In simplex cases, it's thought that new variants -- known to scientists as "de novo" variants -- arise spontaneously when the child is conceived and are to blame for the autism disorder, as opposed to variants that are passed from one generation to the next.
The presumption was that by using a higher resolution technology, researchers would turn up more copy number variants, said Andy Shih, vice president of scientific affairs for Autism Speaks.
But researchers didn't find a remarkable increase. In the study, led by researchers at Cold Spring Harbor Laboratory in New York, researchers found de novo events in 8 percent of children with an autism spectrum disorder, compared to 2 percent of the unaffected siblings.
That's relatively consistent with other work in which the range is anywhere from 7 to 20 percent, said Schaaf said, who added that the studies did confirm that children with autism carry de novo copy number variants at a higher frequency than their parents and unaffected siblings.
The researchers also made some intriguing discoveries. In this study and a second one led by scientists at Yale University, researchers found that children with autism were more likely to have copy number duplications on an area of Chromosome 7 known as 7q11.23.
Prior research has shown that deletions on 7q11.23 is associated with Williams or Williams-Beuren Syndrome, a rare disorder in which children are hypersocial and have no inhibitions about talking to strangers, as well as cardiovascular disease and developmental delays.
"That's really interesting," Schaaf sa
All rights reserved