Rare genetic variants in LDLR, APOB, and PCSK9 are associated with aortic stenosis

Abstract Background Aortic stenosis (AS) is the most common cardiac valvular disease in the developed world. Although AS is associated with substantial morbidity and mortality, current treatment options are limited to invasive procedures and reserved for severe symptomatic disease. Genetic studies have linked common variants near lipid genes to AS and cohort studies have linked diagnoses of familial hypercholesterolemia to AS. In contrast, randomized controlled trials have shown no benefit of lipid-lowering therapy in AS. Purpose We aimed to assess the impact on AS conferred by lifelong decreased or increased LDL levels, by studying rare genetic variation in three important lipid handling genes (LDLR, APOB, PCSK9) from a genome-first perspective. Methods We utilized sequencing data and electronic health records from the UK Biobank (UKB) and the All of Us Research Program (AllofUs). We used LOFTEE to identify carriers of truncating variants in LDLR (LDLRtv), APOB (APOBtv) and PCSK9 (PCSK9tv); we used AlphaMissense to identify predicted-damaging missense variants (LDLR-AM, APOB-AM, PCSK9-AM). Linear regression analyses were used to assess the impact of the variant groupings on LDL levels in the UK Biobank, adjusting for sex, age, age^2, and principal components of ancestry. We then conducted Firth’s logistic regression analyses in UK Biobank and AllofUs modelling AS as outcome and variant status as predictor, adjusting for the same covariates; we used an inverse-variance-weighted meta-analysis to combine results. Results We identified 421,058 unrelated participants (N=5,322 AS cases) in the UK Biobank, and 232,170 unrelated participants (N=1,087 AS cases) in AllofUs. Across both cohorts, we identified 198 LDLRtv carriers, 1095 LDLR-AM carriers, 662 APOBtv carriers, 1422 APOB-AM carriers, 712 PCSK9tv carriers and 794 PCSK9-AM carriers. In the UK Biobank LDL values were substantially elevated in LDLRtv (P=1.9x10-48) and LDLR-AM carriers (P=7.5e-200), while LDL levels were substantially decreased in APOBtv (P<1x10-200), APOB-AM (P=6.3x10-19), PCSK9tv (P=1.2x10-114) and PCSK9-AM carriers (P=9.9x10-73; Figure 1). Across UK Biobank and AllofUs, the risk of being diagnosed with AS was strongly increased in LDLRtv (odds ratio [OR]=9.2 [4.32–19.50], P=8e-9) and LDLR-AM carriers (OR=2.76 [1.75–4.35], P=1e-5; Figure 2). Directionally consistent with these effects, we observed a trend towards decreased AS risk among carriers of either APOBtv or PCSK9tv (OR=0.57, [0.30–1.08], P=0.08) and a significantly reduced risk among carriers of APOB-AM or PCSK9-AM (OR=0.46, [0.26-0.82], P=0.009). Conclusion Rare genetic variants that confer lifelong increased LDL levels are associated with substantially increased risk of AS, and vice versa. Our results support a causal role of LDL in AS pathogenesis. In the context of trials demonstrating no benefit in AS, our findings suggest that lipid-lowering may need to be initiated earlier to affect AS development.LDL levels in UK BiobankAS risk in UK Biobank and AllofUs