Some research on Autism involving genetics and environmental factors

I think I started trying to find the evidence linking MTHFR with Autism and came across some interesting studies suggesting that a combination of genetic and environmental factors (including toxin exposure and/or nutrient deficiency) might be one model for the development of Autism. Obviously if Autism had a simple, single cause it seems almost certain that it would have been identified. More complex models are more difficult to study but ultimately essential to our understanding.

  • “The rise in prevalence of autism spectrum disorders (ASD) is suggestive of a new etiology. Diagnostic substitution alone is unlikely to account for the increase, while genetic association with detoxification gene alleles points to an environmental contribution. Subtle structural anomalies in the ASD brain are widespread but limbic damage seems important for the development of behaviors diagnostic of ASD… A two-hit combination of genetic susceptibility and environmental challenge is argued to underlie the rise in ASD.”
  • “Adjusting for sociodemographic factors and maternal smoking, maternal residence at the time of delivery was more likely be near a freeway (≤ 309 m) for cases than for controls… Autism was also associated with residential proximity to a freeway during the third trimester… After adjustment for socioeconomic and sociodemographic characteristics, these associations were unchanged. Living near other major roads at birth was not associated with autism.”
  • “Mothers of children with autism were less likely than those of typically developing children to report having taken prenatal vitamins during the 3 months before pregnancy or the first month of pregnancy… Significant interaction effects were observed for maternal MTHFR 677 TT, CBS rs234715 GT + TT, and child COMT 472 AA genotypes, with greater risk for autism when mothers did not report taking prenatal vitamins periconceptionally… Greater risk was also observed for children whose mothers had other one-carbon metabolism pathway gene variants and reported no prenatal vitamin intake.”
  • The study sample of 85 176 children was derived from the population-based, prospective Norwegian Mother and Child Cohort Study (MoBa)… In children whose mothers took folic acid, 0.10%… had autistic disorder, compared with 0.21%… in those unexposed to folic acid. The adjusted OR for autistic disorder in children of folic acid users was 0.61… No association was found with Asperger syndrome or PDD-NOS, but power was limited.

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