Chinese scientists have achieved a major advancement in gene therapy for autism, as reported in the journal Nature Neuroscience. This innovative therapy, developed by a research team in Shanghai, has been successfully tested on mice.
The research marks a significant step in the treatment of autism spectrum disorder (ASD) through genetic base editing within the brain.
The therapy involves a genome editing system that has been adept at modifying a specific mutated gene associated with autism spectrum disorder. This mutation was artificially introduced into mice, and the treatment, administered via an injection, led to a notable reduction in ASD-related behaviors in these animals.
This is the first instance of an effective treatment for mice with ASD-related mutations using base editing in the brain.
Autism spectrum disorder, affecting approximately one percent of the global population, is a condition that can significantly impact an individual’s communication and social interaction abilities. It is often accompanied by repetitive behaviors and intense interests.
In the United States alone, one in every 36 children is diagnosed with ASD, according to the US Centers for Disease Control and Prevention (CDC).
The researchers focused on the MEF2C gene, which is strongly linked to ASD. Mutations in this gene are thought to cause developmental deficits, speech problems, repetitive behaviors, and epilepsy.
The male mice in the study, modified to have lower levels of the MEF2C protein in the brain, exhibited symptoms similar to hyperactivity, social interaction difficulties, and repetitive behavior, mirroring ASD-like symptoms.
The exciting development comes on the heels of Britain approving the world’s first CRISPR-Cas9 gene editing therapy for blood conditions like sickle cell disease.
Unlike CRISPR-based systems that work by cutting DNA strands, potentially leading to unintended mutations, the Chinese researchers employed a single-base editing system called AeCBE.
This system offers more precision by working on individual DNA base pairs without creating any cuts, thereby minimizing the risk of unintended genetic alterations.
Professor Li Dali from East China Normal University, who was not involved with this study, noted that this was the first effective treatment of mice with ASD-related mutations using base editing in the brain, according to Shenzhen-based autism media platform Dami & Xiaomi.
To overcome the challenge of delivering the editing system to the brain, the researchers used an adeno-associated virus vector, capable of crossing the blood-brain barrier. The treatment was administered through a single injection into a tail vein of the mutant mice.
The results were promising: the treatment restored MEF2C protein levels in several brain regions and reversed the behavioral abnormalities in the mice.
The editing accuracy rate in the brain cells was found to be around 20%, a percentage sufficient to raise levels of the MEF2C protein. The researchers noted that this editing rate could be even higher in neurons, as base editing occurs preferentially in these cells.
The study, while a significant step forward, acknowledges the complexity of ASD, which is associated with hundreds of mutations.
Chief physician Zou Xiaobing from Sun Yat-sen University emphasized that while the therapy is promising, especially for autism caused by single nucleotide variations like in the study, ASD often results from more complex mutations. He stressed the importance of personalized intervention and training based on each child’s specific situation.
The research presents a hopeful future for genetic brain disorder interventions, suggesting that in vivo base editing could be a feasible approach. However, it also acknowledges the current limitations in the scope of genetic editing targets and the need for broader targeting systems to facilitate the development of tools for intervening in genetic disorders.
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