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(Ivanhoe Newswire) -- Researchers continue to unearth more pieces in the complex autism inheritance puzzle.
A complex combination of multiple genetic duplications and deletions is thought to interfere with gene function, which can disrupt the production of proteins necessary for normal neurological development. The latest study from a research team of geneticists from The Children's Hospital of Philadelphia, the University of Pennsylvania School of Medicine and several collaborating institutions has identified 27 different genetic regions where rare copy number variations missing or extra copies of DNA segments exist in the genes of children with autism spectrum disorders (ASDs), but not in the healthy controls.
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Hakon Hakonarson, M.D., Ph.D., director of the Center for Applied Genomics at The Children's Hospital of Philadelphia and associate professor of Pediatrics at the University of Pennsylvania School of Medicine, and Maja Bucan, Ph.D., professor of Genetics at the University of Pennsylvania School of Medicine and Chair of the Steering committee for Autism Speaks' Autism Genetic Resource Exchange (AGRE) led the study.
"We focused on changes in the exons of DNA -- protein-coding areas in which deletions or duplications are more likely to directly disrupt biological functions," Dr. Hakonarson is quoted as saying. "We identified additional autism susceptibility genes, many of which . . . belong to the neuronal cell adhesion molecule family involved in the development of brain circuitry in early childhood." He added that the team discovered many "private" gene mutations -- those found only in one or a few individuals or families -- an indication of genetic complexity, in which many different gene changes may contribute to an ASD.
"We are finding that both inherited and new ... genetic mutations are scattered throughout the genome, and we suspect that different combinations of these variations contribute to autism susceptibility," Dr. Bucan is quoted as saying."
The researchers compared genetic samples of 3,832 individuals from 912 families with multiple children with ASDs against genetic samples of 1,070 disease-free children.
This study also uncovered two novel genes in which variations were found -- BZRAP1 and MDGA2 -- thought to be important in synaptic function and neurological development, respectively. Interestingly, key variants of these genes were transmitted in some, but not all, of the affected individuals in families.
SOURCE: PloS Genetic, June 26, 2009
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