It has long been recognized that autism runs in families, suggesting a substantial（大量的，实质的） genetic component to the disease. Yet few genes have so far been identified and the underlying genetic architecture of autism -- that is, how many genes contribute and to what extent they influence a person's chances of developing the disorder -- remains poorly understood. Now, a consortium led by researchers from the Broad Institute, Massachusetts General Hospital (MGH), and six other organizations has taken a step toward addressing these questions by searching for mutations in the fraction of the human genome that codes for proteins. The researchers sequenced this region, known as the "exome," in 175 autism patients and their unaffected parents, looking for single-letter DNA changes present only in the children. Their results, along with simultaneously published findings from two other research groups, suggest modest roles for hundreds of genes in the development of autism and pinpoint a few specific genes as genuine（真实的） risk factors. The work is described in a paper that appears online April 4 in the journal Nature.

"Autism, like many heritable disorders, results from the action of many genes -- not simply a single gene as in cystic fibrosis（囊胞性纤维症） or Huntington's disease," said senior author Mark Daly, chief of the Analytic and Translational Genetics Unit at MGH, a senior associate member of the Broad Institute and co-director of its Program in Medical and Population Genetics, and a member of the Broad Institute's Stanley Center for Psychiatric Research. "These genes hold key insights into the true biological causes of autism -- insights we have been unable to gain through other lines of research."

Autism is a common neurodevelopmental disorder characterized by impaired social, behavioral, and communication abilities. Compared to other complex diseases, which are caused by a complicated mix of genetic, environmental, and other factors, autism is highly heritable -- genetics accounts for roughly 80-90% of the risk of developing autism. Yet the majority of autism cases cannot be attributed to known inherited causes.

Researchers in the ARRA Autism Sequencing Collaborative (AASC) -- formed by researchers from the Broad Institute, MGH, Baylor College of Medicine, Mount Sinai School of Medicine, Vanderbilt University, University of Pennsylvania, Carnegie Mellon University, and University of Pittsburgh -- used massively parallel sequencing to help shed light on the genes that influence autism risk. Concordant findings from separate studies by two other groups, from Yale University and the University of Washington respectively, also appear in Nature.