“…CRISPR/Cas9 genome modification is a powerful approach for generating both targeted indel mutations by non-homologous endjoining (NHEJ) repair and more precise gene editing by the introduction of specific sequences through homology-directed repair (HDR) (Auer et al, 2014;Bassett et al, 2014;Bhattacharya et al, 2015;Blitz et al, 2013;Chen et al, 2013;Friedland et al, 2013;Guo et al, 2014;Hisano et al, 2015;Kimura et al, 2014;Kotani et al, 2015;Li et al, 2015;Nakayama et al, 2013Nakayama et al, , 2014Ran et al, 2013;Shi et al, 2015;Wang et al, 2015;Yang et al, 2014). While NHEJ-mediated indel mutations have proven to be effective in animal models including mouse, zebrafish and Xenopus (Blitz et al, 2013;Kotani et al, 2015;Nakayama et al, 2013;Wang et al, 2015;Xue et al, 2014), HDR-mediated targeted DNA insertion has proven more challenging.…”