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= Genetic risk for autism stems mostly from common genes =

Autism is thought to be caused by an interplay of genetic and other factors, including environmental forces, consensus on their relative contributions and the outlines of its genetic architecture has remained elusive, until now. With this new study, the researchers believe that autism genetics is beginning to catch up. The study found that about 52 percent of autism was traced to common genes and rarely inherited variations, with spontaneous mutations contributing a modest 2.6 percent of the total risk. The research team -- from the Population-Based-Autism Genetics and Environment Study (PAGES) Consortium -- used data from Sweden 's universal health registry to compare roughly 3,000 subjects, including autistic individuals and a control group. The largest study of its kind to date, the team also showed that in-heritability outweighs environmental risk. Now that the genetic architecture is better understood, the researchers are identifying specific genetic risk factors detected in the sample, such as deletions and duplications of genetic material and spontaneous mutations. The researchers -- Population-Based-Autism Genetics and Environment Study (PAGES) Consortium -- said even though such rare spontaneous mutations accounted for only a small fraction of autism risk, the potentially large effects of these glitches make them important clues to understanding the molecular underpinnings of the disorder. Current studies have not been large enough to reveal the many common genetic variants that increase the risk of autism. On their own, none of these common variants will have sufficient impact to cause autism.

References: Carnegie Mellon University. "Genetic risk for autism stems mostly from common genes." ScienceDaily. ScienceDaily, 20 July 2014. . **Carnegie Mellon University**. //Note: Materials may be edited for content and length.//

Trent Gaugler, Lambertus Klei, Stephan J Sanders, Corneliu A Bodea, Arthur P Goldberg, Ann B Lee, Milind Mahajan, Dina Manaa, Yudi Pawitan, Jennifer Reichert, Stephan Ripke, Sven Sandin, Pamela Sklar, Oscar Svantesson, Abraham Reichenberg, Christina M Hultman, Bernie Devlin, Kathryn Roeder, Joseph D Buxbaum. **Most genetic risk for autism resides with common variation**. //Nature Genetics//, 2014; DOI: 10.1038/ng.3039

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