Complete chromosome 21 centromere sequencing in families with Down syndrome reveals centromere size asymmetry patterns

Researchers sequenced chromosome 21 centromeres from eight families with Down syndrome (trisomy 21) resulting from maternal meiosis I errors and compared them to 287 controls. Contrary to earlier hypotheses, small centromeres were not enriched in Down syndrome cases, though extreme centromere size asymmetry (>10-fold difference) was identified in two families with affected mothers carrying some of the smallest observed centromeres.