Common hemostasis and inflammation gene variants and venous thrombosis in older adults from the Cardiovascular Health Study

Dysfibrinogenemia-Potential Impact of Genotype on Thrombosis or Bleeding

The congenital dysfibrinogenemias, most often associated with bleeding disorders, encompass mutations in the amino-terminal end of fibrinogen α-chain consisting of Gly17-Pro18-Arg19-Val20, known as knob A, which is a critical site for fibrin polymerization. Here we review the studies reporting dysfibrinogenemia due to mutations affecting fibrinogen knob A and identified 29 papers. The number of reports on dysfibrinogenemias related to residues Gly17, Pro18, Arg19, and Val20 is 5, 4, 18, and 2, respectively. Dysfibrinogenemias related to residues Gly17, Pro18, and Val20 are exclusively associated with bleeding tendency. However, the clinical picture associated with dysfibrinogenemia related to residue Arg19 varies, with most patients suffering from bleeding tendencies, but also transitory ischemic attacks and retinal thrombosis may occur. The reason for this variation is unclear. To elaborate the genotype-phenotype associations further, we studied a Danish family with knob A-related dysfibrinogenemia caused by the Aα Arg19Gly (p.Arg19Gly) mutation using whole-exome sequencing and fibrin structure analysis. Our family is the first reported carrying the p.Arg19Gly mutation combined with one or more single nucleotide polymorphisms (SNP)s in FGA, FGB, and/or FGG and increased fibrin fiber thickness and fibrin mass-to-length ratio suffering from pulmonary emboli, suggesting that compound genotypes may contribute to the thrombogenic phenotype of these patients. Our review, accordingly, focuses on significance of SNPs, compound genotypes, and fibrin structure measures affecting the genotype-phenotype associations in fibrinogen knob A mutations.

A critical role for plasminogen in inflammation

Plasminogen and its active form, plasmin, have diverse functions related to the inflammatory response in mammals. Due to these roles in inflammation, plasminogen has been implicated in the progression of a wide range of diseases with an inflammatory component. In this review, we discuss the functions of plasminogen in inflammatory regulation and how this system plays a role in the pathogenesis of diseases spanning organ systems throughout the body.

Association of a Variant in VWA3A with Response to Anti-Vascular Endothelial Growth Factor Treatment in Neovascular AMD

Purpose

Anti–vascular endothelial growth factor (VEGF) therapy for neovascular AMD (nvAMD) obtains a variable outcome. We performed a genome-wide association study for anti-VEGF treatment response in nvAMD to identify variants potentially underlying such a variable outcome.

Methods

Israeli patients with nvAMD who underwent anti-VEGF treatment (n = 187) were genotyped on a whole exome chip containing approximately 500,000 variants. Genotyping was correlated with delta visual acuity (deltaVA) between baseline and after three injections of anti-VEGF. Top principal components, age, and baseline VA were included in the analysis. Two lead associated variants were genotyped in an independent validation set of patients with nvAMD (n = 108).

Results

Linear regression analysis on 5,353,842 variants revealed five exonic variants with an association P value of less than 6 × 10⁻⁵. The top variant in the gene VWA3A (P = 1.77 × 10⁻⁶) was tested in the validation cohort. The minor allele of the VWA3A variant was associated with worse response to treatment (P = 0.02). The average deltaVA of discovery plus validation was –0.214 logMAR (≈ a gain of 10.7 Early Treatment Diabetic Retinopathy Study letters) for homozygote for the major allele, 0.172 logMAR for heterozygotes (≈ a loss of 8.6 Early Treatment Diabetic Retinopathy Study letters), and 0.21 logMAR for homozygote for the minor allele (≈ a loss of 10.5 Early Treatment Diabetic Retinopathy Study letters). Minor allele carriers had a higher frequency of macular hemorrhage at baseline.

Conclusions

An VWA3A gene variant was associated with worse response to anti-VEGF treatment in Israeli patients with nvAMD. The VWA3A protein is a precursor of the multimeric von Willebrand factor which is involved in blood coagulation, a system previously associated with nvAMD.

Inflammation and Endothelial Function Relevant Genetic Polymorphisms and Carotid Plaque in Chinese Population

Aim: To examine the association between carotid plaque and variants in genes involved in inflammation and endothelial function.

Methods: This was a multicenter, cross-sectional survey in southwestern China. The residents aged ≥ 40 years volunteered to participate in the face-to-face survey in eight communities. A total of 2,377 subjects with high stroke risk were enrolled. Carotid plaque and plaque phenotype were assessed by carotid ultrasound. Genotypes of 19 variants in 10 genes related to inflammation and endothelial function were examined. Gene-gene interaction was analyzed by generalized multifactor dimensionality reduction (GMDR).

Results: Carotid plaques were found in 852 (35.8%) subjects, and 454 (53.3%) had stable plaques, whereas 398 (46.7%) had vulnerable plaques. PPARA rs4253655, HABP2 rs7923349, and IL1A rs1609682 were associated with the presence of carotid plaque, and NOS2A rs2297518 and PPARA rs4253655 were associated with vulnerable plaque in univariate analysis. The GMDR analysis revealed that there was a significant gene–gene interaction among HABP2 rs7923349, ITGA2 rs1991013, IL1A rs1609682, and NOS2A rs8081248, and the high-risk interactive genotype among the four variants was independently associated with a higher risk of carotid vulnerable plaque after adjusting the covariates (OR, 2.86, 95% CI: 1.32–7.13, P = 0.003).

Conclusion: The prevalence of carotid plaque was very high in the high-risk stroke population in southwestern China. Variants in genes involved in the endothelial function and inflammation were associated with the carotid plaque. The high-risk interactive genotype among rs7923349, rs1991013, rs1609682, and rs8081248 was independently associated with a higher risk of vulnerable plaque.

VEGF-A-Cleavage by FSAP and Inhibition of Neo-Vascularization

Alternative splicing leads to the secretion of multiple forms of vascular endothelial growth factor-A (VEGF-A) that differ in their activity profiles with respect to neovascularization. FSAP (factor VII activating protease) is the zymogen form of a plasma protease that is activated (FSAPa) upon tissue injury via the release of histones. The purpose of the study was to determine if FSAPa regulates VEGF-A activity in vitro and in vivo. FSAP bound to VEGF₁₆₅, but not VEGF₁₂₁, and VEGF₁₆₅ was cleaved in its neuropilin/proteoglycan binding domain. VEGF₁₆₅ cleavage did not alter its binding to VEGF receptors but diminished its binding to neuropilin. The stimulatory effects of VEGF₁₆₅ on endothelial cell proliferation, migration, and signal transduction were not altered by FSAP. Similarly, proliferation of VEGF receptor-expressing BAF3 cells, in response to VEGF₁₆₅, was not modulated by FSAP. In the mouse matrigel model of angiogenesis, FSAP decreased the ability of VEGF₁₆₅, basic fibroblast growth factor (bFGF), and their combination, to induce neovascularization. Lack of endogenous FSAP in mice did not influence neovascularization. Thus, FSAP inhibited VEGF₁₆₅-mediated angiogenesis in the matrigel model in vivo, where VEGF’s interaction with the matrix and its diffusion are important.

Genetic determinants of activity and antigen levels of contact system factors

Essentials Genetic variation may provide valuable insight into the role of the contact system in thrombosis. Explored associations of genetic variants with activity, antigen, and disease in RATIO study. Two novel loci were identified: KLKB1 rs4253243 for prekallikrein; KNG1 rs5029980 for HMWK levels. Contact system variants and haplotypes were not associated with myocardial infarction or stroke. SUMMARY: Background The complex, interdependent contact activation system has been implicated in thrombotic disease, although few genetic determinants of levels of proteins from this system are known. Objectives Our primary aim was to study the influence of common F11, F12, KLKB1, and KNG1 variants on factor (F) XI activity and FXI, FXII, prekallikrein (PK) and high-molecular-weight kininogen (HMWK) antigen levels, as well as the risk of myocardial infarction and ischemic stroke. Patients/methods We analyzed samples from all 630 healthy participants, 182 ischemic stroke patients and 216 myocardial infarction patients in the RATIO case-control study of women aged < 50 years. Forty-three tagging single nucleotide variants (SNVs) were genotyped to represent common genetic variation in the contact system genes. Antigen and activity levels were measured with sandwich-ELISA-based and one-stage clotting assays. We performed single variant, age-adjusted, linear regression analyses per trait and disease phenotype, assuming additive inheritance and determined conditionally independent associations. Haplotypes based on the lead SNV and all conditionally independent SNVs were tested for association with traits and disease. Results We identified two novel associations of KLKB1 SNV rs4253243 with PK antigen (βconditional = -12.38; 95% CI, -20.07 to -4.69) and KNG1 SNV rs5029980 with HMWK antigen (βconditional = 5.86; 95% CI, 2.40-9.32) and replicated previously reported associations in a single study. Further analyses probed whether the observed associations were indicative of linkage, pleiotropic effects or mediation. No individual SNVs or haplotypes were associated with the disease outcomes. Conclusion This study adds to current knowledge of how genetic variation influences contact system protein levels and clarifies interdependencies.

Factor VII activating protease

Factor VII activating protease (FSAP) is a circulating serine protease with high homology to fibrinolytic enzymes. A role in the regulation of coagulation and fibrinolysis is suspected based on in vitro studies demonstrating activation of FVII or pro-urokinase plasminogen activator (uPA). However, considering the paucity of any studies in animal models or any correlative studies in humans the role of FSAP in haemostasis remains unclear. In relation to vascular remodeling processes or inflammation it has been convincingly shown that FSAP interacts with growth factors as well as protease activated receptors (PAR). Against this sparse background there are a plethora of studies which have investigated the linkage of single nucleotide polymorphisms (SNP) in the FSAP gene (HABP2) to various diseases. The G534E SNP of FSAP is associated with a low proteolytic activity due to an amino acid exchange in the protease domain. This and other SNPs have been linked to carotid stenosis, stroke as well as thrombosis in the elderly and plaque calcification. These SNP analyses indicate an important role for FSAP in the regulation of the haemostasis system as well as fibroproliferative inflammatory processes.

Analysis of the substrate specificity of Factor VII activating protease (FSAP) and design of specific and sensitive peptide substrates

Factor VII (FVII) activating protease (FSAP) is a circulating serine protease that is likely to be involved in a number of disease conditions such as stroke, atherosclerosis, liver fibrosis, thrombosis and cancer. To date, no systematic information is available about the substrate specificity of FSAP. Applying phage display and positional scanning substrate combinatorial library (PS-SCL) approaches we have characterised the specificity of FSAP towards small peptides. Results were evaluated in the context of known protein substrates as well as molecular modelling of the peptides in the active site of FSAP. The representative FSAP-cleaved sequence obtained from the phage display method was Val-Leu-Lys-Arg-Ser (P4-P1'). The sequence X-Lys/Arg-Nle-Lys/Arg (P4-P1) was derived from the PS-SCL method. These results show a predilection for cleavage at a cluster of basic amino acids on the nonprime side. Quenched fluorescent substrate (Ala-Lys-Nle-Arg-AMC) (amino methyl coumarin) and (Ala-Leu-Lys-Arg-AMC) had a higher selectivity for FSAP compared to other proteases from the hemostasis system. These substrates could be used to measure FSAP activity in a complex biological system such as plasma. In histone-treated plasma there was a specific activation of pro-FSAP as validated by the use of an FSAP inhibitory antibody, corn trypsin inhibitor to inhibit Factor XIIa and hirudin to inhibit thrombin, which may account for some of the haemostasis-related effects of histones. These results will aid the development of further selective FSAP activity probes as well as specific inhibitors that will help to increase the understanding of the functions of FSAP in vivo.

Factor 11 single-nucleotide variants in women with heavy menstrual bleeding

In a previous study it was shown that lower factor XI (FXI) levels in women with heavy menstrual bleeding (HMB). Our aim was to determine the single-nucleotide variants (SNVs) in the F11 gene in women with HMB. In addition, an extensive literature search was performed to determine the clinical significance of each SNV. Patients referred for HMB (PBAC-score >100) were included. With direct sequencing analysis of all 15 exons and flanking introns of the F11 gene, 29 different non-structural SNVs were detected in 49 patients with HMB. Interestingly, most of these SNVs have previously been associated with venous thrombosis instead of bleeding. These findings have not helped to elucidate the molecular basis of HMB. They also question the specificity of previously reported F11 variations in patients with thrombosis. More studies are needed to explain the lower FXI levels seen in patients with HMB. IMPACT STATEMENT Women with mild deficiencies of factor XI (FXI) (< 70%) are prone to excessive bleeding during menstruation. Bleeding manifestations are not well correlated with plasma FXI levels and bleeding episodes can vary widely among patients with similar low FXI levels. In a previous study we showed that women with heavy menstrual bleeding (HMB) had normal, but on average, lower levels of FXI than controls. In light of these findings, we performed F11 gene analysis to determine the single-nucleotide variants (SNVs) in women with HMB and performed an extensive literature search to determine the clinical significance of each SNV. By direct sequencing analysis of the F11 gene we found 29 different non-structural SNVs in 49 women with heavy menstrual bleeding. Remarkably, a number of these SNVs have previously been implicated in thrombosis. These findings have not helped to elucidate the molecular basis of lower FXI levels in HMB. They also question the specificity of previously reported F11 variations in patients with thrombosis. More studies are needed to explain the lower FXI levels seen in patients with HMB.

Venous thromboembolism in the elderly

Old age is an independent risk factor of venous thromboembolism. Nevertheless initial symptoms are often attributed to existing cardiac or pulmonary comorbidity. Once deep thromboembolism (DTE) is in focus, the synopsis of clinical findings and anamnestic clues help to take further steps to establish or rule out the diagnosis (e.g. Wells score). Treatment consists in oral anticoagulation, either by vitamin-k-antagonists or by direct oral anticoagulants (“DOACs”). Strict compliance of patients or main caregivers is essential in both cases. Simultaneous medication of platelet-inhibitingor nonsteroidal anti-inflammatory drugs – often unknown self medication – results in a raised bleeding risk and should be avoided. If longterm anticoagulation is mandatory, a strategy of sequential dose-reduced anticoagulation can be considered, especially in the case of increased bleeding-risk. Systemic fibrinolysis of pulmonary embolism goes along with a very high bleeding risk in old age and should be performed only in case of vital circulatory depression or failure.

A genetic risk score comprising known venous thromboembolism loci is associated with chronic venous disease in a multi-ethnic cohort

BACKGROUND

Chronic venous disease is common and shares some risk factors with venous thromboembolism (VTE). Several genetic loci have been discovered and well-replicated for VTE in European descent populations. We examined associations of a genetic risk score (GRS), comprising known VTE loci, with chronic venous disease.

METHODS

The San Diego Population Study (SDPS) is a multi-ethnic cohort that evaluated 2404 men and women aged 29-91 from 1994 to 1998 for chronic venous disease. The current study includes 1447 participants genotyped for 33 variants in 22 established VTE risk loci. Using these variants, unweighted and weighted GRS were constructed. Logistic regression was used to examine associations with venous disease.

RESULTS

In non-Hispanic whites, African-Americans, Hispanics, and Asians, each standard deviation increment higher of the unweighted 33-SNP GRS was associated with a 1.45-fold (95% CI (1.26, 1.67)), 1.74-fold (1.18, 2.55), a 1.80-fold (1.30, 2.51), and 1.88-fold (1.30, 2.73) greater odds, respectively, for moderate plus severe disease. The difference in c-statistics was significant between a known venous risk factor model and a model adding the 33-SNP GRS for whites (p=0.008), African-Americans (0.03), and Hispanics (p=0.04), with marginal significance in Asians (p=0.06).

CONCLUSIONS

GRS comprising variants primarily from VTE findings in European descent populations were associated with chronic venous disease across all race/ethnic groups, and contributed significantly to prediction, indicating some level of generalizability to other race/ethnic groups. Future work should focus on more in depth examination of racial/ethnic group genetic architecture in relation to chronic venous disease.

Haemostaseome-associated SNPs: has the thrombotic phenotype a greater influence than ethnicity? GMT study from Aquitaine including Basque individuals

The Genetic Markers for Thrombosis (GMT) study compared the relative influence of ethnicity and thrombotic phenotype regarding the distribution of SNPs implicated in haemostasis pathophysiology ("haemostaseome"). We assessed 384 SNPs in three groups, each of 480 subjects: 1) general population of Aquitaine region (Southwestern France) used as control; 2) patients with venous thromboembolism from the same area; and 3) autochthonous Basques, a genetic isolate, who demonstrate unusual characteristics regarding the coagulation system. This study sought to evaluate i) the value of looking for a large number of genes in order to identify new genetic markers of thrombosis, ii) the value of investigating low risk factors and potential preferential associations, iii) the impact of ethnicity on the characterisation of markers for thrombosis. We did not detect any previously unrecognised SNP significantly associated with thrombosis risk or any preferential associations of low-risk factors in patients with thrombosis. The sum of ϰ² values for our 110 significant SNPs demonstrated a smaller genetic distance between patients and controls (321 cumulated ϰ² value) than between Basques and controls (1,570 cumulated ϰ² value). Hence, our study confirms the genetic particularity of Basques especially regarding a significantly lower expression of the non-O blood group (p< 0.0004). This is mitigated by a higher prevalence of factor II Leiden (p< 0.02) while factor V Leiden prevalence does not differ. Numerous other differences covering a wide range of proteins of the haemostaseome may result in an overall different genetic risk for venous thromboembolism.

Activated partial thromboplastin time and anti-xa measurements in heparin monitoring: biochemical basis for discordance

We examined the concordance of heparin levels measured by a chromogenic anti-Xa assay and the activated partial thromboplastin time (APTT) during unfractionated heparin therapy (UFH) and the biochemical basis for differences between these measures. We also investigated the endogenous thrombin potential (ETP) as a possible measure of anticoagulation. Paired measures of anti-Xa and APTT were performed on 569 samples from 149 patients on UFH. The anti-Xa values and the APTT were concordant in only 54% of measurements. One hundred twelve samples from 59 patients on UFH were assayed for APTT, anti-Xa, factor II, factor VIII, and ETP. Supratherapeutic APTT values but therapeutic anti-Xa results had decreased factor II activity. Subtherapeutic APTT but therapeutic anti-Xa values had high factor VIII activity. ETP correlated with anticoagulation status and UFH dose. In conclusion, factor II and VIII activity contributes to discordance between APTT and anti-Xa results. ETP measurements may provide an additional assessment of anticoagulation status.

Nicotine modulation of factor VII activating protease (FSAP) expression in human monocytes

AIM

Factor VII activating protease (FSAP) is a plasma serine protease involved in hemostasis and remodeling processes. Increased levels of circulating FSAP during pregnancy and in women using oral contraceptives (OCs) indicate that the hormonal status critically influences FSAP expression. In this respect, the aim of this study was to quantify nicotine modulation of FSAP expression in human monocytes/macrophages isolated from healthy female smokers and non-smokers, and from women who use OCs and smoke.

METHODS

FSAP concentration and activity were measured in plasma samples obtained from healthy non-pregnant, pre-menopausal, non-smoking women who did not use OCs (n=69), non-pregnant, pre-menopausal women who currently smoke and use OCs (n=43), and women who are only smokers (n=40) or currently use OCs (n=48). Expressions of FSAP mRNA and protein in monocytes isolated from healthy non-pregnant female or healthy male donors were analyzed.

RESULTS

Strongest circulating FSAP concentration and activity occurred in women with combined smoking and use of OCs compared to the control group. Enhanced FSAP levels were also observed in smoking women when compared to non-smokers. Ex vivo experiments demonstrated enhanced FSAP expression in monocytes isolated from women using OCs and currently smoking. Nicotine enhanced FSAP mRNA and protein levels in monocytes.

CONCLUSIONS

Monocytes from healthy female smokers show a constitutively enhanced FSAP expression and this effect could be replicated in vitro by stimulating monocytes with nicotine. The upregulation of FSAP due to nicotine and OC usage may be linked to a higher incidence of arteriothromboembolic diseases related to their usage.

A genome-wide association study identifies KNG1 as a genetic determinant of plasma factor XI Level and activated partial thromboplastin time

OBJECTIVE

Elevated plasma levels of coagulation factor XI (FXI) are implicated in the pathogenesis of venous thromboembolism and ischemic stroke, and polymorphisms in the F11 gene are associated both with risk of venous thromboembolism and an elevated plasma FXI level.

METHODS AND RESULTS

Here, we report the first hypothesis-free genome-wide genetic analysis of plasma FXI levels. Two genome-wide significant loci were detected in the family-based Genetic Analysis of Idiopathic Thrombophilia 1 cohort: one located in the kininogen 1 gene (KNG1) (rs710446; P=7.98 × 10(-10)) and one located in the structural F11 gene (rs4241824; P=1.16 × 10(-8)). Both associations were replicated in a second population-based Swedish cohort. A significant effect on KNG1 mRNA expression was also seen for the 2 most robustly FXI-associated single nucleotide polymorphisms located in KNG1. Furthermore, both KNG1 single nucleotide polymorphisms were associated with activated partial thromboplastin time, suggesting that FXI may be the main mechanistic pathway by which KNG1 and F11 influence activated partial thromboplastin time and risk of thrombosis.

CONCLUSIONS

These findings contribute to the emerging molecular basis of venous thromboembolism and, more importantly, help in understanding the biological regulation of a phenotype that has proved to have promising therapeutic properties in relation to thrombosis.

Factor v leiden and inflammation

Factor V Leiden, is a variant of human factor V (FV), also known as proaccelerin, which leads to a hypercoagulable state. Along these years, factor V Leiden (FVL) has been studied from the pathophysiologic point of view, and research has been focused on finding clinical approaches for the management of the FVL associated to a trombophilic state. Less attention has been paid about the possible role of FVL in inflammatory conditions known to be present in different disorders such as uremia, cirrhosis, liver transplantation, depression as well as sepsis, infection or, inflammatory bowel disease (IBD). Whether platelet FVL will increase the activation of coagulation and/or in which proportion is able to determine the final outcome in the previously mentioned inflammatory conditions is a subject that remains uncertain. This paper will review the association of FVL with inflammation. Specifically, it will analyze the important role of the endothelium and the contribution of other inflammatory components involved at both the immune and vascular levels. This paper will also try to emphasize the importance of being a FVL carrier in associations to diseases where a chronic inflammation occurs, and how this condition may be determinant in the progression and outcome of a specific clinic situation.

Plasma factor VII-activating protease antigen levels and activity are increased in ischemic stroke

BACKGROUND

Factor VII-activating protease (FSAP) is a recently discovered plasma protease with a role in the regulation of hemostasis and vascular remodeling processes. Higher levels and activity of FSAP have been reported in patients with deep vein thrombosis, but there are no data on plasma FSAP in ischemic stroke (IS).

OBJECTIVE

To investigate whether FSAP antigen levels and activity are associated with IS and/or etiologic subtypes of IS.

PATIENTS AND METHODS

To assess the potential association between FSAP and IS, plasma FSAP antigen levels and activity were measured in 600 consecutive IS patients and 600 population-based controls from the case-control study the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS). Blood sampling was performed in the acute phase and 3 months after the index stroke. FSAP was also investigated at the genetic level by genotyping of 33 single-nucleotide polymorphisms.

RESULTS

Increased FSAP antigen level and activity, at both time-points, were independently associated with IS. Subtype analysis revealed similar associations for both FSAP measures, at both time-points, in all main IS subtypes. FSAP genotypes showed association with both FSAP plasma measurements, but not with IS.

CONCLUSIONS

Increased plasma FSAP antigen levels and activity were associated with IS and all main etiologic subtypes, suggesting a possible role for FSAP in the pathophysiology of IS, irrespective of the underlying etiology.

Candidate gene polymorphisms and the risk for pregnancy-related venous thrombosis

Venous thrombosis (VT) is one of the leading causes of maternal death in the western world, but the genetic causes of pregnancy-related VT are insufficiently understood. The aim of this study was to investigate the association between common genetic variations in candidate genes and pregnancy-related VT. We undertook a hospital based case-control study of women with VT during pregnancy or puerperium; controls were women giving birth without having VT. Single nucleotide polymorphisms (SNPs) were selected in 49 pre-specified candidate genes involved in coagulation, inflammation, and hormonal metabolism in 313 cases and 353 controls. We found new associations between SNPs and total pregnancy-related VT in the genes encoding coagulation factors V and VIII, and p-selectin. Additional new associations between SNPs and antenatal VT were found in the genes encoding the epidermal growth factor receptor, the pregnane X receptor, and protein S. Of 21 SNPs previously associated with thrombotic disease, rs2289252 in F11 and rs3917643 in F3 were associated with pregnancy-related VT, while rs4524 in F5 was associated with antenatal VT.

von Willebrand factor genetic variant associated with hematoma expansion after intracerebral hemorrhage

BACKGROUND

Hematoma expansion, the leading cause of neurologic deterioration after intracerebral hemorrhage (ICH), remains one of the few modifiable risk factors for poor outcome. In the present study, we explored whether common genetic variants within the hemostasis pathway were related to hematoma expansion during the acute period after ICH.

METHODS

Patients with spontaneous ICH who were admitted to the institutional Neuro-ICU between 2009 and 2011 were enrolled in the study, and clinical data were collected prospectively. Hematoma size was measured in patients admitted on or before postbleed day 2. Baseline models for hematoma growth were constructed using backwards stepwise logistic regression. Genotyping of single-nucleotide polymorphisms for 13 genes involved in hemostasis was performed, and the results were individually included in the above baseline models to test for independent association of hematoma expansion.

RESULTS

During the study period, 82 patients were enrolled in the study and had complete data. The mean age was 65.9 ± 14.9 years, and 38% were female. Only von Willebrand factor was associated with absolute and relative hematoma growth in univariate analysis (P < .001 and P = .007, respectively); von Willebrand factor genotype was independently predictive of relative hematoma growth but only approached significance for absolute hematoma growth (P = .002 and P = .097, respectively).

CONCLUSIONS

Our genomic analysis of various hemostatic factors identified von Willebrand factor as a potential predictor of hematoma expansion in patients with ICH. The identification of von Willebrand factor single-nucleotide polymorphisms may allow us to better identify patients who are at risk for hematoma enlargement and will benefit the most from treatment. The relationship of von Willebrand factor with regard to hematoma enlargement in a larger population warrants further study.

Factor VII-activating protease promotes the proteolysis and inhibition of tissue factor pathway inhibitor

OBJECTIVE

Factor VII-activating protease (FSAP) activates both factor VII and pro-urokinase and inhibits platelet-derived growth factor-BB, thus regulating hemostasis- and remodeling-associated processes in the vasculature. A genetic variant of FSAP (Marburg I polymorphism) results in low enzymatic activity and is associated with an enhanced risk of carotid stenosis and stroke. We postulate that there are additional substrates for FSAP that will help to explain its role in vascular biology and have searched for such a substrate.

METHODS AND RESULTS

Using screening procedures to determine the influence of FSAP on various hemostasis-related processes on endothelial cells, we discovered that FSAP inhibited tissue factor pathway inhibitor (TFPI), a major anticoagulant secreted by these cells. Proteolytic degradation of TFPI by FSAP could also be demonstrated by Western blotting, and the exact cleavage sites were determined by N-terminal sequencing. The Marburg I variant of FSAP had a diminished ability to inhibit TFPI. A monoclonal antibody to FSAP that specifically inhibited FSAP binding to TFPI reversed the inhibitory effect of FSAP on TFPI.

CONCLUSIONS

The identification of TFPI as a sensitive substrate for FSAP increases our understanding of its role in regulating hemostasis and proliferative remodeling events in the vasculature.

Racial differences in venous thromboembolism

The incidence of venous thrombosis (VTE) varies by race, with African-Americans having over 5-fold greater incidence than Asian-ancestry populations, and an intermediate risk for European and Hispanic populations. Known racial differences in genetic polymorphisms associated with thrombosis do not account for this gradient of risk, nor do known racial variations in environmental risk factors. Data on the incidence of and risk factors for VTE outside of Europe and North America and in non-European ancestry populations are sparse. Common genetic polymorphisms in European-Ancestry populations, such as factor V Leiden and prothrombin G20210A, and environmental risk factors, such as obesity, may account for some of the increased risk in European populations, and high factor VIII, high von Willebrand factor and low protein C levels and increased prevalence of obesity may explain some of the increased risk in African-Americans. The low rates in Asian populations may be partially explained by low clinical suspicion in a perceived low-risk population and lack of access to healthcare in other populations. As risk factors for thrombosis, such as surgery and treatment for cancer, are applicable to more people, as obesity increases in prevalence in the developing world, and as surveillance systems for VTE improve, VTE may increase in previously low-risk populations. While differences in VTE by race due to genetic predisposition will probably always be present, understanding the reasons for racial differences in VTE will help providers develop strategies to minimize VTE in all populations.

Genetic variation within the anticoagulant, procoagulant, fibrinolytic and innate immunity pathways as risk factors for venous thromboembolism

BACKGROUND

 Venous thromboembolism (VTE) is highly heritable (estimated heritability [h(2)]=0.62) and likely to be a result of multigenic action.

OBJECTIVE

 To systematically test variation within genes encoding for important components of the anticoagulant, procoagulant, fibrinolytic and innate immunity pathways for an independent association with VTE.

METHODS

 Non-Hispanic adults of European ancestry with objectively-diagnosed VTE, and age- and sex- matched controls, were genotyped for 13 031 single nucleotide polymorphisms (SNPs) within 764 genes. Analyses (n=12296 SNPs) were performed with plink using an additive genetic model and adjusted for age, sex, state of residence, and myocardial infarction or stroke.

RESULTS

Among 2927 individuals, one or more SNPs within ABO, F2, F5, F11, KLKB1, SELP and SCUBE1 were significantly associated with VTE, including factor (F) V Leiden, prothrombin G20210A, ABO non-O blood type, and a novel association with ABO rs2519093 (OR=1.68, P-value=8.08×10(-16) ) that was independent of blood type. In stratified analyses, SNPs in the following genes were significantly associated with VTE: F5 and ABO among both genders and LY86 among women; F2, ABO and KLKB1 among FV Leiden non-carriers; F5, F11, KLKB1 and GFRA1 in those with ABO non-O blood type; and ABO, F5, F11, KLKB1, SCUBE1 and SELP among prothrombin G20210A non-carriers. The ABO rs2519093 population-attributable risk (PAR) exceeded that of FV Leiden and prothrombin G20210A, and the joint PAR of FV Leiden, prothrombin G20210A, ABO non-O and ABO rs2519093 was 0.40.

CONCLUSIONS

Anticoagulant, procoagulant, fibrinolytic and innate immunity pathway genetic variation accounts for a large proportion of VTE among non-Hispanic adults of European ancestry.

Genome-wide association study of blood pressure response to methylphenidate treatment of attention-deficit/hyperactivity disorder

OBJECTIVE

We conducted a genome-wide association study of blood pressure in an open-label study of the methylphenidate transdermal system (MTS) for the treatment of attention-deficit/hyperactivity disorder (ADHD).

METHOD

Genotyping was conducted with the Affymetrix Genome-Wide Human SNP Array 6.0. Multivariate association analyses were conducted using the software package PLINK. After data cleaning and quality control we tested 316,934 SNPs in 140 children with ADHD.

RESULTS

We observed no genome-wide statistically significant findings, but a SNP in a K(+)-dependent Na(+)/Ca(2+) exchanger expressed in vascular smooth muscle (SLC24A3) was included in our top associations at p<1E-04. Genetic enrichment analyses of genes with ≥1 SNP significant at p<0.01, implicated several functional categories (FERM domain, p=5.0E-07; immunoglobulin domain, p=8.1E-06; the transmembrane region, p=4.4E-05; channel activity, p=2.0E-04; and type-III fibronectins, p=2.7E-05) harboring genes previously associated with related cardiovascular phenotypes.

CONCLUSIONS

The hypothesis generating results from this study suggests that polymorphisms in several genes consistently associated with cardiovascular diseases may impact changes in blood pressure observed with methylphenidate pharmacotherapy in children with ADHD.

Carotid plaque and candidate genes related to inflammation and endothelial function in Hispanics from northern Manhattan

BACKGROUND AND PURPOSE

The genetic influence on carotid atherosclerotic plaque is mostly unknown. This study examines the association between carotid plaque and single nucleotide polymorphisms in selected genes implicated in inflammation and endothelial function.

METHODS

A total of 43 genes (197 single nucleotide polymorphisms) involved in inflammation and endothelial function were interrogated in 287 Dominicans from the Northern Manhattan Study (mean age, 64±7 years; 58% women) who had undergone high-resolution B-mode ultrasound for examination of carotid plaque. Using an additive genetic model, multiple logistic regression analyses were conducted, a within-gene haplotype analysis was performed, and interactions between genes were examined. Results were validated in an independent set of 301 Dominicans.

RESULTS

Carotid plaque was present in 143 (47%) participants. Nine genes had at least 1 single nucleotide polymorphism associated (P≤0.01) with carotid plaque phenotypes: TNF, NOS2A, IL6R, TNFSF4, PPARA, IL1A, TLR4, ITGA2, and HABP2. Single nucleotide polymorphisms in TNFSF4, PPARA, TLR4, ITGA2, and HABP2 were also implicated with the same carotid phenotype in the validation analysis. Haplotype analysis revealed an additional gene of interest, VCAM1.

CONCLUSIONS

We report novel associations between variations in 10 genes involved in inflammation and endothelial function and carotid plaque phenotypes in a Dominican sample, with replication for 5 genes in an independent Dominican sample.

Association of coagulation-related and inflammation-related genes and factor VIIc levels with stroke: the Cardiovascular Health Study

BACKGROUND

Thrombosis and inflammation are critical in stroke etiology, but associations of coagulation and inflammation gene variants with stroke, and particularly factor VII levels, are inconclusive.

OBJECTIVES

To test the associations between 736 single-nucleotide polymorphisms (SNPs) between tagging haplotype patterns of 130 coagulation and inflammation genes, and stroke events, in the 5888 participants aged ≥ 65 years of the observational Cardiovascular Health Study cohort.

PATIENTS/METHODS

With 16 years of follow-up, age-adjusted and sex-adjusted Cox models were used to estimate associations of SNPs and FVIIc levels with future stroke.

RESULTS

Eight hundred and fifteen strokes occurred in 5255 genotyped participants without baseline stroke (748 ischemic strokes; 586 among whites). Among whites, six SNPs were associated with stroke, with a nominal P-value of < 0.01: rs6046 and rs3093261 (F7); rs4918851 and rs3781387 (HABP2); and rs3138055 (NFKB1A) and rs4648004 (NFKB1). Two of these SNPs were associated with FVIIc levels (units of percentage activity): rs6046 (β = -18.5, P = 2.38 × 10(-83)) and rs3093261 (β = 2.99, P = 3.93 × 10(-6)). After adjustment for age, sex, race, and cardiovascular risk factors, the association of FVIIc quintiles (Q) with stroke were as follows (hazard ratio; 95% confidence interval): Q1, reference; Q2, 1.4, 1.1-1.9); Q3, 1.1, 0.8-1.5); Q4, 1.5, 1.1-2.0); and Q5, 1.6, 1.2-2.2). Associations between SNPs and stroke were independent of FVIIc levels.

CONCLUSIONS

Variations in FVII-related genes and FVIIc levels were associated with risk of incident ischemic stroke in this elderly cohort, suggesting a potential causal role for FVII in stroke etiology.

Functional polymorphisms of the coagulation factor II gene (F2) and susceptibility to systemic lupus erythematosus

OBJECTIVE

Two F2 functional polymorphisms, rs1799963 (G20210A) and rs3136516 (A19911G), are known to be associated with elevated levels/activity of prothrombin (encoded by F2) and risk of thrombosis. Since patients with systemic lupus erythematosus (SLE) have high risk of thrombosis and accelerated atherosclerosis and also high prevalence of anti-prothrombin antibodies, we hypothesized that these two F2 polymorphisms could affect risk of SLE.

METHODS

We investigated these polymorphisms in 627 women with SLE (84% Caucasian Americans, 16% African Americans) and 657 female controls (78% Caucasian Americans, 22% African Americans).

RESULTS

While the rs1799963 A allele was almost absent in African Americans, it was present at ~2% frequency in Caucasian Americans and showed no significant association with SLE. The rs3136516 G allele frequency was significantly higher in Caucasian SLE cases than in controls (48.4% vs 43.7%, respectively) with a covariate-adjusted odds ratio (OR) of 1.22 (95% CI 1.03-1.46, p = 0.023). The association was replicated in African Americans (rs3136516 G allele frequency 91.2% in cases vs 82.2% in controls) with an adjusted OR of 1.96 (95% CI 1.08-3.58, p = 0.022). Stratification of Caucasian SLE patients based on the presence or absence of cardiac and vascular events (CVE) revealed stronger association with the CVE-positive SLE subgroup than the CVE-negative SLE subgroup (OR 1.42 vs 1.20). Prothrombin activity measurements in a subset of SLE cases demonstrated higher activity in the carriers of the rs3136516 G allele.

CONCLUSION

Our results suggest a potential role for prothrombin and the crosstalk between hemostatic and immune/inflammatory systems in SLE and SLE-associated cardiovascular events, which warrants further investigation in independent samples.

A multi-stage multi-design strategy provides strong evidence that the BAI3 locus is associated with early-onset venous thromboembolism

BACKGROUND

Factor VIII (FVIII) and von Willebrand factor (VWF) are two known quantitative risk factors for venous thromboembolism (VTE).

OBJECTIVES

To identify new loci that could contribute to VTE susceptibility and to modulating FVIII and/or VWF levels.

PATIENTS/METHODS

A pedigree linkage analysis was first performed in five extended French-Canadian families, including 253 individuals, to identify genomic regions linked to FVIII or VWF levels. Identified regions were further explored using 'in silico' genome-wide association studies (GWAS) data on VTE (419 patients and 1228 controls), and two independent case-control studies (MARTHA and FARIVE) for VTE, gathering 1166 early-onset patients and 1408 healthy individuals. Single nucleotide polymorphisms (SNPs) associated with VTE risk were further investigated in relation to plasma levels of FVIII and VWF in a cohort of 108 healthy nuclear families.

RESULTS

Four main linkage regions were identified, among which the well-characterized ABO locus, the recently identified STAB 2 gene, and a third one, on chromosome 6q13-14, harbouring four non-redundant SNPs, associated with VTE at P < 10(-4) in the GWAS dataset. The association of one of these SNPs, rs9363864, with VTE was further replicated in the MARTHA and FARIVE studies. The rs9363864-AA genotype was associated with a lower risk for VTE (OR = 0.58 [0.42-0.80], P = 0.0005) but mainly in non-carriers of the FV Leiden mutation. This genotype was further found to be associated with the lowest levels of FVIII (P = 0.006) and VWF (P = 0.001).

CONCLUSIONS

The BAI3 locus where the rs9363864 maps is a new candidate for VTE risk.

Factor seven ativating potease (FSAP) levels during normal pregnancy and in women using oral contraceptives

INTRODUCTION

Factor seven activating protease (FSAP) is a plasma serine protease involved in haemostasis and remodeling processes. We have investigated whether pregnancy or the use of oral contraceptives (OCs) influences circulating FSAP levels. The effect of female sex hormones on FSAP expression in cultured cells was also determined.

MATERIALS AND METHODS

FSAP levels and activity was measured in plasma samples obtained at different gestation stages from healthy pregnant women (n=101), from non-pregnant women, pre-menopausal women who currently use OCs (n=48), and non-pregnant women who did not use OCs (n=69).

RESULTS

In late pregnancy the plasma FSAP antigen (median 2.28 PEU/ml [range 1.11 to 2.62 PEU/ml]; p<0.001 vs control group) and activity (median 2.98 PEU/ml [range 1.05 to 4.24 PEU/ml]; p<0.001 vs control group) was significantly higher compared with levels in non-pregnant women and remained elevated after delivery. Plasma FSAP levels in women using OCs was also significantly elevated compared to the control group. Ex vivo experiments demonstrated enhanced FSAP expression in monocytes isolated from women using OCs. In vitro experiments showed that FSAP mRNA levels were strongly induced by estradiol in monocytes but not in hepatocytes.

CONCLUSIONS

Increased levels of circulating FSAP in pregnancy and in women using OCs indicate that hormonal status critically influences FSAP expression. Hormonal influences could be observed in monocytes in vivo and ex-vivo but not in hepatocytes indicating cell-specific regulation. Future studies designed to investigate the role of FSAP in haemostasis and remodeling processes should consider the role of female sex hormones on FSAP expression.

C4BPB/C4BPA is a new susceptibility locus for venous thrombosis with unknown protein S-independent mechanism: results from genome-wide association and gene expression analyses followed by case-control studies

Through its binding with protein S (PS), a key element of the coagulation/fibrinolysis cascade, the C4b-binding protein (C4BP) has been hypothesized to be involved in the susceptibility to venous thrombosis (VT). To identify genetic factors that may influence the plasma levels of the 3 C4BP existing isoforms, alpha(7)beta(1), alpha(6)beta(1), and alpha(7)beta(0), we conducted a genome-wide association study by analyzing 283 437 single nucleotide polymorphisms (SNPs) in the Genetic Analysis of Idiopathic Thrombophilia (GAIT) study composed of 352 persons. Three SNPs at the C4BPB/C4BPA locus were found genome-wide significantly associated with alpha(7)beta(0) levels. One of these SNPs was further found to explain approximately 11% of the variability of mRNA C4BPA expression in the Gutenberg Heart Study composed of 1490 persons, with no effect on C4BPB mRNA expression. The allele associated with increased alpha(7)beta(0) plasma levels and increased C4BPA expression was further found associated with increased risk of VT (odds ratio [OR] = 1.24 [1.03-1.53]) in 2 independent case-control studies (MARseille THrombosis Association study [MARTHA] and FActeurs de RIsque et de récidives de la maladie thromboembolique VEineuse [FARIVE]) gathering 1706 cases and 1379 controls. This SNP was not associated with free PS or total PS. In conclusion, we observed strong evidence that the C4BPB/C4BPA locus is a new susceptibility locus for VT through a PS-independent mechanism that remains to be elucidated.