High aneuploidy in fetal neurons

The study found that more than a quarter of neurons in fetal brain samples showed significant chromosomal abnormalities, such as gains or losses of genetic material. These abnormalities, known as aneuploidy, are common during early development and can affect up to 73 percent of embryos in some cells.

Lower aneuploidy after birth

After birth, the proportion of neurons with extensive chromosomal abnormalities dropped by about 4.5 times. In postnatal samples, only about 6 percent of neurons showed such significant genomic alterations, suggesting a possible "quality control" mechanism that favors the survival of neurons with fewer genetic changes.

Aneuploidy and brain function

Chromosomal variations can disrupt the function of genes involved in brain processes like synapse formation, which is crucial for neuron communication. This disruption may explain why neurons with more genetic abnormalities are selectively eliminated during development.

Possible link to neurodevelopmental disorders

Some studies have linked chromosomal copy number variations to neurodevelopmental and psychiatric conditions such as autism and schizophrenia. A breakdown in the brain's quality control system, which eliminates abnormal neurons, could contribute to these disorders, though this remains a hypothesis that needs further research.

New insights from recent research

A study published in the journal Nature on October 28 analyzed cerebral cortex samples from human donors across different life stages, from fetal development to old age. Researchers used advanced sequencing techniques to examine individual neuron genomes and found extremely high aneuploidy rates in fetal brains.

Selective elimination of neurons

The study suggests that neurons with the most intact genomes are more likely to survive, possibly due to disruptions in synaptic activity in neurons with more genetic variations. This selective elimination may be a key factor in shaping the adult brain, though the exact mechanisms are still unclear.