Autism Spectrum Disorder (ASD): Current Understanding of Causes

Autism Spectrum Disorder (ASD) is a neurodevelopmental condition with no single cause. Research points to a complex interplay of genetic and environmental factors.

Genetic Factors (Major Contributors)

• Heritability estimates: 70–90% (twin studies).
• Hundreds of risk genes identified (synapse formation, chromatin remodeling, neurodevelopment).
• Both common variants (polygenic) and rare de novo mutations (CNVs, SNVs) contribute.
• Recurrence risk: ~10–20% for siblings; higher if multiple affected relatives.
• Syndromic ASD: Fragile X, Rett, Tuberous Sclerosis, Phelan-McDermid, etc.

Environmental Factors (Modest, Modulatory)

• Prenatal: Advanced parental age (esp. paternal), maternal infection/fever, valproate exposure, gestational diabetes, preeclampsia, prematurity/low birth weight.
• Perinatal: Birth complications, hypoxia, neonatal encephalopathy.
• Postnatal: No credible evidence for vaccines, parenting style, or diet as causes.
• Epigenetic mechanisms likely mediate gene-environment interactions.

What Is NOT a Cause

• Vaccines (MMR, thimerosal) – extensively debunked.
• "Refrigerator mother" theory – harmful, false.
• Single gene or single environmental toxin.

Ongoing Research

Focus areas: gene networks, early biomarkers, gut-brain axis, immune dysregulation, and personalized intervention timing.

ASD is a different neurodevelopmental trajectory—not a disease to cure, but a condition to understand and support.