Table 1 Comparison of CRISPR/Cas9, ZFNs, TALENs, meganucleases and RNAi
From: CRISPR/Cas9: the Jedi against the dark empire of diseases
| Â | CRISPR/Cas9 | ZFNs | TALENs | Meganucleases | RNAi |
|---|---|---|---|---|---|
Target site | 19–22 bp | 18–36 bp | 24–40 bp | 14–40 bp | Target site should be located 50–100 nt from ATG |
Retargeting possibility | Easily retargeted without any complexity | Yes, but requires complex molecular cloning | Yes, but requires protein engineering | Yes, by protein engineering | Yes |
Nuclease | Cas9 | FokI | FokI | I-SceI | Dicer and Argonaute proteins |
Recognition mechanism | RNA-DNA | Protein-DNA | Protein-DNA | Protein-DNA | RNA |
Targeting restrictions | Protospacer adjacent motif (PAM) must be present | Non-G-rich sequences are difficult to target | T in the start and A at the end | Novel sequences are difficult to target | Only targets mRNA |
Efficiency | High | High | High | High | High |
Limitations | Off targets | Both expensive and time consuming to construct | Takes long to construct | Limited versatility in targeting | Off targets |
Cytotoxicity | Low | Low | Variable to high | Low | Variable to high |
Multiplexing ease | High | Low | Low | Low | High |
Cost | Low | High | Moderate | Low | Low |