Researchers Look into Potential Cause of Autism Through Brain Examination

Researchers from the University of North Carolina believe they may have found some clues into the brain development of those with autism.

"Our study shows the magnitude of what can happen if topoisomerases are impaired," senior study author Mark Zylka, PhD, said, via a press release, an associate professor in the Neuroscience Center and the Department of Cell Biology and Physiology at UNC. "Inhibiting these enzymes has the potential to profoundly affect neurodevelopment -- perhaps even more so than having a mutation in any one of the genes that have been linked to autism."

The study looked at important implications when it comes to detecting and preventing autism spectrum disorders (ASD.)

"This could point to an environmental component to autism," said Zylka, via a press release. "A temporary exposure to a topoisomerase inhibitor in utero has the potential to have a long-lasting effect on the brain, by affecting critical periods of brain development. "

The study tried to explain why some people with mutations in topoisomerases develop autism and other neurodevelopmental disorders. This is known as an enzyme that's found in all human cells. Its main function is to untangle DNA when it comes to overwound, a common occurrence that can interfere with key biological processes.

"If there are additional compounds like this in the environment, then it becomes important to identify them," said Zylka, via the release. "That's really motivating us to move quickly to identify other drugs or environmental compounds that have similar effects -- so that pregnant women can avoid being exposed to these compounds."

Zylka and colleagues looked to discover almost by accident topotecan, a topoisomerase drug that helps to is used in chemotherapy. During this investigation, they noticed that the drug tended to interfere with proper functioning of genes that were exceptionally long and composed of DNA base pairs. This made the group reach the decision that many autism-linked genes are long.

"That's when we had the 'Eureka moment,'" said Zylka. "We realized that a lot of the genes that were suppressed were incredibly long autism genes."

The study concludes the following, via the release: "Of the more than 300 genes that are linked to autism, nearly 50 were suppressed by topotecan. Suppressing that many genes across the board -- even to a small extent -- means a person who is exposed to a topoisomerase inhibitor during brain development could experience neurological effects equivalent to those seen in a person who gets ASD because of a single faulty gene.

"The study's findings could also help lead to a unified theory of how autism-linked genes work. About 20 percent of such genes are connected to synapses -- the connections between brain cells. Another 20 percent are related to gene transcription -- the process of translating genetic information into biological functions. Zylka said this study bridges those two groups, because it shows that having problems transcribing long synapse genes could impair a person's ability to construct synapses."

"Our discovery has the potential to unite these two classes of genes -- synaptic genes and transcriptional regulators," said Zylka. "It could ultimately explain the biological mechanisms behind a large number of autism cases."

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More information regarding the study can be found via the journal Nature.