Gene knockout and knockin by zinc-finger nucleases: current status and perspectives

Zinc-finger nucleases (ZFNs) are engineered site-specific DNA cleavage enzymes that may be designed to recognize long target sites and thus cut DNA with high specificity. ZFNs mediate permanent and targeted genetic alteration via induction of a double-strand break at a specific genomic site. Compared to conventional homology-based gene targeting, ZFNs can increase the targeting rate by up to 100,000-fold; gene disruption via mutagenic DNA repair is similarly efficient. The utility of ZFNs has been shown in many organisms, including insects, amphibians, plants, nematodes, and several mammals, including humans. This broad range of tractable species renders ZFNs a useful tool for improving the understanding of complex physiological systems, to produce transgenic animals, cell lines, and plants, and to treat human disease.