The moving finger

Abstract

DNA-cleaving enzymes trigger a repair process that can now be harnessed to correct mutations in the human genome in vitro. This represents another step towards gene-correction strategies for treating human disease. A discovery reported in this issue could dramatically change the field of gene therapy. The current approach is to try to compensate for defective genes by inserting a new working copy into cells. This new work solves a long-standing problem that has prevented the efficient editing of the human genome, so that gene correction becomes a viable option. Editing of the human genome in vivo is hindered by the low frequency of homologous recombination. This was circumvented using specially engineered ‘zinc-finger’ nucleases as molecular scissors to cut DNA inside cells at a specific sequence. The DNA break is then patched using new genetic information. The efficiency of this process combined with the ability to design zinc-finger nucleases that target almost any DNA sequence mean that genome editing in human cells is likely to become an important research tool and potentially a powerful way of treating disease.