Background and purpose

Lacunar stroke (LS) and intracerebral hemorrhage (ICH) are 2 diverse manifestations of small vessel disease. What predisposes some patients to ischemic stroke and others to hemorrhage is not well understood.

Methods

We performed a nested case-control study within the FHS (Framingham Heart Study) comparing people with incident ICH and lacunar ischemic stroke, to age- and sex-matched controls for baseline prevalence and levels of cardiovascular risk factors.

Results

We identified 118 LS (mean age 74 years, 51% male) and 108 ICH (75 years, 46% male) events. Hypertension, diabetes mellitus, smoking, and obesity were strongly associated with LS. Hypertension, but not diabetes mellitus, smoking, or cholesterol levels increased the odds of ICH. Contrary to LS, ICH cases had lower body mass index (BMI) than their controls (26 versus 27); BMI <20 was associated with 4-fold higher odds for ICH. In direct comparison, LS cases had higher BMI (28 versus 26) and obesity prevalence (odds ratio, 3.1); BMI <20 was associated with significantly lower odds of LS (odds ratio, 0.1).

Conclusions

LS and ICH share hypertension, but not diabetes mellitus, as a common risk factor. ICH cases had lower BMI compared with not only LS but their controls as well; this finding is unexplained and merits further exploration.

Background

Multi-phenotype analysis of genetically correlated phenotypes can increase the statistical power to detect loci associated with multiple traits, leading to the discovery of novel loci. This is the first study to date to comprehensively analyze the shared genetic effects within different hemostatic traits, and between these and their associated disease outcomes.

Objectives

To discover novel genetic associations by combining summary data of correlated hemostatic traits and disease events.

Methods

Summary statistics from genome wide-association studies (GWAS) from seven hemostatic traits (factor VII [FVII], factor VIII [FVIII], von Willebrand factor [VWF] factor XI [FXI], fibrinogen, tissue plasminogen activator [tPA], plasminogen activator inhibitor 1 [PAI-1]) and three major cardiovascular (CV) events (venous thromboembolism [VTE], coronary artery disease [CAD], ischemic stroke [IS]), were combined in 27 multi-trait combinations using metaUSAT. Genetic correlations between phenotypes were calculated using Linkage Disequilibrium Score Regression (LDSC). Newly associated loci were investigated for colocalization. We considered a significance threshold of 1.85 × 10^-9 obtained after applying Bonferroni correction for the number of multi-trait combinations performed (n = 27).

Results

Across the 27 multi-trait analyses, we found 4 novel pleiotropic loci (XXYLT1, KNG1, SUGP1/MAU2, TBL2/MLXIPL) that were not significant in the original individual datasets, were not described in previous GWAS for the individual traits, and that presented a common associated variant between the studied phenotypes.

Conclusions

The discovery of four novel loci contributes to the understanding of the relationship between hemostasis and CV events and elucidate common genetic factors between these traits.