Core symptoms of
are qualitative impairments for chronological age in social communication ( both verbal & non-verbal) & reciprocal social interaction + repetitive stereotyped, non-functional movements &/or narrow, restricted areas of interest.
. Firstsigns.Org has checklists to screen for developmental delays & autism in infants & toddlers. "red flags" for all ages are on www.Aap.Org's healthy child.