A new study published in the July 20 issue of Nature Genetics theorizes that a large number of people with autism spectrum disorder have the disease caused by genes that are common in the general population, rather than rare genes or mutations of genes as previously thought. It has yet to be determined whether more people have autism caused by common genes or by rare genes, but this is an important finding.
An international study led by Carnegie Mellon University's Kathryn Roeder found that 52% of patients had autism that was caused by common genes, and that most did not inherit mutations of the gene. The largest study of this kind to date, the team studied about 3,000 patients in Sweden, including a control group. They found proof that genetics outweigh environmental factors in terms of becoming autistic.
"From this study, we can see that genetics plays a major role in the development of autism compared to environmental risk factors, making autism more like height than we thought - many small risk factors add up, each pushing a person further out on the spectrum," Roeder said.
"These findings could not have happened without statistics, and now we must build off of what we learned and use statistical approaches to determine where to put future resources, and decide what is the most beneficial direction to pursue to further pinpoint what causes autism," Roeder added.
Until now, the causes of autism have remained opaque. But this study is a big step in finding the cause, and possible treatment for autism. The study suggests that although environmental factors contribute to autism, the environment is far less important than the genetics when it comes to developing autism.
Joseph Buxbaum, the study's first author and a professor of psychiatry and neuroscience at the Icahn School of Medicine at Mount Sinai, explains that a family may have a common variant that puts it at risk for autism spectrum disorder, but if an individual within the family has a "de novo" mutation in addition, he or she is even more at risk.
Roeder said, "Our group in Pittsburgh is working to develop a model that predicts the genetic risk for a family based on a myriad of small effects. Such a score could provide clinical benefit to families."
