568. Transient Manipulation of DNA Damage Repair Pathway Choice Improves Homology-Directed Repair During CRISPR/Cas9-Mediated Genome Editing
CRISPR/Cas9 system allows efficient gene ablation through error-prone non-homologous end joining DNA repair. However, very low efficiency of homology-directed DNA repair (HDR) is the bottleneck in correcting genetic mutations of clinical relevance. Here we report that transient manipulation of DNA damage repair pathways increases the HDR frequency by 3-5 fold. Furthermore, we show that this approach is applicable to introduce precise genetic modifications at many genetic loci in multiple cell-types including human induced pluripotent stem (hiPS) cells. Furthermore, unbiased off-target mutational analysis using High Throughput Genome-wide Translocation Sequencing (HTGTS) suggests that transient manipulation of DNA damage repair pathways have no adverse effect on either CRISPR/Cas9 specificity or genomic integrity. Our data suggests that this approach could be used for correcting various genetic disorders in relevant cell types.