Applying CRISPR–Cas9 genome editing technologies in safe and reliable ways requires a firm appreciation of the specificity of target-site recognition and cleavage. In this Review the authors discuss various approaches for characterizing off-target effects of CRISPR–Cas9 genome editing, how mechanistic knowledge can drive the engineering of more-specific nucleases, and the implications for research and therapeutic applications.
- Shengdar Q. Tsai
- J. Keith Joung