The researchers created a single-cell atlas of the cerebral cortex of fetuses with Down syndrome using single-cell RNA and ATAC sequencing. The study maps the development of the cerebral cortex and reveals regulators on chromosome 21 that influence networks of genes associated with intellectual disability. The analyzes used specific pipelines for processing data from a single-cell atlas of the fetal cerebral cortex with Down syndrome. The atlas captures cell types and their dynamics during development. Major findings identify key genes on chromosome 21 as regulators of intellectual disability. The data is available on the GitHub repository for further analysis. The study was published in Nature Medicine on January 16, 2026.