Abstract: CRISPR/Cas9 gene-editing system has been broadly used in various fields of bioscience and medicine in recent years. It can be guided by RNA to specific DNA site thus achieving targeted gene editing. Off-target effect and editing efficiency remain two crucial issues facing the system. Currently, a number of researches have been focused on the optimization of the system by reducing off-target effects and increasing editing efficiency, which will help enhance its safety and expand its application.

Key words: CRISPR/Cas9, gene editing, off-target effect, editing efficiency