CRISPR-Cas9-mediated ON-target genotoxicity – CRISPR-genotox

CRISPR-Cas9 nuclease is a very promising technology for gene therapy. The first clinical trials have started. However, genome editing, to be safe, must be precise and reliable. Genotoxicity at the targeted locus (ON-target) is little studied. Unexpectedly, we observed megabase-scale terminal chromosomal deletions, following the use of Cas9 nuclease to edit the genome at the UROS (Chr10) and the globin (Chr11) loci in cell lines. These results raise a potential new worrisome safety issue for CRISPR use in clinic. Indeed, theses undesired outcomes can lead to the loss of many genes. This nuclease side-effect was recently confirmed in human embryos. Its prevalence is unknown in human non-embryonic primary cells. This project will evaluate whether Cas9-mediated large genome modifications occur in primary cells currently involved in CRISPR-Cas9 gene therapies, measure their functional impact, and reveal the molecular mechanism(s) to find solutions to secure CRISPR-Cas9 technology.