The hidden risks of CRISPR/Cas: structural variations and genome integrity.

CRISPR/Cas technology has revolutionized genome engineering, unlocking unprecedented therapeutic potential. However, beyond well-documented concerns of off-target (OT) mutagenesis, recent studies reveal a more pressing challenge: large structural variations (SVs), including chromosomal translocations and megabase-scale deletions, particularly in cells treated with DNA-PKcs inhibitors. These undervalued genomic alterations raise substantial safety concerns for clinical translation. As more CRISPR-based therapies progress toward the clinic, understanding and mitigating these risks is paramount. Here, we review emerging evidence on on-target aberrations and chromosomal translocations, identify key gaps in our understanding of the DNA repair pathways underlying these adverse effects, and discuss strategies to improve the safety of genome editing.