 In this study, researchers used a new technique called clustered regularly interspaced short palindromic repeats, CISPR, associated, CAS, systems to induce targeted mutations in Medaka fish embryos. They found that the technique was highly effective and could be used to target any sequence adjacent to a specific nucleotide sequence known as a protospacer adjacent motif, PAM. Additionally, they discovered that reducing the dose of the SGRNA, single guide RNA, molecule could reduce the number of off-target mutations. This article was authored by Satoshi Ansai and Masato Kenoshita.