Table 1.

Comparison of TALEN and CRISPR-Cas9 systems

TALEN
Advantages	Disadvantages
~30 bp target requirement results in less off-target effects	Difficult protein engineering potentially increases time and financial investment
No PAM requirement; can target any sequence	Efficiency varies for each construct
	Cannot target methylated DNA
	Difficult to engineer nickase
CRISPR-Cas9
Advantages	Disadvantages
Able to multiplex	Higher potential for off-target effects
Easy to engineer	PAM requirement limits target
Can target methylated DNA
Easy to create a nickase