Autism has been mostly linked to faulty genes or mutations. A new study shows that common gene variants are responsible for a number of genetic risks for autism.
According to the researchers, their study showed that almost 52 percent of autism risk was due to common and rare inherited variations. Spontaneous mutations accounted for just 2.6 percent of the total risk, the researchers found.
"Genetic variation likely accounts for roughly 60 percent of the liability for autism, with common variants comprising the bulk of its genetic architecture," researcher Joseph Buxbaum of the Icahn School of Medicine at Mount Sinai (ISMMS) said in a press release. "Although each exerts just a tiny effect individually, these common variations in the genetic code add up to substantial impact, taken together."
For the study, researchers compared samples of 3,000 autistic and healthy people. The team was able to evaluate their results with a parallel study in 1.6 million Swedish families, which looked into the data of twins and cousins, and considered factors such as age of the father at birth and parents' psychiatric history.
"This is a different kind of analysis than employed in previous studies," Thomas Lehner, chief of NIMH's Genomics Research Branch, said. "Data from genome-wide association studies was used to identify a genetic model instead of focusing just on pinpointing genetic risk factors. The researchers were able to pick from all of the cases of illness within a population-based registry."
Researchers said that they were planning to identify specific genetic risk factors detected in the sample, such as deletions and duplications of genetic material and spontaneous mutations.
"Within a given family, the mutations could be a critical determinant that leads to the manifestation of ASD in a particular family member," Buxbaum said. "The family may have common variation that puts it at risk, but if there is also a de novo [spontaneous} mutation on top of that, it could push an individual over the edge. So for many families, the interplay between common and spontaneous genetic factors could be the underlying genetic architecture of the disorder."
The findings were published in the journal Nature Genetics.
