Autism Genome Scan
Although no one knows for sure what causes the various manifestations of Autism Spectrum Disorders, scientists agree that gene abnormalities are associated with most cases of the condition.
Various studies have associated genes on the X chromosome, as well as chromosomes 2, 3, 7, 15, 17, and 22 with ASDs. Most recently, scientists working together through the Autism Consortium have identified an important region on chromosome 16 that appears to account for as many as 1% of cases of ASDs. Both a gene deletion and gene duplication in this same region of chromosome 16 have been associated with a susceptibility to developing an ASD, verified by three collaborating sources. Discovering this region of the genome associated with ASDs opens a pathway to studies of how those genes function. It also illuminates as clearly as anything could that autism spectrum disorder is, indeed, a very complex disease.
The Autism Genome
Many significant advances in biomedical science depend on new technology that enables researchers to answer questions that previously could not be answered. The ability to sequence the human genome by using a combination of computer power and automated instruments that read DNA to reveal the identity and physical location of genes or gene deletions is crucial to unraveling the genetics of autism, just as it was the key technology that enabled scientists to sequence the entire human genome. The autism genome can be thought of as a subset of the human genome. Each cell in our bodies (and we have a trillion cells) contains a complete genome. But each cell is programmed to use some of its genes and not others. It is the genes that contribute to susceptibility to ASDs that constitute the Autism Genome. At the present time, there are a number of genes associated with ASDs on the list. As science advances, some may be removed, if it is determined that they are not related to ASDs after all; others may be added. The recent studies by Autism Consortium scientists on gene deletions and duplications on chromosome 16 are an extremely important addition to the Autism Genome list because they occur in such a large percentage of individuals with ASDs.
Following the Autism Genome
In order to fully understand any genetic condition, identifying genes that either cause a disorder or make someone susceptible to it is only the first step in a long research process that the Autism Consortium's more than 70 scientific experts intend to speed-up through collaboration.
A gene, which is a stretch of DNA that is, in essence, a genetic word, gives a cell the blueprint from which to produce proteins. Genes make proteins; proteins do the cell's work. Therefore, one of the Autism Consortium's next priorities is to study the "functional" role of proteins that are made (or not made) by some 25 genes in the ASD region of chromosome 16. Which proteins work they way they are supposed to? Which do not? How do they interact with other proteins? What cellular pathways do they follow?At this point, the general answer to these questions is "We don't know." However, as Autism Consortium researchers unravel the answers to these questions they will be on the way to identifying "targets" that are likely to be useful for one of two things. First, these targets will help in the development of new DNA tests for children who are seen by physicians for diagnosis. Second, and equally important, protein targets can be useful in designing drugs and other potential treatments.