The authors felt they should cite the following article by Ohashi M, et al. (2015), which is included below as Reference 1. Specifically, in the Introduction the sentence, “Recently, Li et al. have achieved high efficiency (8–76%) of genome editing by using an episomal vector to express Cas9 and gRNA23.” should read: “Recently, two groups have achieved high efficiency of genome editing by using an episomal vector to express Cas9 and gRNA in both human somatic cells and mouse iPSCs23, 1.” In addition, in the Discussion, the sentence: “When we were preparing the manuscript, another group reported that the episomal CRISPR/Cas9 system could work efficiently in HeLa cells and mouse iPSCs23.” should read: “Two groups have reported that the episomal CRISPR/Cas9 system could work efficiently in both human somatic cells and mouse iPSCs23, 1.” © 2018, The Author(s).