Yin, H. et al. Nat. Biotechnol. doi:10.1038/nbt.2884 (30 March 2014).

The clustered, regularly interspaced, short palindromic repeats (CRISPR)-Cas9 system has been used for genome modification in many organisms, including for correction of disease-causing mutations in mouse zygotes. Yin et al. now report the use of CRISPR-Cas9 for mutation correction in the liver of adult mice that carry a point mutation in the gene encoding fumarylacetoacetate hydrolase (Fah), which causes acute liver damage and death. Delivery of a vector encoding a guide RNA targeting Fah and the Cas9 endonuclease, together with a single-stranded oligonucleotide carrying the desired mutation reversal, all to the liver, resulted in rescue of the animals as well as detectable Fah activity and gene correction. Methods remain to be developed for delivery and gene correction in other adult tissues.