About the cover
The development of the CRISPRCas9 gene-editing tool has revolutionized molecular biology. Used to modify the genomes of viruses, bacteria, animals and plants, it has the potential to reveal the secrets of genomic organization, combat disease, improve crops, make designer pets and much more. All this complicated by the announcement that the technique has been used to modify the genomes of human embryos presents formidable ethical problems for regulatory bodies to wrestle with. This special issue of Nature surveys the CRISPRCas9 scene and poses the question: what do we want a gene-edited world to look like? Cover art by Chris Labrooy.