Cascade of events leading to trisomy 12 dominance in iPSCs. The different steps (1–8) illustrate how replication stress at the tip of the 12p arm (due to its shorter telomere length) could trigger anaphase bridges and micronucleation of a single chromatid (steps 1–5). The reincorporation of chromosome 12 into the primary nucleus during the subsequent mitosis results in the formation of chromosome 12 trisomic cells (steps 6–8). As this process occurs simultaneously in many cells, and together with the mild proliferative advantage of trisomic cells, the population rapidly becomes near-complete trisomic.