Overview
- The Nature paper published Oct. 28, 2026, reports that about 25.9% of sampled prenatal cortical neurons carried widespread copy number variants while roughly 6.2% of postnatal neurons did, indicating a sharp perinatal drop in abnormal cells.
- Researchers analyzed single neurons from fetuses through nonagenarians using a new low-cost 'light' single-cell genome sequencing method validated by deeper sequencing and joint DNA/RNA profiling of about 44,861 cells.
- Neurons with many copy number variants showed abnormal expression of genes required for making and maintaining synapses, which the authors say explains how these cells fail to form connections and are outcompeted during development.
- The team found that the most abnormal neurons are largely removed around birth and that elimination continues into adulthood at a slower rate, leaving healthy adults with some persistent genomic mosaicism.
- Follow-up work enabled by the scalable methods will test whether disruption of this synaptic quality-control process contributes to conditions such as autism, epilepsy, or Alzheimer’s disease and will map where damaging variants occur in the genome.