Through early research in mice, Johns Hopkins and Academia Sinica researchers found a tailored therapy prevented brain damage and improved behavior in mice with a rare neurodevelopmental genetic mutation

Scientists at Johns Hopkins University School of Medicine and Academia Sinica in Taiwan have developed an experimental RNA-based treatment that prevents brain damage and improves learning, memory, and social behavior in mice carrying a rare genetic mutation associated with autism spectrum disorder and intellectual disability.

These findings, supported by the National Institutes of Health, published in Neuron on Nov. 11.

Through this research, the investigators showed how a mutation in GRIA1, a gene encoding a key component of AMPA receptors, disrupts brain development. These receptors control communication between neurons and are essential for learning and memory. The researchers also demonstrate that selectively silencing the mutant gene copy can prevent many of its harmful effects in mice, which provides a promising strategy for treating genetic disorders affecting neurotransmitter receptors.

“Our findings show how a single genetic mutation can disrupt brain development and lead to significant neurological impairments,” says Richard L. Huganir, Ph.D., professor of neuroscience at Johns Hopkins University School of Medicine and co-corresponding author of the study. “Importantly, we demonstrate that selectively targeting the mutant gene can prevent neuronal damage and improve behavioral function. This opens an exciting avenue for developing precision therapies for rare neurodevelopmental disorders.”

How a Single Mutation Disrupts Brain Development

The researchers studied a mutation called A636T in the GluA1 subunit of AMPA receptors, which has been identified in individuals with autism spectrum disorder and intellectual disability.

AMPA receptors are essential for communication between neurons and play a critical role in the formation and function of neural circuits. Normally, as the brain develops, these receptors undergo changes that limit the amount of calcium entering neurons. Although calcium is essential for neuronal communication, excessive calcium entry can damage or kill neurons.

The researchers discovered that the A636T mutation interferes with this protective developmental process, allowing excessive calcium to enter neurons. In genetically engineered mice carrying the mutation, this abnormal activity caused progressive damage to the hippocampus, a brain region critical for learning and memory.

Affected mice developed neuronal degeneration, inflammation, and significant impairments in learning, memory, and social behavior. They also exhibited increased anxiety-like and repetitive behaviors, resembling some features observed in human neurodevelopmental disorders.

These findings reveal how a single mutation in a neurotransmitter receptor can disrupt normal brain development and produce widespread neurological and behavioral abnormalities.

A Precision RNA Treatment Prevents Neuronal Damage

To counteract these effects, the researchers developed an antisense oligonucleotide (ASO), a short synthetic molecule designed to recognize and silence a specific RNA message.

Unlike conventional treatments that broadly suppress AMPA receptor activity, the ASO selectively targeted RNA produced by the mutant GRIA1 gene copy, reducing production of the abnormal receptor while preserving expression of the normal gene copy.

Remarkably, a single administration of the optimized ASO shortly after birth prevented hippocampal neuronal damage, restored more normal synaptic function, reduced neuroinflammation, and significantly improved learning, memory, and social behavior in the mutant mice.

These findings demonstrate that selectively suppressing a disease-causing mutation can protect developing brain circuits and prevent many of the neurological and behavioral abnormalities associated with the mutation.

Toward Precision Treatments for Rare Brain Disorders

The study provides important proof of principle for developing personalized RNA therapies for neurodevelopmental disorders caused by mutations in neurotransmitter receptors.

“Our study demonstrates that even severe developmental abnormalities caused by a mutant neurotransmitter receptor can be prevented by targeting the underlying genetic defect,” says Huganir. “This provides hope that precision RNA therapies could eventually benefit patients with these devastating disorders.”

ASO-based therapies have already been developed for neurological conditions such as spinal muscular atrophy and certain forms of Batten disease. Similar approaches are being investigated for other neurological disorders, including ALS, Huntington’s disease, and rare genetic epilepsies.

The investigators plan to continue studying the mechanisms underlying these disorders in mice and human stem cell models while further optimizing RNA-based therapies for potential clinical applications.

“This study highlights the potential of precision medicine to address the underlying genetic causes of neurodevelopmental disorders rather than simply treating their symptoms,” says Huganir.

Additional coauthors include Chih-Ming Chen, Yu-Min Huang, Chi-Ching Chung, Richard Johnson, Cheng-Ya Tsai, Yu-Han Chen, Han Tan, Fu-Yun Hsiao, and Shu-Ling Chiu.

The research was supported by grants from the National Institutes of Health (R37 NS036715), the National Science and Technology Council, Taiwan (110-2628-B-001-018, 111-2628-B-001-009, 112-2628-B-001-003, 113-2311-B-001-025, and 114-2320-B-001-020-MY3), and an Academia Sinica Career Development Award (AS-CDA-111-L02).

The authors report no competing interests.