Supplemental Proposal Evaluation of nonviral gene editing systems in the brain assisted by focused ultrasound Abstract Efficient nonviral gene editing of the brain may help tackle some of the intractable neuronal degenerative disorders. Compared with viral gene editing, it is more translatable since it should have more manageable toxicity and immunogenicity. Many gene editing applications may require multiple administrations if there is a high turnover of the tissue. Viral gene editing systems would be unsuitable because of concerns of immunogenicity. The major barrier to nonviral gene editing of the brain is the BBB. We previously pioneered the use of focused ultrasound (FUS) technology to achieve noninvasive, brain-specific delivery of therapeutic payloads including small molecules, proteins and adeno-associated virus (AAV). This Supplemental proposal aims to compare the nonviral gene editing systems developed by other SCGE teams. It is expected that these nonviral gene editing systems have shown promising editing efficiency in tissues other than the brain. The FUS delivery will be performed at Columbia on Ai9 mice and the brain tissues sent to JAX for independent gene editing analysis. The final experimental design will be established in consultation with the PIs. This unbiased comparative study will define the possibilities and limitations of nonviral brain gene editing in the brain assisted by FUS.