90 percent of autism may have a genetic basis, geneticist Stephen Scherer of the University of Toronto and the Hospital for Sick Children in Toronto notes in a February 18th Reuters article. A study on the most extensive findings so far on the genetics of autism by Scherer and researchers from a consortium of 19 nations appears today in Nature Genetics. Entitled Mapping autism risk loci using genetic linkage and chromosonal rearrangements, the five-year study suggests that autism has “numerous genetic origins rather than a single or a few primary causes.” DNA samples from 1,168 families—”the largest cohort yet of ASD families yet assembled”—with two or more autistic children were analyzed.
Two new genetic links that may predispose a child for autism were found:
The study incriminated a gene called neurexin 1 involved with glutamate, a brain chemical previously implicated in autism that plays a role in early brain development, as a possible susceptibility gene for autism. A previously unidentified region of chromosome 11 also was implicated.
Neurexins are “a large family of proteins that act as neuronal cell-surface receptors” (Nature Neuroscience 6, 708 – 716 (2003) ); they and neuroligins have been implicated as having a role in autism. The Nature Genetics study pinpoints neurexin-neuroligin link as “fundamentally important for glutamatergic synaptogenesis and thereby points to “glutamate-related genes as promising candidates for contributing to ASDs.” (Glutamate is a common excitatory neurotransmitter in the central nervous system and plays a crucial role in both memory formation and information processing; “synaptogenesis” refers to the formation of synapses.)
We now have “a pretty decent understanding of what the genetic architecture is looking like in the autism genome,” as Scherer was quoted as saying. Scientists hope that, by figuring out the genetics of autism, they can figure out better ways to diganose it and also develop drugs to treat autism.
- Preliminary results of largest scan of autism DNA information from the University of Pittsburgh Schools of the Health Sciences
- Stanford Q&A: Largest-ever study shows possible genetic links for autism from the Stanford University Medical Center
- Genome scan for familial autism finds two new genetic links from the UCLA Newsroom