Gene editing based on the delivery of programmable nucleases and exogenous DNA molecules permits introducing short and large genetic changes at specific sites within the vast genomes of human cells. Often, however, the precision of gene editing is hampered due to off-target activities and, more pervasively, on-target effects derived from the repair of double-strand DNA breaks (DSBs) by non-homologous recombination processes. Single-strand DNA breaks (SSBs) made by sequence- and strand-specific nucleases (nickases) are intrinsically less disruptive than DSBs as, typically, SSBs are not engaged by these illegitimate recombination processes. I will cover work being carried out in our laboratory on the investigation of programmable nickases, in particular those based on the prototypic CRISPR-Cas9 system, for attaining heightened chromosomal DNA editing accuracy, including at sites recurrent in the genome and associated with essentiality. In addition, our research on converting adenoviral vectors into delivery agents of gene-editing tools, will be equally discussed.
