD can be noted by about 12-18 months of age. Developmental eval by pediatrician or ped neurologist can be helpful. There is another form in which development regresses.