Abstract 16685: Shared Genetic Pathways Contribute to Risk of Hypertrophic and Dilated Cardiomyopathies With Opposite Directions of Effect

Abstract

Introduction: Hypertrophic (HCM) and dilated (DCM) cardiomyopathies are leading causes of sudden death and heart failure requiring transplantation in young individuals. While some cases have a monogenic underlying cause, the majority remain unexplained. Objective: To better understand the contribution of common genetic variants in susceptibility and severity of cardiomyopathy. Methods: We conducted three genome-wide association studies (GWAS) and multi-trait analyses in European-ancestry individuals, including a HCM (1,733 cases) and DCM meta-analyses (5,521 cases), and a GWAS of 9 left ventricular (LV) traits in 19,260 healthy participants from the UK Biobank that underwent cardiac magnetic resonance imaging. We investigated genetic correlations between LV traits, HCM and DCM using LD score regression. We used two-sample mendelian randomization (MR) to assess the causal relationship of increased LV contractility with HCM risk. Lastly, we derived a polygenic risk score and assessed whether it modulates maximal LV wall thickness (maxLVWT) and clinical events in 368 sarcomeric mutation carriers, using linear and Cox mixed effects models, respectively. Results: We identified 16 genetic loci (15 novel) associated with HCM, 13 loci (7 novel) associated with DCM, and 23 loci associated with LV traits. We showed strong genetic correlations between LV volumes and contractility traits in the general population and cardiomyopathies, with opposing effects in HCM and DCM. Using MR, we demonstrated a causal association linking increased LV contractility with HCM risk and estimated that each unit (1%) increase in LV ejection fraction increases the risk of HCM by 37% (95% CI 10%-69%, P=0.004). Lastly, a polygenic risk score (PRS HCM ) derived from the HCM GWAS was associated with maxLVWT (P=0.0001) and clinical events (P=0.009) in carriers of HCM-causing rare variants. Conclusion: Our findings highlight the contribution of common genetic variants in susceptibility for HCM and DCM, and in severity in sarcomeric mutation carriers. Our data also point to increased LV contractility as an important mechanism of HCM independently of sarcomere activating rare variants, and highlight the potential clinical relevance of PRS for risk stratification in HCM.