Table 3 Comparison between the three main genome-editing tools
From: New insights on CRISPR/Cas9-based therapy for breast Cancer
| Â | ZFN | TALEN | CRISPR |
|---|---|---|---|
Nature | Engineered protein to target specific DNA sequences | Engineered protein to target specific DNA sequences | Short sequence of RNA that can target specific DNA sequences |
Target/sensitivity | Protein–DNA interaction, less sensitive | Protein–DNA interaction, less sensitive | RNA–DNA interactions, highly sensitive |
Size of recognized target | 18–36 nt | 30–40 nt | 22 nt |
Off targeting | High | Moderate | Low |
Efficiency | Moderate | Moderate | High |
Nuclease – D/M | FokI – dimer | FokI – dimer | Cas9 – monomer |
Mode of action | For ZFN to work, it requires two sets to hybridize each to each DNA strand around the target sequence | For TALEN to work, it requires two sets to hybridize each to each DNA strand around the target sequence | In the presence of gRNA, Cas9 can reach the target DNA sequence and generate double strand breaks. |
Cytotoxicity | Moderate | Low | Low |
Multiple targets | Difficult | Difficult | Doable |
Cost/benefits | High cost and time consuming | High cost and time consuming | Low cost and less time needed |