Core Domain 1: Persistent deficits in social communication & interaction (all 3 required):
Deficits in social-emotional reciprocity (abnormal social approach, failure of normal back-and-forth conversation, reduced sharing of interests/emotions).
Deficits in nonverbal communicative behaviors (poor eye contact, lack of facial expressions, absent pointing/gestures). c
Deficits in developing, maintaining, and understanding relationships (difficulty adjusting behavior to social contexts, absence of interest in peers, lack of imaginative/shared play).
Core Domain 2: Restricted, repetitive patterns of behavior, interests, or activities (≥2 required):
Stereotyped or repetitive motor movements, use of objects, or speech (e.g., hand-flapping, body rocking, lining up toys, echolalia, idiosyncratic phrases).
Insistence on sameness, inflexible adherence to routines, or ritualized patterns (extreme distress at small transitions/changes). c2
Highly restricted, fixated interests abnormal in intensity or focus.
Hyper- or hyporeactivity to sensory input (aversion to specific sounds/textures, apparent indifference to pain/temperature, visual fascination with lights/movement).
Exam: Early childhood macrocephaly (~20%), intellectual disability (~30–50%).
Diagnostics
Initial / Screening:
General developmental surveillance at all well-child checks (9, 18, and 30 months).
ASD-specific screening tool: M-CHAT-R/F (Modified Checklist for Autism in Toddlers) at 18 and 24 months.
Confirmatory / Gold Standard:
Comprehensive multidisciplinary clinical evaluation using DSM-5 criteria (supported by standardized assessment tools: ADOS-2, ADI-R).
Mandatory First Step in Workup:
Audiology / Formal Hearing Evaluation: Must be performed in all children with delayed speech or failure to respond to name to rule out sensorineural/conductive hearing loss before diagnosing ASD.
Adjunctive Testing:
Genetic testing: Chromosomal Microarray (CMA) and/or Fragile X (FMR1) DNA analysis for all unexplained ASD cases.
EEG: Indicated only if clinical seizures are suspected or if there is developmental regression (to rule out Landau-Kleffner syndrome).
Lead screening: If pica or environmental risk is present.