PROJECT SUMMARY GENE EDITING CORE The Liu laboratory at the Broad Institute of MIT and Harvard will serve as the Gene Editing Core for the Program. Developing customized editing strategies that maximize therapeutic editing while minimizing undesired byproducts is important for the success of all Research Projects. A centralized Gene Editing Core staffed by Liu laboratory members will enhance the Program's efficiency by preventing bottlenecks in gene editing analyses and ensuring consistency in methods and materials used in the proposed projects. The Gene Editing Core has three central aims: 1) to assess on-target editing activity across all Research Projects from isolated cell lines and from animal tissue samples; 2) to assess off-target editing activity in treated cells; 3) to optimize gene editing technologies for therapeutic targets. The Core will play an essential role in generating rigorous analyses of gene editing outcomes for the IND submission of our trailblazer project, coordinating closely with the Preclinical Mouse Model Core analyze samples from large-scale efficacy studies. Additionally, the Core will facilitate the maturation of the Follower Projects by continuing to develop the latest base editing and/or prime editing technologies in model systems representative of each Follower Project's therapeutic target. Synergy between the Core and the Follower Projects will enable the co-development of new genome editing tools that maximize on-target editing efficiencies, minimize undesirable gene editing byproducts and off-target editing events, and maximize compatibility with in vivo delivery methods of potential therapeutic relevance.