Fibrinogen gene variation and ischemic stroke

Whole Blood Viscosity and Cerebral Blood Flow in Acute Ischemic Stroke

Existing effective treatments for ischemic stroke restore blood supply to the ischemic region using thrombolysis or mechanical removal of clot. However, it is increasingly recognized that successful removal of occlusive thrombus from the large artery-recanalization, may not always be accompanied by successful restoration of blood flow to the downstream tissues-reperfusion. Ultimately, brain tissue survival depends on cerebral perfusion, and a functioning microcirculation. Because capillary diameter is often equal to or smaller than an erythrocyte, microcirculation is largely dependent on erythrocyte rheological (hemorheological) factors such as whole blood viscosity (WBV). Several studies in the past have demonstrated elevated WBV in stroke compared with healthy controls. Also, elevated WBV has shown to be an independent risk factor for stroke. Elevated WBV leads to endothelial dysfunction, decreases nitric oxide-dependent flow-mediated vasodilation, and promotes hemostatic alterations/thrombosis, all leading to microcirculation sludging. Compromised microcirculation further leads to decreased cerebral perfusion. Hence, modulating WBV through pharmacological agents might be beneficial to improve cerebral perfusion in stroke. This review discusses the effect of elevated WBV on endothelial function, hemostatic alterations, and thrombosis leading to reduced cerebral perfusion in stroke.

The Autosomal Short Tandem Repeat Polymorphisms Are Potentially Associated with Cardiovascular Disease Predisposition in the Latin American Population: A Mini Review

According to the World Health Organization, cardiovascular diseases (CVDs) are the leading cause of death worldwide across nearly all ethnic groups. Inherited cardiac conditions comprise a wide spectrum of diseases that affect the heart, including abnormal structural features and functional impairments. In Latin America, CVDs are the leading cause of death within the region. Factors such as population aging, unhealthy diet, obesity, smoking, and a sedentary lifestyle have increased the risk of CVD. The Latin American population is characterized by its diverse ethnic composition with varying percentages of each ancestral component (African, European, and Native American ancestry). Short tandem repeats (STRs) are DNA sequences with 2-6 base pair repetitions and constitute ~3% of the human genome. Importantly, significant allele frequency variations exist between different populations. While studies have described that STRs are in noncoding regions of the DNA, increasing evidence suggests that simple sequence repeat variations may be critical for proper gene activity and regulation. Furthermore, several STRs have been identified as potential disease predisposition markers. The present review is aimed at comparing and describing the frequencies of autosomal STR polymorphisms potentially associated with cardiovascular disease predisposition in Latin America compared with other populations.

Association between genetic polymorphisms in fibrinogen genes and bleeding risk in patients treated with direct oral anticoagulants

Introduction

This study aimed to investigate the association between polymorphisms in fibrinogen genes and bleeding risk in patients receiving direct oral anticoagulants (DOACs).

Method

Patients treated with DOACs from June 2018 to December 2021 were enrolled in the study. Genotyping was done for rs2070011, rs6050, and rs2070022 in fibrinogen alpha chain (FGA); rs1800788, rs4220, and rs4463047 in fibrinogen beta chain (FGB); and rs2066865 and rs1800792 in fibrinogen gamma chain (FGG), along with F2 rs5896 and F10 rs5960. Multivariable logistic regression analysis was performed to investigate the risk factors for bleeding and to develop a risk scoring system.

Results

A total of 468 patients were included in the analysis, 14 of whom experienced major bleeding and 36 experienced clinically relevant non-major bleeding. In the multivariable analysis, overdose, anaemia, F2 rs5896, and FGG rs1800792 were found to be significantly associated with bleeding risk. Specifically, patients with the TT genotype of F2 rs5896 and the CC genotype of FGG rs1800792 had 2.1 times (95% confidence interval [CI] 1.1-3.9) and 2.7 times (95% CI 1.2-5.9) higher bleeding risk than the C allele and T allele carriers, respectively. Based on the risk scoring system, patients with 0, 1, 2, 3, 4, and 5 points were predicted to have 5.2%, 10.8%, 22.4%, 32.3%, 42.3%, and 61.8% of bleeding risk, respectively.

Conclusion

To our knowledge, this is the first study to investigate the effects of polymorphisms in fibrinogen genes on DOAC response. After validation, these results will be useful for personalised DOAC therapy.

Association of Fibrinogen With Ischemic Stroke: A Systematic Review and Meta-Analysis

Validation of a risk factor in a multifactorial disease like ischemic stroke is necessary to practice precision medicine. Many risk factors have been attributed to causing ischemic stroke but contribute very little to it. There are many risk factors that need to be validated, and fibrinogen is one such risk factor. Using a meta-analysis technique, we investigated fibrinogen as a risk factor for ischemic stroke. We searched the computerized databases such as PubMed, Google Scholar, and Cochrane to explore articles on ischemic stroke. Pooled odds ratios (ORs) with 95% confidence intervals (CIs) were calculated using a random effects model. A total of 10 case-control studies with 6877 cases and 7219 controls were included in the study that match inclusion and exclusion criteria. The Asiatic population was portrayed in four studies, whereas the Caucasian population was portrayed in six studies. Under the recessive model, an elevated level of serum fibrinogen is linked to an increased risk of ischemic stroke as shown by pooled odds ratio (OR: 1.47, 95% CI: 1.19-1.76, I² = 78.3%, P = 0.000). Our meta-analysis concluded that a high level of fibrinogen is associated with an increased risk of ischemic stroke.

Urinary Proteome Analysis of Global Cerebral Ischemia-Reperfusion Injury Rat Model via Data-Independent Acquisition and Parallel Reaction Monitoring Proteomics

Cerebral ischemia–reperfusion (I/R) injury is the leading cause of death in severe hypotension caused by cardiac arrest, drowning, and excessive blood loss. Urine can sensitively reflect pathophysiological changes in the brain even at an early stage. In this study, a rat model of global cerebral I/R injury was established via Pulsinelli’s four-vessel occlusion (4-VO) method. Overall, 164 urinary proteins significantly changed in the 4-VO rat urine samples compared to the control samples by data-independent acquisition (DIA) proteomics technique (1.5-fold change, p < 0.05). Gene Ontology annotation showed that the acute-phase response, the ERK1 and ERK2 cascade, endopeptidase activity, blood coagulation, and angiogenesis were overrepresented. After parallel reaction monitoring (PRM) validation, 15 differential proteins having human orthologs were verified as the potential urinary markers associated with cerebral I/R injury. Of these potential biomarkers, 8 proteins were reported to be closely associated with cerebral I/R injury. Nine differential proteins changed even when there were no clinical manifestations or histopathological cerebral damage, including FGG, COMP, TFF2, HG2A, KNG1, CATZ, PTGDS, PRVA, and HEPC. These 9 proteins are potential biomarkers for early screening of cerebral I/R injury to prevent the development of cerebral injury. KNG1, CATZ, PTGDS, PRVA, and HEPC showed an overall trend of upregulation or downregulation at 12 and 48 h after I/R injury, reflecting the progression of cerebral I/R injury. These 5 proteins may serve as potential biomarkers for prognostic evaluation of cerebral I/R injury. These findings provide important clues to inform the monitoring of cerebral I/R injury and further the current understanding of its molecular biological mechanisms.

Quantitative iTRAQ-based proteomic analysis of piperine protected cerebral ischemia/reperfusion injury in rat brain

Piperine is the key bioactive factor in black pepper, and has been reported to alleviate cerebral ischemic injury. However, the mechanisms underlying its neuroprotective effects following cerebral ischemia remain unclear. In this study, rats were administered vehicle (dimethyl sulfoxide) or piperine, 20 mg/kg, daily for 14 days before focal cerebral artery occlusion. After occlusion for 2 h followed by reperfusion for 24 h. Histological examinations were used to assess whether piperine has a neuroprotective effect in the rat model of cerebral ischemia/reperfusion injury. The levels of proteins in the ischemic penumbra were evaluated by isobaric tags for relative and absolute quantitation-based proteomics. A total of 3687 proteins were identified, including 23 proteins that were highly significantly differentially expressed between the control and piperine groups. The proteomic findings were verified by immunofluorescence and western blot analysis. Interestingly, piperine administration downregulated a number of critical factors in the complement and coagulation cascades, including complement component 3, fibrinogen gamma chain, alpha-2-macroglobulin, and serpin family A member 1. Collectively, our findings suggest that the neuroprotective effects of piperine following cerebral ischemia/reperfusion injury are related to the regulation of the complement and coagulation cascades.

Fibrinogen concentrations predict long-term cognitive outcome in young ischemic stroke patients

BACKGROUND

Cognitive impairment is frequent after stroke, and young patients may live with this consequence for a long time. Predictors of cognitive outcomes after stroke represent a current gap of knowledge.

OBJECTIVES

To investigate levels of three hemostatic biomarkers as predictors of long-term cognitive function after stroke.

METHODS

This longitudinal study included consecutively recruited patients with ischemic stroke at 18-69 years (n = 268). Blood was collected 3 months after index stroke and analyzed for plasma concentrations of fibrinogen, von Willebrand factor (VWF) and tissue-type plasminogen activator (t-PA) antigen. Cognitive function 7 years after index stroke was assessed by the Barrow Neurological Institute Screen for Higher Cerebral Functions (BNIS). Participants with stroke <50 years of age were also examined by the Trail Making Test A and B (n = 41). Associations between biomarker concentrations and cognitive scales were assessed in the whole group and in participants with stroke <50 years of age.

RESULTS

The hemostatic biomarkers fibrinogen, VWF and t-PA, were all correlated to total BNIS score, but these associations did not withstand adjustment for confounding factors in the whole group. However, in patients <50 years, we found an independent association between fibrinogen concentrations and total BNIS score (βstd = -.27, 95% confidence interval [CI], -0.47 to -0.07) and to performance on the Trail Making Test A (βstd = .31, 95% CI, 0.03-0.58). No such association was seen for the Trail Making Test B.

CONCLUSION

High convalescent fibrinogen concentrations were associated with worse long-term cognitive outcomes in ischemic stroke <50 years of age. We propose further investigations of fibrinogen in relation to cognitive function in stroke in the young.

The role of fibrinogen plasma levels, the –455G>A fibrinogen and the factor XIII A subunit (FXIII-A) Val34Leu polymorphism in cancer-associated venous thrombosis

Venous thromboembolism (VTE) is a life-threatening complication in cancer patients. Identification of risk factors has been in focus in the past years. Functional single nucleotide polymorphisms (SNP) of coagulation factors known to influence the concentration or function may be considered to influence the risk of VTE in cancer patients. We evaluated the influence of fibrinogen plasma levels, the –455G>A SNP in the fibrinogen beta gene and the Val34Leu (163G>T) SNP in the factor XIII A-subunit (FXIII-A) gene on the risk of VTE. In 1,079 tumour patients recruited for the prospective Vienna Cancer and Thrombosis Study (CATS) fibrinogen levels were determined by the Clauss method. The FXIII-A Val34Leu and the fibrinogen –455G>A SNPs were tested by allele-specific PCR. The median follow-up time was 604 days, 83 thrombotic events occurred. The median fibrinogen level was 381 mg/dl (25th-75th percentile: 312 to 467). In a multivariable Cox model adjusted to chemotherapy, surgery, radiotherapy, age and sex, neither the fibrinogen concentration (hazard ratio [HR] =1.05, confidence interval [CI] 0.839–1.310 p=0.68), nor the –455G>A SNP (HR=0.77, 95%CI 0.491–1.197; p=0.24), nor the Val34Leu SNP (HR=0.99, 95%CI 0.646–1.542 p=0.99) were associated with occurrence of VTE. The fibrinogen concentration was not significantly different among the fibrinogen –455G or A genotype carriers (p = 0.33). Disseminated intravascular coagulation was observed in only five patients, none of these developed VTE. In conclusion, fibrinogen plasma levels, the fibrinogen –455G>A and the FXIII-A Val34Leu polymorphisms were not associated with VTE in our study.

Biochemical markers in vascular cognitive impairment associated with subcortical small vessel disease - A consensus report

Background

Vascular cognitive impairment (VCI) is a heterogeneous entity with multiple aetiologies, all linked to underlying vascular disease. Among these, VCI related to subcortical small vessel disease (SSVD) is emerging as a major homogeneous subtype. Its progressive course raises the need for biomarker identification and/or development for adequate therapeutic interventions to be tested. In order to shed light in the current status on biochemical markers for VCI-SSVD, experts in field reviewed the recent evidence and literature data.

Method

The group conducted a comprehensive search on Medline, PubMed and Embase databases for studies published until 15.01.2017. The proposal on current status of biochemical markers in VCI-SSVD was reviewed by all co-authors and the draft was repeatedly circulated and discussed before it was finalized.

Results

This review identifies a large number of biochemical markers derived from CSF and blood. There is a considerable overlap of VCI-SSVD clinical symptoms with those of Alzheimer’s disease (AD). Although most of the published studies are small and their findings remain to be replicated in larger cohorts, several biomarkers have shown promise in separating VCI-SSVD from AD. These promising biomarkers are closely linked to underlying SSVD pathophysiology, namely disruption of blood-CSF and blood–brain barriers (BCB-BBB) and breakdown of white matter myelinated fibres and extracellular matrix, as well as blood and brain inflammation. The leading biomarker candidates are: elevated CSF/blood albumin ratio, which reflects BCB/BBB disruption; altered CSF matrix metalloproteinases, reflecting extracellular matrix breakdown; CSF neurofilment as a marker of axonal damage, and possibly blood inflammatory cytokines and adhesion molecules. The suggested SSVD biomarker deviations contrasts the characteristic CSF profile in AD, i.e. depletion of amyloid beta peptide and increased phosphorylated and total tau.

Conclusions

Combining SSVD and AD biomarkers may provide a powerful tool to identify with greater precision appropriate patients for clinical trials of more homogeneous dementia populations. Thereby, biomarkers might promote therapeutic progress not only in VCI-SSVD, but also in AD.

Haemostatic biomarkers are associated with long-term recurrent vascular events after ischaemic stroke

Ischaemic stroke patients continue to be at risk for recurrent vascular events for many years. Predictors of long-term prognosis are needed. It was the objective of this study to investigate levels of four haemostatic proteins as long-term predictors of recurrent vascular events after ischaemic stroke. We prospectively followed 548 ischaemic stroke patients, 18-69 years, and registered recurrent vascular events. Plasma levels of tissue-type plasminogen activator (t-PA), von Willebrand factor (VWF), fibrinogen and thrombin activatable fibrinolysis inhibitor activation peptide (TAFI-AP) were measured three months after index stroke. Cox regression models were used to assess associations to outcomes for single biomarkers and for a combined biomarker measure. For single biomarkers significantly associated with any of the outcomes, we performed subanalyses stratified for age, sex, diabetes and atherosclerosis. During 5,637 person-years of follow-up, we registered 74 vascular deaths, 90 recurrent strokes and 62 coronary events. Levels of t-PA, VWF and fibrinogen were significantly associated with vascular death and coronary events. After adjustment, the association between t-PA and vascular death remained (HR per 1 SD increase in plasma level 1.27, 95 % CI 1.00-1.61, p=0.047). The combined effect of t-PA, VWF and fibrinogen was associated with coronary events (adjusted HR 1.35, 1.02-1.80, p=0.04). In non-diabetic patients, an association with coronary events was seen for VWF levels (adjusted HR 2.23, 1.45-3.43, p<0.01). In conclusion, plasma levels of haemostatic factors were associated with vascular death and coronary events, but not with recurrent stroke. Our results suggest that the predictive value of biomarkers differ by specific outcome measure and subgroup of patients.

Ischemic Stroke and Six Genetic Variants in CRP, EPHX2, FGA, and NOTCH3 Genes: A Meta-Analysis

BACKGROUND

Ischemic stroke (IS) is a leading cause of death and disability worldwide. As genetic heritability for IS is estimated at about 35%-40%, the identification of genetic variants associated with IS risk is of great importance. The main objective of this study was to carry out a meta-analysis for polymorphisms in CRP, EPHX2, FGA, and NOTCH3 genes and the risk for IS.

METHODS

Literature search for 6 candidate polymorphisms and IS was conducted using HuGE Navigator, PubMed, and Google Scholar databases. Meta-Analyst program was used to calculate pooled odds ratios (ORs) with a random effects model.

RESULTS

Twenty-five published studies for 6 candidate polymorphisms were included: CRP-rs1800947 (5 studies), CRP-rs1205 (3 studies), EPHX2-rs751141 (5 studies), FGA-rs6050 (6 studies), NOTCH3-rs3815188 (3 studies), and NOTCH3-rs1043994 (3 studies), for a total number of 7,825 IS cases and 56,532 control subjects. We did not find significant pooled ORs (P values > .05) for any of the genetic variants evaluated in this work.

CONCLUSIONS

Our meta-analysis results did not show significant associations between these 6 polymorphisms in 4 candidate genes and IS, despite the functional role of some of these single nucleotide polymorphisms (e.g., rs6050 in FGA gene). Future studies are needed to identify additional main genetic risk factors for IS in different populations.

Comparative proteome analysis of blood plasma of patients with early-stage chronic cerebral ischemia

In the present study, we explored the technology of liquid chromatography-mass spectrometry (HPLC-MS/MS) for the proteome analysis of blood plasma of patients with early chronic cerebral ischemia. Analysis of mass-spectrometer data carried out in automatic mode using the software Progenesis LS-MS. As a result of this study identified 43 proteins. The differences identified in the study group compared with the control in 7 proteins. It was found that in the early stages of chronic cerebral ischemia proteome changes in blood plasma affect proteins related to the immune system, the system for the maintenance of hemostasis and lipid metabolism.

Hypercoagulability and the risk of myocardial infarction and ischemic stroke in young women

BACKGROUND

Myocardial infarction (MI) and ischemic stroke (IS) are acute forms of arterial thrombosis and share some, but not all, risk factors, indicating different pathophysiological mechanisms.

OBJECTIVE

This study aims to determine if hypercoagulability has a differential effect on the risk of MI and IS.

PATIENTS AND METHODS

We reviewed the results from the Risk of Arterial Thrombosis in Relation to Oral Contraceptives study, a population-based case-control study involving young women (< 50 years) with MI, non-cardioembolic IS and healthy controls. From these data, relative odds ratios (ORIS /ORMI ) and their corresponding confidence intervals for all prothrombotic factors that were studied in both subgroups were calculated.

RESULTS

Twenty-nine prothrombotic risk factors were identified as measures of hypercoagulability. Twenty-two of these risk factors (21/29, 72%) had a relative odds ratios > 1; for 12 (41%), it was > 2; and for 5 (17%), it was > 2.75. The five risk factors with the largest differences in associations were high levels of activated factor XI (FXI) and FXII, kallikrein, the presence of lupus anticoagulans, and a genetic variation in the FXIII gene.

CONCLUSION

In young women, prothrombotic factors are associated more with the risk of IS than with MI risk, suggesting a different role of hypercoagulability in the mechanism leading to these two diseases.

Fibrinogen alpha and beta gene polymorphisms in pediatric stroke--case-control and family based study

BACKGROUND/PURPOSE

Data on the role of the -455G > A polymorphism of the gene encoding β fibrinogen subunit (FGB) and the Thr312Ala polymorphism of the gene for the α fibrinogen subunit (FGA) in childhood ischemic stroke are insufficient. Therefore the aim of the study was to evaluate a possible association between these two polymorphisms and arterial ischemic stroke.

METHODS

The study group consisted of 85 children after ischemic stroke, 146 of their parents and 159 controls. Both polymorphisms were genotyped using the restriction fragment length polymorphism method. Two study designs were used: a case-control model and a family-based transmission-disequilibrium test. Statistica 7.1 and EpiInfo 6 softwares were used in all analyses.

RESULTS

In the TDT test, a tendency to a higher transmission of the 312Ala allele of the FGA gene and the -455A allele of the FGB gene was observed, however, it was statistically non-significant. The frequencies of alleles and genotypes of both FGA and FGB genes polymorphisms did not differentiate children from both groups also in the case-control model. Additive or synergistic effects between FGA and FGB genes polymorphisms were not observed.

CONCLUSION

An analysis of the results obtained in this study and a critical review of previously published data indicate that examined gene polymorphisms are not related to ischemic stroke in children.

The role of biochemical risk factors in the etiology of AIS in children and adults

Stroke is an abrupt onset of both focal and global neurological deficits secondary to a vascular event lasting more than 24 h and with a vascular background as its only cause. It can be triggered by a rupture of a blood vessel, aneurysm (hemorrhagic stroke, HS), thrombosis or embolisms (ischemic stroke, IS). In developed countries, it is the third most common cause of death in the adult population. Stroke in children is a rare disorder with a reported frequency of about 3 cases per 100,000 children per year. The history of acute brain ischemia is burdened with neurological complications such as motor impairment, speech impairment and intellectual delay. Moreover, in children after AIS seizures and epilepsy are also quite common. Stroke is a heterogeneous disorder; its risk factors in adults are well known, however, in pediatrics, in more than 20% cases, the cause of stroke is impossible to determine. Due to the fact that stroke usually arises as a consequence of the cerebral thrombosis, many of the mechanisms responsible for its occurrence can be considered as risk factors. We have reviewed the recent case-control studies conducted on pediatric patients regarding biochemical risk factors such as elevated levels of homocysteine, fibrinogen, protein C, protein S, antithrombin III, lipoprotein(a), cholesterol and its fractions, and compared them with the results obtained from adult patients.

Association of vWA and TPOX polymorphisms with venous thrombosis in Mexican mestizos

Objective. Venous thromboembolism (VTE) is a multifactorial disorder and, worldwide, the most important cause of morbidity and mortality. Genetic factors play a critical role in its aetiology. Microsatellites are the most important source of human genetic variation having more phenotypic effect than many single nucleotide polymorphisms. Hence, we evaluate a possible relationship between VTE and the genetic variants in von Willebrand factor, human alpha fibrinogen, and human thyroid peroxidase microsatellites to identify possible diagnostic markers. Methods. Genotypes were obtained from 177 patients with VTE and 531 nonrelated individuals using validated genotyping methods. The allelic frequencies were compared; Bayesian methods were used to correct population stratification to avoid spurious associations. Results. The vWA-18, TPOX-9, and TPOX-12 alleles were significantly associated with VTE. Moreover, subjects bearing the combination vWA-18/TPOX-12 loci exhibited doubled risk for VTE (95% CI = 1.02–3.64), whereas the combination vWA-18/TPOX-9 showed an OR = 10 (95% CI = 4.93–21.49). Conclusions. The vWA and TPOX microsatellites are good candidate biomarkers in venous thromboembolism diseases and could help to elucidate their origins. Additionally, these polymorphisms could become useful markers for genetic studies of VTE in the Mexican population; however, further studies should be done owing that this data only show preliminary evidence.

Research on the relationship between fibrinogen level and subtypes of the TOAST criteria in the acute ischemic stroke

Background

Cerebral infarction caused by different reasons seems differ in fibrinogen levels, so the current work intends to explore the relationship between the fibrinogen level and subtypes of the TOAST criteria in the acute stage of ischemic stroke.

Methods

A total of 577 case research objects were treated acute ischemic stroke patients in our hospital from December 2008 to December 2010, and blood samples within 72 hours of the onset were processed with the fibrinogen (PT-der) measurement. Classification of selected patients according to the TOAST Criteria was conducted to study the distribution of fibrinogen levels in the stroke subtypes.

Results

The distribution of fibrinogen levels in the subtypes was observed to be statistically insignificant.

Conclusions

In the acute stage of ischemic stroke, fibrinogen level was not related to the subtypes of the TOAST criteria.

Genetic variation within the interleukin-1 gene cluster and ischemic stroke

BACKGROUND AND PURPOSE

Evidence is emerging that inflammation plays a key role in the pathophysiology of ischemic stroke (IS). The aim of this study was to investigate whether genetic variation in the interleukin-1α, interleukin-1β, and interleukin-1 receptor antagonist genes (IL1A, IL1B, and IL1RN) is associated with IS and/or any etiologic subtype of IS.

METHODS

Twelve tagSNPs were analyzed in the Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS), which comprises 844 patients with IS and 668 control subjects. IS subtypes were defined according to the Trial of Org 10172 in Acute Stroke Treatment criteria in SAHLSIS. The Lund Stroke Register and the Malmö Diet and Cancer study were used as a replication sample for overall IS (in total 3145 patients and 1793 control subjects).

RESULTS

The single nucleotide polymorphism rs380092 in IL1RN showed an association with overall IS in SAHLSIS (OR, 1.21; 95% CI, 1.02-1.43; P=0.03), which was replicated in the Lund Stroke Register and the Malmö Diet and Cancer study sample. An association was also detected in all samples combined (OR, 1.12; 95% CI, 1.04-1.21; P=0.03). Three single nucleotide polymorphisms in IL1RN (including rs380092) were nominally associated with the subtype of cryptogenic stroke in SAHLSIS, but the statistical significance did not remain after correction for multiple testing. Furthermore, increased plasma levels of interleukin-1 receptor antagonist were observed in the subtype of cryptogenic stroke compared with controls.

CONCLUSIONS

This comprehensive study, based on a tagSNP approach and replication, presents support for the role of IL1RN in overall IS.

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.

Fibrinogen and cardiovascular disease: genetics and biomarkers

Several prospective epidemiological studies and clinical observations provided evidence regarding fibrinogen and coronary artery disease (CAD). Many of these studies firmly correlate fibrinogen with CAD. However, it is uncertain whether this relation is causal or reflects genetic variability and residual confounding by other risk factors. Several polymorphisms on fibrinogen chain genes affect its levels, however only few of the genetic variants are associated with increased cardiovascular risk. As regards the role of fibrinogen in myocardial infarction (MI) studies indicate that genetic variations have at best a modest impact on the process resulting in MI. Therefore, the screening of fibrinogen genes might not be useful for the assessment of the risk of MI. However, the findings that specific genotypes lead to specific differences in fibrinogen levels, but may not be linked to cardiovascular risk, complicates the hypothesis of causality of fibrinogen in the pathogenesis of cardiovascular disease.

Plasma levels of von Willebrand factor in the etiologic subtypes of ischemic stroke

BACKGROUND

Compared with coronary artery disease, there are few studies on von Willebrand factor (VWF) in ischemic stroke (IS). Moreover, there is little information on VWF in the etiologic subtypes of IS.

OBJECTIVES

The aim of the present study was to investigate VWF in IS and in the etiologic subtypes of IS.

PATIENTS/METHODS

The Sahlgrenska Academy Study on Ischemic Stroke (SAHLSIS) is a case-control study comprising 600 patients and 600 matched controls. Etiologic IS subtype was defined according to the TOAST criteria. Blood sampling was performed in the acute phase and after 3 months.

RESULTS

The levels of VWF were increased in overall IS, at both time-points. The 3-month VWF levels were increased in the subtypes of large-vessel disease (LVD), cardioembolic (CE) stroke and cryptogenic stroke, but not in the subtype of small-vessel disease (SVD), as compared with the controls. The acute phase VWF levels were significantly increased in all four subtypes. In the multivariate regression analysis, with vascular risk factors as covariates, the 3-month VWF levels were associated with CE stroke and cryptogenic stroke, and the acute phase VWF levels with all subtypes. There were significant subtype-specific differences in VWF, with the highest levels in LVD and CE stroke.

CONCLUSIONS

The present results show that VWF levels are increased in patients with IS. Furthermore, the VWF levels differ between etiologic IS subtypes and thus, it is important to consider etiologic subtypes in future studies of VWF in patients with IS.

Association of genomic loci from a cardiovascular gene SNP array with fibrinogen levels in European Americans and African-Americans from six cohort studies: the Candidate Gene Association Resource (CARe)

Several common genomic loci, involving various immunity- and metabolism-related genes, have been associated with plasma fibrinogen in European Americans (EAs). The genetic determinants of fibrinogen in African Americans (AAs) are poorly characterized. Using a vascular gene-centric array in 23,634 EA and 6657 AA participants from 6 studies comprising the Candidate Gene Association Resource project, we examined the association of 47,539 common and lower frequency variants with fibrinogen concentration. We identified a rare Pro265Leu variant in FGB (rs6054) associated with lower fibrinogen. Common fibrinogen gene single nucleotide polymorphisms (FGB rs1800787 and FGG rs2066861) significantly associated with fibrinogen in EAs were prevalent in AAs and showed consistent associations. Several fibrinogen locus single nucleotide polymorphism associated with lower fibrinogen were exclusive to AAs; these include a newly reported association with FGA rs10050257. For IL6R, IL1RN, and NLRP3 inflammatory gene loci, associations with fibrinogen were concordant between EAs and AAs, but not at other loci (CPS1, PCCB, and SCL22A5-IRF1). The association of FGG rs2066861 with fibrinogen differed according to assay type used to measure fibrinogen. Further characterization of common and lower-frequency genetic variants that contribute to interpopulation differences in fibrinogen phenotype may help refine our understanding of the contribution of hemostasis and inflammation to atherothrombotic risk.

Factor IX and deep vein thrombosis

Elevated levels of several coagulation factors have been found to be associated with an increased risk of thrombosis. In this perspective article, Dr. Lowe examines the implications of the report by Bezemer and coworkers in this issue for our understanding of the mechanisms involved and how they should direct future research.

Fibrinogen alpha and gamma genes and factor VLeiden in children with thromboembolism: results from 2 family-based association studies

Previous case-control studies showed that genetic variation in the fibrinogen gamma gene (FGG) increased the risk for deep vein thrombosis (VT) in adults. We investigated the association between the fibrinogen alpha (FGA) and FGG haplotypes, the factor V(Leiden)-mutation, and pediatric VT and thromboembolic stroke (TS) in 2 independent study samples. Association analysis revealed that the FGA-H1 and FGG-H2 haplotypes were significantly overtransmitted to VT patients (FGA-H1, P = .05; FGG: H2, P = .032). In contrast, the FGG-H3 haplotype was undertransmitted (P = .022). In an independent study sample, FGA-H1 (P = .008) and FGG-H2 (P = .05) were significantly associated with TS. The association of FGA and FGG haplotypes with VT was more pronounced in FV(Leiden)-negative families (FGA-H1, P = .001; FGG-H2, P = .001), indicating a genetic interaction between both risk factors. The risk-conferring FGG-H2 and the protective FGG-H3 haplotypes correlated with low (FGG-H2) and high (FGG-H3) levels of the gamma' chain variant, respectively. These results provide independent and novel evidence that FGA-H1 and FGG-H2 variants are associated with an increased risk of VT and TS in children. The observed negative correlation of genetic VT risk with the plasma levels of the fibrinogen gamma' variant suggests that FGG-H2 and -H3 haplotypes modify thrombosis risk by controlling the level of this FGG splice isoform.

Genetic variation in fibrinogen; its relationship to fibrinogen levels and the risk of myocardial infarction and ischemic stroke

BACKGROUND

Confounding by common causes and reverse causation have been proposed as explanations for the association between high fibrinogen levels and cardiovascular disease. Genetic variants can alter fibrinogen characteristics and are not subject to these problems.

OBJECTIVES

To determine the fibrinogen plasma levels for genotypic variants in fibrinogen-A alpha (FGA Thr312Ala) and fibrinogen-B beta (FGB - 455G/A), and whether these variants are associated with arterial thrombosis.

METHODS

Fibrinogen genotypes were determined in a population-based case-control study including women aged 18-50 years; 218 cases with myocardial infarction, 192 cases with ischemic stroke, and 769 healthy controls. Fibrinogen levels were determined in the control population.

RESULTS

The FGB - 455G/A variant increased plasma fibrinogen levels, whereas the FGA Thr312Ala variant lowered plasma fibrinogen levels, albeit to a modest extent. The risk of ischemic stroke was altered when the homozygote minor allele was compared with the homozygote major allele. The FGA Thr312Ala single-nucleotide polymorphism (SNP) was associated with a decrease in risk [odds ratio (OR) 0.43; 95% confidence interval (CI) 0.21-0.87], whereas the FGB - 455G/A SNP might have increased the risk (OR 1.76; 95% CI 0.7-4.03). The risk of myocardial infarction was not altered for either SNP (FGA Thr312Ala, OR 0.98, 95% CI 0.40-2.40; FGB - 455G/A, OR 0.98, 95% CI 0.40-2.40).

CONCLUSIONS

With the genetic variations as markers of plasma fibrinogen levels alterations, thereby ruling out confounding and reverse causation, our results suggest that plasma fibrinogen levels could play a more pronounced role as risk factors for ischemic stroke than for myocardial infarction.