Brain Development Research Offers Clues to Autism

Key takeaways

• Up to 46% of neurons in the developing brain carry multiple copy number variants (CNVs), which involve DNA segment deletions or duplications.
• The proportion of neurons with widespread CNVs fell from an average of 25.9% before birth to 6.2% after birth.
• Researchers suggest that competition to form and maintain synapses may help eliminate neurons with extensive genomic abnormalities.
• The findings could help researchers investigate autism, epilepsy, schizophrenia, and other neurodevelopmental conditions.
• For More Updates in Neurology, register for American Neurology Summit 2026 (ANS 2026)

Brain Development Reveals a Natural Quality-Control Mechanism

Brain development may rely on a natural quality-control process that removes neurons with extensive genetic abnormalities. Researchers from Harvard Medical School (HMS) and Boston Children’s Hospital have found that neurons carrying multiple copy number variants (CNVs) are common during prenatal development but become far less prevalent after birth.

Published in Nature on October 28, 2026, the study suggests that competition to establish synaptic connections may help eliminate neurons with genomic abnormalities. CNVs involve duplications or deletions of DNA segments and can affect genes involved in brain function. These alterations have links to neurodevelopmental conditions, including autism, epilepsy, schizophrenia, and intellectual disability.

The findings offer new insights into how the developing brain maintains genomic integrity while producing an excess of neurons. They may also help researchers investigate whether disruptions in this quality-control process contribute to neurological and neuropsychiatric disorders.

How Synaptic Competition Helps Remove Abnormal Neurons

To investigate CNVs across individual neurons, the research team developed a lower-cost method for sequencing single-cell genomes. Researchers applied the method to 1,526 neurons from 16 individuals and validated their findings through deeper sequencing of 831 neurons from 12 individuals.

The analysis revealed that an average of 25.9% of neurons in the prenatal cortex carried widespread CNVs, with some samples approaching 46%. After birth, this proportion dropped to an average of 6.2%. The researchers also found evidence that the brain continues to eliminate abnormal neurons during adulthood, although at a slower rate.

To investigate the underlying mechanism, the team analyzed DNA and RNA from 44,861 individual cells. Neurons with widespread CNVs showed abnormal expression of genes involved in creating and maintaining synapses, the connections through which neurons communicate.

Previous research has established that developing neurons compete to form these connections. Neurons that fail to establish adequate synaptic connections often die. The new findings suggest that neurons with extensive genomic abnormalities may struggle to compete successfully, contributing to their selective elimination.

However, the study identifies a potential mechanism rather than establishing every step of the process conclusively.

Implications for Autism and Neurodegenerative Disorders

The findings raise important questions about whether this neuronal quality-control mechanism operates differently in people with neurodevelopmental disorders. The researchers are investigating whether abnormal neuronal elimination contributes to autism and related conditions, where disrupted synaptic pruning has already attracted scientific interest.

The team is also examining whether similar processes contribute to neuronal loss in adult-onset neurodegenerative disorders, including Alzheimer’s disease.

Not all genomic variation disappears from the brain. Some neurons carrying genetic differences remain in healthy adults, and researchers do not yet know whether this variation serves a useful function or simply reflects normal development.

For More Updates in Neurology, register for American Neurology Summit 2026 (ANS 2026)

For neurologists, neuroscientists, and other healthcare professionals, the research provides a new framework for understanding neuronal survival, synaptic development, and genomic abnormalities. Further studies will need to clarify the underlying mechanisms and determine whether they offer clinically useful insights into neurological disorders.

Source:

Harvard Medical School