Background: Peripheral Artery Disease (PAD) is a major source of cardiovascular morbidity and mortality, affecting >230 million individuals worldwide. While PAD may initially cause exertional limb pain (claudication), progression leads to chronic limb threatening ischemia (CLTI; rest pain and/or tissue loss) and amputation, which are associated with high rates of hospitalization and death. Genetic variants associated with PAD susceptibility have been identified using genome-wide association studies (GWAS). However, the role of genetic variation in the progression of PAD and disease severity remains poorly understood. Methods: GWAS of progression to CLTI were performed among individuals with PAD in the VA Million Veteran Program (MVP) and Copenhagen Hospital Biobank (CHB), accounting for age, sex, and genetic principal components. GWAS were first performed among genetically inferred ancestry subpopulations (EUR: European; AFR: African; AMR: admixed American), and combined using fixed-effects meta-analysis. SlopeHunter was used to account for index-event bias using a GWAS of prevalent PAD. Genetic associations with PAD severity (claudication, CLTI, amputation) were evaluated using multinomial logistic regression. Results: Up to 21.1 million genetic variants were tested for association with CLTI (17,641 individuals) in comparison to PAD (75,133 individuals). A total of 3 genetic loci were associated with progression to CLTI (p < 5x10 -8 ). The strongest association with CLTI was rs6025 (OR 1.25, 95% CI 1.18 to 1.34, p = 4.62x10 -12 ), a common missense variant (p.Arg534Gln) encoding Factor V Leiden, with consistent effects accounting for index-event bias. Compared to 489,538 individuals without PAD in MVP, rs6025 was associated with increased risk of non-specific PAD (OR 1.15, 95% CI 1.1 to 1.2, p = 5x10 -8 ), claudication (OR 1.14, 95% CI 1.1 to 1.2, p = 1x10 -4 ), CLTI (OR 1.42, 95% CI 1.3 to 1.6, p = 7x10 -23 ), and amputation (OR 1.54, 95% CI 1.4 to 1.8, p = 2x10 -10 ). Conclusion: Our results implicate F5 p.Arg534Gln as a risk factor for PAD progression and severe PAD manifestations including CLTI and amputation. This result provides genetic support for a potential role of anticoagulation as a treatment to prevent PAD progression and severe outcomes.
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