Table 1.

Comparison of CRISPER/Cas9 with ZFN and TALEN.

Editing Technology	DNA Binding Determinant	Endonuclease	Target Length (bp)	Off Targeting	Intended Effects	Unintended Effects
CRISPR/Cas9	crRNA/sgRNA	Cas9	18–21	Variable	Highly specific, highly efficient, and multiple targeting sites	Target selection limited by the requirement for PAM sequences; Off-target effects
ZFN	Zinc finger protein, FokI1018	FokI	18–36	High	Any genomic sequence targeted; Fewer off-target effects	Low efficiency; Targets only a single site at one time
TALENs	Transcription-activator like effector	FokI	30–40	Low	Targets any genomic sequence; Off-target effects are limited	Comparatively low inefficiency; Targets only a single site at one time; Sensitive to target DNA methylation