Transcriptomic Analysis of Autistic Brain Reveals Convergent Molecular Pathways

Published May 25, 2011 in Nature

A study found surprising consistency in molecular changes seen in the brains of people with autism across the spectrum, suggesting a common biological basis that may span multiple subtypes. Researchers analyzed postmortem brain tissue and found atypical patterns of gene expression common to many of the individuals with ASD. These findings may provide clues about how autism changes the brain at the molecular level, and lead to new avenues for developing treatments. In the study researchers focused on gene expression — the way information from the gene is used in the synthesis of functional gene products, often proteins. These proteins then perform specific tasks in the cell. In brains affected by autism, genes involved in neuron function and communication were expressed at much lower levels than in typically developing individuals, and the expression of genes involved in certain immune functions was abnormally high. The authors note that many of these genes are active during fetal development, supporting the theory that abnormal brain development may start very early in the womb. The findings also provide evidence that molecular changes in neuron function and communication are probably a cause of autism, rather than a result of the disorder. To identify common patterns of gene expression among people with autism, the researchers compared the frontal and temporal lobes of the brain – the frontal lobe is responsible for higher-level thinking including judgment and social response, while the temporal lobe plays a key role in hearing and language and is also involved in sensory integration. They found that more than 500 genes were expressed at different levels in the frontal and temporal lobes of typically developing individuals, as would be expected in separate brain regions with differing functions. However, there was almost no difference in the levels of gene expression between the two regions in the brains of those with ASD. This blurring suggests a failure to differentiate regions in early brain development.

–IACC 2011 Summary of Advances in ASD Research

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