The genetics of autism are intensely complicated, but new research may play a pivotal role in unraveling autism’s Gordian knot. Researchers at the University of California, Los Angeles investigated how genes can mutate during the development of the fetal brain. The results revealed that autism is not the cause of the unique structure of brains with autism spectrum disorders (ASD), but the symptom of genetic mutations. These findings have major implications for future research into the genetic causes of autism.

Using an online atlas called BrainSpan, the research team was able to map gene activity in the developing fetal brain. They paid particular attention to gene expression, the process by which genes copy data from DNA to RNA to form proteins. They found that, as the brain develops, it is at highest risk for an autism-related genetic mutation when the cells define their future roles in neural circuits. These changes in cell development affect the brain’s wiring and change how neurons transmit signals.

They also found that the mutated genes cause interference in neural communication between the brain’s layers and hemispheres, which corroborates what other studies in the neurophysiology of autism have found.

“Our findings suggest that the mutated genes caused the miswiring; it’s not a result of having the disease itself,” stated lead study author Dr. Daniel Geshwind, professor of neurology at the David Geffen School of Medicine at UCLA and professor of psychiatry at the Semel Institute for Neuroscience and Human Behavior.

Another key discovery was that autism spectrum disorders and intellectual disability are, in fact, distinct disorders. Although they have common risk genes, this study found that the gene expression is different.

The researchers believe that these findings will be instrumental in opening up research into the biology of ASD. Their next step will be to do genome sequencing to identify more mutations linked to autism and intellectual disability. The researchers have made their data public so that other teams can build on their findings.

“Identifying gene variants that boost risk is only the first step of unraveling a disease. We need to figure out where genetic changes appear in the brain, at what stages during development and which biological processes they disrupt. Only then will be understand how mutations cause autism,” explained Dr. Geschwind.

This research is published in the journal Cell.

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