International Multicentric Observational Study to Characterize Subpopulations of Patients With Autism Spectrum Disorder

Inclusion Criteria: * Participants previously diagnosed with ASD (DSM-5) * Available well-documented health records within the first 2 years of life * Participants must have a parent or reliable caregiver who agrees to provide information about the participant * Participants willing and consenting or assenting to participate. Exclusion Criteria: * Episode of fever (i.e. ≥100.5 °F or ≥ 38 °C) or clinically significant illness without fever (as judged by the investigator), within 10 days before any study assessment. * If the investigator assesses any unwillingness or any medical condition that may prevent the subject from completing this study.