The invention provides a method and system combining functional genomic and genetic, proteomic, anatomic neuroimaging, functional neuroimaging, behavioral and clinical measurements and data analyses for autism pediatric population screening, diagnosis or prognosis. More specifically, the invention provides a weighted gene and feature test for autism which uses a weighted gene signature matrix for comparison to a reference database of healthy and afflicted individuals. The invention also provides normalized gene expression value signatures for comparison to a reference database. The invention additionally combines either the weighted gene or the normalized gene analysis with comparisons to a gene-networks signature matrix, a multi-modal signature matrix, and a collateral features signature matrix for improved accuracy in screening, diagnostic and prognostic relevance for autism, particularly for newborns, babies ages birth to 1 year, toddlers ages 1 to 2 years, toddlers ages 2 to 3 years and young children ages 3 through 4 years.