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Chromosome 5 and Autism

Posted Apr 01 2009 12:00am

Important studies of humans’ genes conducted by a team led by Hakon Hakonarson and Gerard Schellenberg have revealed that individuals with Autism are substantially more likely to have different genetic structures at specific areas on chromosomes than individuals who do not have Autism. Although previous studies of the human genome in Autism had yielded differences of substantial scientific interest, the differences often only accounted for a small percentage of the populations; instead of fewer than 1-3%, these differences may be present in ~15% of cases.

A research team has connected more of the intricate pieces of the autism puzzle, with two studies that identify genes with important contributions to the disorder. One study pinpoints a gene region that may account for as many as 15 percent of autism cases, while another study identifies missing or duplicated stretches of DNA along two crucial gene pathways. Significantly, both studies detected genes implicated in the development of brain circuitry in early childhood.

“Because other autism researchers have made intriguing suggestions that autism arises from abnormal connections among brain cells during early development, it is very compelling to find evidence that mutations in genes involved in brain interconnections increase a child’s risk of autism,” said study leader Hakon Hakonarson, M.D., Ph.D., director of the Center for Applied Genomics at The Children’s Hospital of Philadelphia.

Both studies link material on chromosome 5 with Autism. The research implicates genetic material near locations known as the cadherins (particularly cadherin 10 cadherin 9), neurexins, and ubiquitins. Genetic material in this area affects the creation and eliminate of molecules responsible for adhesion between cells. Neuronal cell-adhesion molecules are important because they affect communication from one nerve cell to neighboring nerve cells.

PDFs of the two studies, “Common genetic variants on 5p14.1
associate with autism spectrum disorders
” and “Autism genome-wide copy number variation reveals ubiquitin and neuronal genes,” are available from Nature. Because I’m not a student of genetics, I’d welcome comments from people who actually know this research area and can explain the concepts and mechanisms.

Read the press release from the The Children’s Hospital of Philadelphia (PA; US); that’s the source of my quotation. Also see coverage by Tina Hesman Seay of Science News, Tina Tsouderos of the Tribune.com carried in the Los Angeles Times.

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