ABSTRACT – Resource Core II: In Vivo Core The proposed U19, referred to as the CASEPR program, aims to develop robust, durable disease-modifying CRISPR-mediated genomic gene-editing therapies for the neurodegenerative disorders of Huntington’s disease (HD) and C9orf72-associated amyotrophic lateral sclerosis (C9-ALS). These investigations will require preclinical in vivo studies of drug delivery and efficacy. The mission of ‘Resource Core II: In Vivo Core’ is to carry out all of the in vivo non-GLP small animal studies for the research programs supported by this U19. The In Vivo Core will provide essential services necessary to carry out all three research projects in the CASEPR program through the following aims: In Aim 1 the In Vivo Resource Core will perform all of the non-GLP in vivo administration of gene-editing vectors for all CASPER program research projects to achieve optimal dosing and distribution of the CRISPR vectors using convection-enhanced delivery neurosurgical techniques. In Aim 2 we will conduct standardized phenotypic assays in mouse models of disease to assess the efficacy of gene editing on rescue of disease-related behavior. Finally, in Aim 3 In Vivo Core researchers will be responsible for procuring relevant tissues from experimental animals and shipping of materials to the other resource cores, the Genomics Core and the Biological Outcomes Core, as appropriate. Centralizing the in vivo non-GLP small animal work will ensure uniformity in both neurosurgical studies and behavioral assessments across all projects. Research output from the In Vivo Core will provide essential data on investigational drug targeting, distribution, editing efficacy, and behavioral impact. The services provided by the In Vivo Core will accelerate the timeline from preclinical animal studies to IND by consolidation of resources and expertise.