Epidemiology
Etiology
- Males > Females (4:1 ratio).
- Strong genetic component (high concordance in monozygotic twins).
- Risk Factors: Advanced paternal age, maternal use of valproate, low birth weight.
- Associations: Fragile X syndrome, Tuberous Sclerosis, Rett syndrome (though Rett is a distinct entity).
Pathophysiology
Clinical features
- Social communication deficits: Poor eye contact, absent joint attention (no pointing by 18 mo), lack of social reciprocity. c
- Restricted/repetitive behaviors: Hand-flapping, lining up toys, echolalia, rigid adherence to routines, sensory hypo-/hyperreactivity.
- 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.
Treatment
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