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Study Provides ‘Formula’ for Predicting Effects of Autism-linked Genes

 

Researchers funded by Autism Speaks have helped devise a “genetic formula” that promises to improve the accuracy of early screening for autism and speed the identification of biological targets for future treatments.

The report appears online in Nature Genetics.

“This study provides new insights into the unique ways genetic risk factors for autism are expressed in the brain,” says Robert Ring, Autism Speaks chief science officer. “This knowledge helps to lay the foundation for turning genetic discoveries into diagnostic tests that will detect autism earlier, and opens the door to the future personalization of medical or behavioral interventions in autism.”

Recent advances in genome sequencing technology have led to the rapid identification of hundreds of gene changes associated with increased risk of autism. The challenge has been to determine how much risk comes with individual gene variations. Indeed, many individuals carry multiple autism-risk genes without ever developing autism.

Lead author Mohammed Uddin, a computer scientist, determined that the key to solving the puzzle resides in recognizing whether an autism-linked DNA change affects the “exon” of a gene involved in brain development. In essence, exons are a gene’s active components. Their DNA spells out the directions for building proteins. In genes associated with autism, these proteins are generally involved in brain-cell development and communication.

In all, the Toronto team identified almost 4,000 exons in more than 1,700 genes affecting brain development. Early brain development depends on these exons “switching on” inside brain cells at just the right time and place.

“The fact that these genes could be turned on prenatally gives us a clue as to when autism starts to develop,” says senior investigator Stephen Scherer. Dr. Scherer directs the Centre for Applied Genomics at Toronto’s SickKids Hospital and the University of Toronto. His pioneering work in autism genetics is funded by several Autism Speaks research grants.

“With this study, we’ve finally discovered a unifying set of characteristics in the DNA that we can weave into a ‘genetic formula’ that helps calculate which genetic mutations have the highest probability of causing autism,” Dr. Scherer says. “Equally important, these findings also indicate which gene alterations do not play a role.”

The study’s co-authors also included Ryan Yuen, whose research is supported by an Autism Speaks Meixner Postdoctoral Fellowship in Translational Research. Other study funders included the University of Toronto, NeuroDevNet, Genome Canada and the Ontario Genomics Institute, the Canadian Institutes for Health Research, the Canadian Institute for Advanced Research, the Canada Foundation for Innovation, the government of Ontario, the Ontario Brain Institute and the SickKids Foundation.