No off-target mutations in functional genome regions of a CRISPR/Cas9-generated monkey model of muscular dystrophy

CRISPR/Cas9 is now widely used in biomedical research and has great potential for clinical applications. However, the safety and efficacy of this gene-editing technique are significant issues. Recent reports on mouse models and human cells have raised concerns that off-target mutations could hamper applying the CRISPR technology in patients. The high similarities of nonhuman primates to humans in genome content and organization, genetic diversity, physiology, and cognitive abilities have made these animals ideal experimental models for understanding human diseases and developing therapeutics. Off-target mutations of CRISPR/Cas9 have been analyzed in previous studies of nonhuman primates, but no report has investigated genome-wide off-target effects in living monkeys. Here, we used rhesus monkeys in which a genetic disorder mimicking Duchenne muscular dystrophy had previously been produced with CRISPR/Cas9. Using whole-genome sequencing to comprehensively assess on- and off-target mutations in these animals, we found that CRISPR/Cas9-based gene editing is active on the expected genomic sites without producing off-target modifications in other functional regions of the genome. These findings suggest that the CRISPR/Cas9 technique could be relatively safe and effective in modeling genetic disease in nonhuman primates and in future therapeutic research of human diseases.