Principal investigator Jonathan Sebat, chief of the Beyster Center for Molecular Genomics of Neuropsychiatric Diseases at University of California, San Diego, said the DNA sequence in some regions of the human genome is quite volatile and can mutate 10-times more frequently than the rest of the genome.
The study, published in the journal Cell, found genes linked to autism and a variety of other disorders have a particularly strong tendency to mutate.
Clusters of mutations or "hotspots" are not unique to the autism genome but instead are an intrinsic characteristic of the human genome, Sebat said.
"Our findings provide some insights into the underlying basis of autism -- that, surprisingly, the genome is not shy about tinkering with its important genes," Sebat said in a statement. "To the contrary, disease-causing genes tend to be hypermutable."
Sebat and colleagues at the Rady Children's Hospital-San Diego and BGI genome center in China sequenced the complete genomes of identical twins with autism spectrum disorder and their parents.
The scientists identified many "germline" mutations -- genetic variants that were present in both twins but not present in their mother or father.
Nearly 600 germline mutations -- out of a total of 6 billion base pairs -- were detected in the 10 pairs of identical twins sequenced in the study and an average of 60 mutations were detected in each child.