Genome engineering in human cells is of great value in research, medicine, and biotechnology. In research, one of the best ways to determine the function of a human gene or genetic element is to compare the phenotype of human cells containing a mutation in the gene or element of interest with that of isogenic normal human cells. This process is increasingly important given that a growing number of researchers are using human pluripotent stem cells as disease models to investigate disease pathophysiology and screen therapeutic drugs in vitro (Colman & Dreesen, 2009; Saha & Jaenisch, 2009). Furthermore, if reporter genes or peptide tags are inserted into endogenous genes through genome engineering, it becomes possible to monitor or trace those genes. In medicine, many genetic diseases could be prevented or treated if the genetic mutations that cause the disease were corrected, as has been done in cell or animal models (Li et al., 2011; Osborn et al., 2013; Schwank et al., 2013; Voit, Hendel, Pruett-Miller, & Porteus, 2014; Yin et al., 2014). This targeted genetic modification can potentially also be used to treat nongenetic diseases such as human immunodeficiency virus (HIV) infection, which has been tested in human patients (Holt et al., 2010; Tebas et al., 2014).