People with autism show differences from controls in the levels of microRNAs, small noncoding bits of RNA, in the social and sound-processing parts of the brain. Unpublished results from the postmortem study were presented Wednesday at the 2013 Society for Neuroscience annual meeting in San Diego. MicroRNAs, or miRNAs, bind to messenger RNAs, which code for protein, and flag them for degradation. Each miRNA can interfere with the production of several proteins. For example, a 2011 study linked the lack of miR-125a to denser dendritic spines, the signal-receiving branches of neurons, and to higher levels of postsynaptic density-95, a protein associated with autism. Postmortem brain studies have shown that some miRNAs are expressed differently in the brains of people with autism.
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