Gene editing holds great therapeutic promise for the treatment of several disorders, including inherited genetic diseases, infections and cancer. Molecular editors (e.g., CRISPR/Cas nucleases, base/prime editors) enable site-specific modification of the human genome. Overall, these tools are mainly exploited to achieve: i) gene knock-out by disruption of coding or regulatory sequences; ii) precise correction of disease-causing point mutations; iii) targeted integration of therapeutic cassettes. Several clinical trials are on-going, or foreseeable in the near future, to evaluate safety and efficacy of these cutting-edge platforms before widespread implementation.

Remarkable efforts are being pursued to develop reagents and procedures that maximize editing efficiency, while preserving cellular function and minimizing undesired off-target events. To this goal, optimized viral and non-viral vectors (e.g., AAV, electroporation, lipid nanoparticles, etc…) can be used to efficiently deliver editing components to the target cell type(s) depending on the specific application. Moreover, the molecular editors are continuously evolved to enhance their activity and specificity, which can be carefully evaluated by several in-silico, in-vitro and in-cellulo assays. Finally, transient and reversible manipulation of cellular pathways (e.g., inhibition of non-homologous end joining, stimulation of homologous recombination) can sometimes be proposed as complementary approaches to force the intended edit or improve tolerability of genetic manipulation.

The aim of this collection is to highlight methodologies assessing and/or improving efficiency, precision, and tolerability of therapeutic gene editing. These could include editing protocols expanding scope and means of therapeutic gene editing, as well as computational or molecular technologies predicting or quantifying on-/off-target editing activity.