From: Towards a new era in medicine: therapeutic genome editing
Nuclease | Target site length | Mechanism of recognition | First use in human cells | Ease of design | Number of components | Size of mRNA transcript |
---|---|---|---|---|---|---|
Engineered meganuclease | >18Â bp | Protein-DNA | 1994 (I-SceI) | Extremely difficult | 1 | Short |
Zinc-finger nuclease | 18–36 bp | Protein-DNA | 2003 | Difficult | 2 | Short |
TAL effector nuclease | 24–40 bp | Protein-DNA | 2011 | Easy | 2 | Long |
CRISPR/Cas9 nuclease | 19–22 bp (Streptococcus pyogenes Cas9) | RNA-DNA Watson-Crick base-pairing | 2013 | Simple | 1 (if using a complex guide RNA with Cas9 protein) or | Long |
2 (if delivering guide RNA and Cas9 separately) |