WEDNESDAY, May 25 (HealthDay News) -- The symptoms and severity of autism vary widely, but new research shows remarkable similarities at the molecular level in the brains of people with the disorder.
Researchers from Los Angeles, Toronto and London analyzed post-mortem brain tissue samples from 19 people with autism and 17 without.
In the healthy brains, researchers saw distinct differences in the gene expression in the frontal lobe vs. the temporal lobe of the cerebral cortex -- differences that help determine the structure and function of the two brain regions.
Specifically, between the frontal and temporal lobes in the healthy brains, more than 500 genes were expressed at different levels. Gene expression is the process by which a gene's DNA sequence is copied into RNA to produce proteins, which perform specific tasks within the cell.
But researchers didn't find those same patterns in autistic brains. Instead, researchers found only eight differences in the gene expression in the frontal and temporal lobes.
"In a healthy brain, the frontal and temporal lobes can be differentiated," said principal investigator Dr. Daniel Geschwind, a distinguished professor of neurology, psychiatry and human genetics at the David Geffen School of Medicine at UCLA. "But in autism we didn't see that. Instead, the frontal lobe closely resembles the temporal lobe."
Many of those regional differences in the cerebral cortex are established during fetal development, researchers added.
The study is published in the May 25 online issue of Nature.
Over the past decade, researchers have discovered lots of gene variants that seem to play a role in some cases of autism, but none of the mutations were present in a large percentage of people with the disorder.
Prior research has also implicated regions of the cerebral cortex, which is highly developed in humans,
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