Studies Map Autism Gene Expression Across Brain Development
Now that genetic studies have implicated several hundred genes in autism, researchers are turning their attention to where and when in the healthy young brain these genes are expressed. The first two studies to tackle these questions appear today in Cell.
One report, led by Matthew State at the University of California, San Francisco, analyzed nine genes that sequencing studies had strongly linked to the disorder. These genes tend to be expressed together in certain layers of the cortex in the fetal brain, the study found.
The second study, led by Daniel Geschwind at the University of California, Los Angeles, took a broader approach, looking at the expression patterns of hundreds of autism-linked genes. Some of these genes tend to be expressed together in networks related to the workings of the synapse, or junction between neurons. Other networks are involved in turning genes on or off.
Despite using different methods, both studies found clusters of autism genes that are important during mid-fetal development, and for the function of neurons that produce the chemical messenger glutamate. These so-called ‘glutamatergic neurons’ mediate excitatory signals in the brain.
"It's remarkable that, despite these huge differences in how we approached the problem, we converged on the same time period and on glutamatergic neurons," Geschwind says. "The themes that are emerging from these analyses are very, very resonant with each other. It's a good thing when that happens in biology."
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