TABLE 4.

Advantages and Disadvantages of Gene Editing Methods

Method	Advantages	Disadvantages
ZFNs	Short time-course (~ 6 months) High frequency of targeted gene disruption	Screening and assembly is technically challenging Requires extensive screening to detect target events High level of off-target effects Commercially available modules are expensive Difficult to perform large fragment (> 1 kb) replacement
TALENs	Unconstrained target site requirements High degree of specificity Low off-target effects Little evidence of mismatch tolerance	Sensitive to cytosine methylation, especially at CpG dinucleotides
CRISPRs	High target site specificity High frequency of gene targeting Ease of design and construction	gRNAs can tolerate up to five mismatches with unwanted target sites High level of indel formation at unintended sites High level of off-target effects