Associations of activated coagulation factor VII and factor VIIa-antithrombin levels with genome-wide polymorphisms...

Essentials A fraction of coagulation factor VII circulates in blood as an activated protease (FVIIa). We evaluated FVIIa and FVIIa-antithrombin (FVIIa-AT) levels in the Cardiovascular Health Study. Polymorphisms in the F7 and PROCR loci were associated with FVIIa and FVIIa-AT levels. FVIIa may be an ischemic stroke risk factor in older adults and FVIIa-AT may assess mortality risk.

Background A fraction of coagulation factor (F) VII circulates as an active protease (FVIIa). FVIIa also circulates as an inactivated complex with antithrombin (FVIIa-AT). Objective Evaluate associations of FVIIa and FVIIa-AT with genome-wide single nucleotide polymorphisms (SNPs) and incident coronary heart disease, ischemic stroke and mortality. Patients/Methods We measured FVIIa and FVIIa-AT in 3486 Cardiovascular Health Study (CHS) participants. We performed a genome-wide association scan for FVIIa and FVIIa-AT in European-Americans (n = 2410) and examined associations of FVII phenotypes with incident cardiovascular disease. Results In European-Americans, the most significant SNP for FVIIa and FVIIa-AT was rs1755685 in the F7 promoter region on chromosome 13 (FVIIa, β = -25.9 mU mL^-1 per minor allele; FVIIa-AT, β = -26.6 pm per minor allele). Phenotypes were also associated with rs867186 located in PROCR on chromosome 20 (FVIIa, β = 7.8 mU mL^-1 per minor allele; FVIIa-AT, β = 9.9 per minor allele). Adjusted for risk factors, a one standard deviation higher FVIIa was associated with increased risk of ischemic stroke (hazard ratio [HR], 1.12; 95% confidence interval [CI], 1.01, 1.23). Higher FVIIa-AT was associated with mortality from all causes (HR, 1.08; 95% CI, 1.03, 1.12). Among European-American CHS participants the rs1755685 minor allele was associated with lower ischemic stroke (HR, 0.69; 95% CI, 0.54, 0.88), but this association was not replicated in a larger multi-cohort analysis. Conclusions The results support the importance of the F7 and PROCR loci in variation in circulating FVIIa and FVIIa-AT. The findings suggest FVIIa is a risk factor for ischemic stroke in older adults, whereas higher FVIIa-AT may reflect mortality risk.