PROJECT SUMMARY Heart diseases are the number one leading cause of death in the United States and worldwide, responsible for over 655,000 American deaths each year. The most prevalent cardiovascular diseases (CVD) such as coronary artery disease (CAD) arise from the interplay between complex genetic variants and environmental factors. In particular, the low-density lipoproteins (LDL) is critical contributing factor to atherosclerosis and increased risk of CVD. The use of statin drugs considerably reduced the incidence of CVD. Despite the enormous progress of clinical practice in the past 30 years, insufficient LDL-cholesterol reduction and relatively high residual risk remains for a significant proportion of statin-treated patients with or without combination therapy, likely due to persistent relatively high triglyceride (TG) levels. This underscores the need for additional new therapies targeting lipid metabolism in CVD prevention and treatment. Recent advances in genome editing technologies, in particular the base editors, empower us to explore the feasibility of precise correction of genetic mutations for genetic cardiomyopathy such as Duchenne muscular dystrophy (DMD). In a mouse model of DMD, we recently achieved a near complete dystrophin restoration in the heart after a systemic delivery of adenine base editor and the gRNA with adeno-associated virus 9 (AAV9). Leveraging this exciting advancement in the in vivo base editing technology, here we will develop more broadly applicable therapeutic strategies to combat CVD in a “hit-and-run” fashion (a technology we referred to as diBE), thus minimizing the potential risks associated with AAV-mediated persistent expression of base editing reagents, which are known to have intrinsic off-target DNA and RNA editing activities. We will determine the therapeutic potential of diBE- mediated silencing of Asgr1 for protection against high fat diet induced hypercholesterolemia and atherosclerosis in mice. Completion of these studies will have a high potential for making a major impact on the development of novel base editing therapies to treat hyperlipidemia and CVD.