An international consortium of autism researchers, including two from Vanderbilt, has reported a significant advance in unraveling the genetics of autism spectrum disorders (ASD).
Reporting in the June 9 issue of the journal Nature, the researchers compared the DNA obtained from nearly 1,000 people with ASD to nearly 1,300 matched controls (people without ASD). They found that people with ASD tended to have more rare copy number variations (CNVs), deletions or duplications of specific sections of DNA that may affect gene expression.
“Our work has identified numerous genes with variants that cause or contribute substantial risk to carriers, but the CNVs identified were very rare,” says James Sutcliffe, associate professor of molecular physiology, biophysics and psychiatry at Vanderbilt. “The number of different genes affected is large, and this further underscores the genetic complexity of ASD.”
“The genetics of autism has been very difficult to understand. It is heartening that we are now beginning to make progress and that this will open the door to further research in understanding the genetic underpinnings of autism,” adds Jonathan Haines, the T.H. Morgan Professor of Human Genetics, professor of molecular physiology and biophysics, and director of the Vanderbilt Center for Human Genetics Research, who also participated in the research. Both are Vanderbilt Kennedy Center investigators.
Autism is a spectrum of developmental disorders characterized by impairments in communication and social interaction, and patterns of repetitive, restricted and stereotyped behaviors. It occurs in up to one in every 150 children in the United States, and is more common in males.
Most studies to date have focused on common genetic variation, which causes only slight increases in risk. The findings reported in this study add to a growing body of evidence that suggests ASD is caused in part by many rare variants impacting numerous biological pathways. Some of these variants may affect genes involved in transmitting signals between nerve cells in the brain, while others previously have been implicated in intellectual disabilities.
Identification of these rare variants and the biological pathways they may affect was made possible by the international Autism Genome Project, which recruited a large number of research participants throughout the world.
The project is opening up new areas of research and new targets for genetic testing, the researchers concluded. Potentially, these studies could lead to the development of new treatments for ASD.