CRISPR: Established Editor of Human Embryos?

Off-target effects and mosaicism are major concerns for applying CRISPR-Cas9 to correct genetic mutations. A recent article in Nature by Ma et al. (2017) uses an elegant CRISPR-Cas9 approach that repairs a genetic mutation in human embryos with negligible mosaicism and no off-target effects, bringing this editing tool closer to clinical application.