Table 2.

Characteristics of different gene editing tools (Adapted from Chen and Gao 2014).

Characteristic	ZFN	TALEN	CRISPR/Cas9
Binding principle	Protein-DNA	Protein-DNA	RNA-DNA
Ease of design	Moderate	Easy	Very Easy
Assembling	Difficult	Easy	Very Easy
Time for construction	5–7 days	5–7 days	1–3 days
Cost	High	Moderate	Low
Efficiency	Variable	High	High
Off-target effects	High but variable	Low	High
Single-unit or pair	Pair	Pair	Single-unit