|
| Cre/LoxP | Flp/Frt | ZFN | TALEN | CRISPR/Cas9 |
| Design and assembly | Easy | Easy | Difficult | Difficult | Easy |
| Targeting site | 34 bp | 34 bp | 9 - 18 bp for ZFN monomer, 18-36 bp for ZFN dimer | 14 - 20 bp for TALEN dimer, 28 - 40 bp for TALEN dimer | 23 bp including 20 bp binding site and 3 bp PAM, multiple editing simultaneously |
| Restriction for target sites on genome | High | High | No | No | Low |
| Mismatch tolerance at target site | No | No | Low | Low | Relatively high |
| Targeting efficiency | Low | Low | Low | Moderate | High |
| Repair mechanism | HR | HR | NHEJ and HR | NHEJ and HR | NHEJ and HR |
| Off-target effects | Not available | Not available | Low | Low | Low |
| Transgene-free in offspring | No | No | Yes | Yes | Yes |