Overview
- A Nature paper published on 28 October 2026 analyzed more than 2,300 single neurons and found that over one-quarter of fetal cortical neurons carried large copy number variants, while about 6% remained after birth.
- The team used a new, lower-cost single-cell genome sequencing method for broad screening and validated key results with deeper sequencing to confirm the high prenatal prevalence of chromosomal gains and losses.
- Neurons that carried many copy number variants showed disrupted activity of genes that build and maintain synapses, which the authors link to a failure to win connections and subsequent elimination.
- The sharp decline in abnormal neurons around the time of birth supports a model of developmental culling that continues slowly through adulthood, leaving a small, persistent mosaic of variant-bearing cells.
- Beyond basic biology, the work opens research paths into whether this elimination process is altered in autism, epilepsy or schizophrenia and whether it affects later neurodegeneration, and it provides a scalable tool to map such links.