The brain liquidates billions of mutant neurons around the time we’re born

Key Points:

• A study analyzing over 2,300 neurons found that more than 25% of fetal brain neurons had chromosomal segment gains or losses, while only about 6% of neurons in newborns showed such abnormalities, indicating a significant reduction around birth.
• This reduction suggests a natural quality control mechanism where neurons with more intact genomes are selectively preserved during brain development.
• The research highlights a potential regulatory process determining neuron survival, which may be crucial for understanding childhood neurological disorders like autism spectrum disorder and epilepsy.
• The study focused on the cerebral cortex and found that neurons with high copy number variation also exhibited abnormal gene activity related to synapse formation, possibly marking them for elimination.
• These findings provide new insights into brain development and the genetic mosaicism present within individuals, challenging previous assumptions about neuronal genome stability.