US researchers identify gene network linked to autism

U.S. scientists have identified a molecular network of genes known to contribute to autism spectrum disorders, and they say their finding may help uncover new genes linked to these conditions.

"The study of autism disorders is extremely challenging due to the large number of clinical mutations that occur in hundreds of different human genes associated with autism," study author Michael Snyder, genetics and personalized medicine professor at Stanford University, said in a news release. "We therefore wanted to see to what extent shared molecular pathways are perturbed by the diverse set of mutations linked to autism in the hope of distilling tractable information that would benefit future studies."

According to the news release, researchers used gene expression data and genome sequencing to study the whole set of interactions within a cell, and they identified a module comprised of 119 proteins linked to autism genes.

The sequencing of the genomes was present in 25 study participants who had been diagnosed with autism, which confirmed the involvement of the module in autism. The autism candidate genes in the module were also present in more than 500 diagnosed patients who were analyzed by exome sequencing.

Researchers also found that the corpus callosum and oligodendrocyte cells in the brain can contribute to autism.  Oligodendrocytes are myelin-forming cells of the central nervous system, and the corpus callosum is a huge band of myelinated fibers. Myelin, which is comprised of proteins and phospholipids, forms a sheath around nerve fibers and increases the speed at which impulses are conducted.

"In the future, we need to study how the interplay between different types of brain cells or different regions of the brain contribute to this disease,” study author Jingjing Li, postdoctoral fellow at the Stanford Center for Genomics and Personalized Medicine, said in the news release.

Snyder said the module enriched in autism had two distinct components that exclusively interacted with each other: one that was expressed throughout different regions of the brain, and another that had enhanced molecular expression in the corpus callosum.

Based on their findings, the study authors hypothesized that disruptions in parts of the corpus callosum interfere with the circuitry that connects the two hemispheres of the brain, resulting in autism.

"Our study highlights the importance of building integrative models to study complex human diseases," Snyder said.

The research is published Tuesday in the journal Molecular Systems Biology.