Tuesday, July 05, 2011

Genetic Component of Autism Spectrum Disorders May Be Moderate Compared to Environment, Twin Study Suggests

ScienceDaily (July 4, 2011) After evaluating twin pairs in which at least one child has autism or autism spectrum disorder (ASD), researchers suggest that the shared environment may play a more substantial role in development of the condition than shared genes do, according to a report published Online First by Archives of General Psychiatry, one of the JAMA/Archives journals.Current estimates suggest that 40 of every 10,000 children have autism, and prevalence rates for ASDs are about 1 percent, according to background information in the article. Studies of siblings have found a concordance rate (the likelihood that if one child has the disorder, others will as well) of up to 14 percent. The authors note that in previous studies of twins, concordance rates for autism were relatively high for identical (monozygotic) twins, but nonexistent for fraternal (dizygotic) twins. Further, studies that depended on differing methods of diagnosis have resulted in a broad range of estimates of autism's heritability. "However," the authors state, "none of these more recent studies included structured clinical assessments by both parental interview and direct child observation, which is the contemporary standard for establishing the diagnosis of autism or ASD."

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