Autism, researchers agree, is caused by a mix of genetic and environmental factors. At this point, however, consensus dissolves. Views differ, sometimes dramatically, over the degrees of risk that should be associated with specific factors—and how multiple factors should be added together to better account for how autism occurs.
A key challenge has been harmonizing the different kinds of studies that have been conducted, particular the different kinds of genetic studies, some of which have focused on rare variants, some of which have focused on common variants. Differences in methods and statistical models have resulted in sometimes wildly discrepant estimates of autism’s heritability—ranging from 17 to 50%.
Recently, evidence has been mounting that genomes of people with autism are prone to harboring rare mutations, often spontaneous, that exert strong effects and can largely account for particular cases of disease. More challenging is to gauge the collective impact on autism risk of numerous variations in the genetic code shared by most people, which are individually much subtler in effect.
Read the full, original story: Genetic Risk for Autism Mostly Due to Common Gene Variants