Abstract 4135624: A Hypertrophic Cardiomyopathy Polygenic Score Modifies Penetrance of Pathogenic Hypertrophic and Dilated Cardiomyopathy Variants in Opposite Directions

Background: Hypertrophic (HCM) and dilated (DCM) cardiomyopathy have been postulated to represent morphologically opposing cardiac disease traits, with genetic pathways implicated in HCM demonstrating inverse relationships with DCM. The degree to which polygenic risk for HCM protects from DCM in individuals at genetic risk of DCM remains unexplored. Research Question: Is polygenic risk for HCM protective against developing DCM in carriers of titin truncating variants? Methods: Associations between polygenic risk for HCM, monogenic variants, and cardiomyopathy outcomes were modeled among Penn Medicine BioBank (PMBB) participants genetically similar to European reference populations using logistic regression. Polygenic risk for HCM was determined using a previously published HCM polygenic score (PGS; PGS Catalog PGS000739; Harper et al. 2021); scores were PCA adjusted, and the mean and variance were normalized using pgsc_calc. Pathogenic variants in definitive HCM genes were identified using ACMG criteria. Titin truncating variants in high percentage spliced in exons (TTNtv) were considered pathogenic. HCM and DCM outcomes were assigned based on diagnosis codes +/- clinical notes in the electronic health record. Results: Of 26,728 PMBB participants, 205 (0.77%) had HCM and 589 (2.2%) had DCM. 289 had a TTNtv, and 144 had a pathogenic HCM variant. Pathogenic HCM variant status (n=144) conferred a 76-fold increase in HCM risk (p=1.8 e-87). A one standard deviation change in HCM PGS had a significant positive association with HCM (OR 1.6; p=1.5e-9) and negative association with DCM (OR 0.72; p=1.e-12). TTNtv status (n=289) was associated with an increased risk of DCM (OR 5.0; p=1.4e-12). An interaction term between TTNtv status and HCM PGS had a negative association with DCM (OR 0.61; p=4.5e-2). Among the top HCM PGS quintile, there was no statistically significant difference in DCM risk between those with and without TTNtv (Figure 1). Conclusions: These results provide additional evidence that HCM and DCM are influenced by polygenic background. We observe that polygenic risk of HCM additively increases risk of HCM among pathogenic HCM variant carriers and may synergistically protect from DCM among TTNtv carriers.