Genes and Autism: New Challenges Ahead

A new twin study of autism suggests that while genetics clearly play a key role , environmental factors are influential too – and in fact may be as important important.

This work – which involved analysis of twins in a large national database in Sweden – partially replicates a recent twin study of autism with US twins sample published in 2011. The only difference is the US study found evidence of “shared environmental” influences on autism – environmental factors that partially explain the similarity of twins (or siblings) independent of genetics. But in both cases, the heritability estimate (a statistical, not biological, metric) suggests that the sum effect of genes on autism is less than estimated in the past.

Overall, the implication is that we need to ramp up efforts to examine environmental contributions to autism – without diluting genetic research. This is easier said than done in a climate in which research funding continues to retract. The reduction of funding makes it harder to pursue the complex issues that require sorting out. Here’s a sampling of issues requiring further intensive investigation:

  • It is likely that there is no one “cause” of autism, such that there may be subtypes that are more strongly effected by genes than others. Testing out this idea would require very large samples – which requires substantial funding.
  • Isolating multiple genes that have “small effects” rather than finding one “disease gene” is still a tricky proposition (akin to looking for multiple needles in a haystack). Researchers continue to evolve biological and statistical approaches to achieve this – but again this work is costly.
  • The same complexities characterize efforts to isolate environmental contributors to autism. Bear in mind that the twin studies don’t identify the sources of the environmental effect – rather, they provide evidence suggesting that environmental factors are critically important and should not be ignored. Again – funding is needed for this.

As the estimated rate of autism continues to climb, and the science keeps telling us that the causes are varied and complex, we need to embrace the idea that funding is critical. Yet we continue to hear that funding for autism research is limited at the national level. Private organizations like Autism Speaks are making great strides but the effort required necessitates a national commitment to increase funding for research on autism. Disseminating that perspective to law makers is one way to try to provide the level of support necessary to examine the roots of a disease that affects more and more children each year.

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Early Signs of Autism
Early Signs of Autism
Early Signs of Autism

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