A Common 4G Allele in the Promoter of the Plasminogen Activator Inhibitor-1 (PAI-1) Gene as a Risk Factor for Pulmonary Embolism and Arterial Thrombosis in Hereditary Protein S Deficiency

[Indirect molecular genetic predisposition factors to increased thrombosis in sufferers with mechanical lower limb trauma]

THE AIM OF THE STUDY

Was to selectively determine the occurrence frequency of polymorphic alleles in candidate genes of hereditary predisposition to increased thrombosis (T) in persons with mechanical trauma of musculoskeletal system (MS), who died from pulmonary artery thromboembolia (PATE). A total of 48 deaths from PATE cases of sufferers with MS trauma. The character of single nucleotide polymorphisms carriage (SNPC) in 13 candidate genes of hereditary predisposition to increased T (in genes, responsible for the synthesis of plasma proteins of the hemostatic system, platelet factors affecting tension of vessel wall and folate cycle) was determined. It has been established that the most common «mutant» alleles are found in PAI-1 -675 5G/4G, MTHFR 677 CT and MTRR 66AG genes, and in 87.8, 53.85 and 75.0% of the analysed cases, respectively. The consideration of SNP carriage character in the genes of predisposition to increased T is required for the full expert judgement on the causality between a mechanical trauma and PATE.

Clinical impact of the PAI-1 4G/5G polymorphism in Chinese patients with venous thromboembolism

Background

Venous thromboembolism (VTE) is a life-threatening cardiovascular syndrome that characterized by the imbalance of hemostasis and thrombosis and the formation of thrombi in the blood vessels. The aim of this study was to elucidate the clinical impact of the PAI-1 4G/5G polymorphism in Chinese patients with VTE.

Methods

A total of 169 subjects (89 VTE, 10 hyperbilirubinemia, 10 hyperlipidemia and 60 healthy controls) were recruited at Peking Union Medical College Hospital. The accuracy of the TaqMan-MGB RT-PCR method for detecting F5 G1691A (FVL) and PAI-1 4G/5G polymorphisms was evaluated by using sequencing method as the gold standard. Besides, the association of the PAI-1 4G/5G polymorphism with susceptibility, treatment efficacy and recurrence status of VTE in Chinese population were explored. Eventually, the plasma PAI-1 antigen levels and PAI-1 4G/5G polymorphisms were determined on additional 64 subjects (32 VTE and 32 healthy controls) simultaneously.

Results

The TaqMan-MGB RT-PCR method was proven to be highly accurate in determining the FVL and PAI-1 4G/5G polymorphisms without interference from bilirubin and lipids in the samples. No obvious correlation of the PAI-1 4G/5G polymorphism with VTE was observed in our study by using five genetic models (allele, genotype, dominant, recessive and additive). Additionally, we also observed that individuals with the 4G/5G genotype had lower neutrophil counts and neutrophil-to-lymphocyte ratio (NLR) than the 5G/5G genotype. Furthermore, we found that the patients with the 5G/5G genotype were more likely to achieve complete recanalization compared to the 4G/4G genotype. In addition, individuals carrying the 5G/5G genotype were more likely to develop a recurrence-free status as compared to individuals with the 4G/4G or 4G/5G genotypes. PAI-1 antigen levels in the VTE group were significantly higher than those in the HC group. However, there was no significant difference in the antigen levels of PAI-1 among subjects carrying various genotypes in the VTE group or HC group.

Conclusion

The PAI-1 4G/5G polymorphism has potential value in assessing the prognosis of Chinese patients with VTE. Our study has laid the foundation for the application of PAI-1 4G/5G polymorphism in the personalized management and monitoring of patients with VTE.

Plasminogen Activator Inhibitor-1 4G/5G Promoter Polymorphism in Adults with Splanchnic Vein Thrombosis: A Case-Control Study

The role of PAI-1 4G/5G polymorphism in venous thrombosis is unclear. PAI-1 4G/4G genotype is associated with elevated levels of PAI-1 resulting in a hypofibrinolytic state and hence increased thrombotic risk. In this study, we assessed the role of PAI-1 4G/5G promoter polymorphism in adult patients with splanchnic vein thrombosis. A total of 40 cases (portal vein thrombosis and Budd-Chiari syndrome) and 40 healthy controls were evaluated for the PAI-1 4G/5G polymorphism by amplification refractory mutation system polymerase chain reaction along with thrombophilia workup. The frequency of PAI-1 4G/4G homozygous, 4G/5G heterozygous and 5G/5G homozygous genotypes were 17.5%, 42.5% and 40%, respectively among cases and 22.5%, 50% and 27.5%, respectively among controls and the difference was not statistically significant (p = 0.61). The  PAI-1 4G/4G genotype was significantly associated with the cases with deranged thrombophilic risk factor (both inherited and acquired) (p = 0.02).

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s12288-021-01454-5.

Genotype Variations and Association between PAI-1 Promoter Region (4G/5G and -844G/A) and Susceptibility to Acute Myocardial Infarction and Chronic Stable Angina

The present study aimed at investigating the 4G/5G and -844G/A polymorphisms and plasma concentration of PAI-1 in patients with acute myocardial infarction (AMI) and chronic stable angina (CSA) in Indian population. It included 100 patients with AMI and stable angina and 100 healthy controls. All study subjects were typed for two PAI polymorphisms (4G/5G and -844G/A) through PCR-RFLP and level of PAI through ELISA. The comparison of AMI and CSA independently with control in terms of PAI-1 level was statistically significant but not between AMI and CSA. The frequency of 4G/4G and 4G/5G genotype and 4G allele was significantly higher in AMI cases than in control and was found to increase the risk of AMI. There was a significant relationship between 4G/5G polymorphism and AMI risk under the dominant and codominant genotype. The frequency of 4G/4G genotype and 4G allele was significantly higher in CSA cases than in control group and increases the risk of CSA. There was no significant association between 4G/5G polymorphism and CSA risk under recessive, dominant, and codominant models. The genotype and allelic frequencies difference between the cases (AMI and CSA) and control with regard to -844G/A polymorphisms were statistically nonsignificant. Also, we did not detect any significant association of -844G/A polymorphism with AMI and CSA in recessive, dominant, and codominant models. Along with the traditional risk factors, the 4G/5G allele polymorphism is an independent risk factor for the development of AMI. The detection of 4G/5G allele may therefore be helpful in primary prevention. Patients who carry the 4G/5G allele polymorphism have high concentrations of PAI-1, which might be involved in incidents leading to AMI. The present study for the first time revealed significant association of 4G/5G allele polymorphism with high risk of AMI in Indian population and will be helpful in identifying the genetic risk factors associated with AMI and CSA and for better management of diagnostic measures.

Deep vein thrombosis and recurrent pulmonary embolism in a patient with thrombophilic mutations and generalized psoriasis: A case report

Abstract: Introduction: Genetic risk factors that increase venous thromboembolism risk are disorders in the synthesis or activity of coagulation factors. Factor V Leiden, prothrombin (20210-A), antithrombin deficiency, protein C and protein S deficiency, and hyperhomocysteinemia are the most common venous thromboembolism-related gene mutations. When genetic factors are combined with non-provoking risk factors (obesity, psoriasis, smoking and previous venous thromboembolism) the result is increased venous thromboembolism risk for each factor individually. Previous venous thromboembolism is one of the strongest risk factors, even in patients actively treated with anticoagulants. Patients are more likely to have recurrent venous thromboembolism with longer duration. Psoriasis is a complex immune-mediated disease, associated with cardiovascular risk, hypercoagulability markers and elevated homocysteine. Lots of observational reports suggest increased incidence of venous thromboembolic events in patient with psoriasis. Case presentation: We present patient with inherited thrombophilia and chronic diffuse plaque psoriasis complicated with deep venous thrombosis and pulmonary embolism. DNA analysis indicates the presence of homozygosis for Factor V Leiden mutation as well as heterozygosis for Factor XIII V34L, PAI-1 5G/4G and MTHFR A1298C polymorphism. Dermatological anamnesis is positive for plaque psoriasis since 12 years ago. Conclusion: The presentation of this case indicates an association between venous thromboembolism and chronic psoriasis. All patients with recurrent thromboembolism, hereditary thrombophilia, and moderate to severe psoriasis should be considered to be at higher risk for venous thromboembolism and appropriately treated.

Investigation of Plasminogen Activator Inhibitor-1 (PAI-1) 4G/5G promoter polymorphism in Indian venous thrombosis patients: A case-control study

BACKGROUND

The role of PAI-1 4G/5G polymorphism in venous thrombosis has been contradictory. PAI-1 4G/4G genotype is associated with elevated levels of PAI-1 resulting in a hypofibrinolytic state and a higher thrombotic risk.

OBJECTIVE

In this study, the distribution of genotypes and frequency of alleles of the 4G/5G polymorphism of PAI-1 gene in Indian patients with different types of venous thrombosis was investigated for its role in development of thrombosis.

METHOD

A total of 87 portal vein thrombosis (PVT), 71 Budd-Chiari syndrome (BCS), 156 cerebral vein thrombosis (CVT), and 163 deep vein thrombosis (DVT) patients were studied alongside 251 healthy controls for the PAI-1 4G/5G polymorphism by allele-specific PCR.

RESULTS

Frequency of 4G/4G genotype was higher in all groups in comparison with controls. 4G/4G was associated with PVT risk (OR=2.51, 95% CI=1.29-4.96, P=.0075), BCS risk (OR=5.98, 95% CI=2.68-13.42, P<.0001), and DVT risk (OR=1.75, 95% CI=0.98-3.02, P=.0225). This is the first case-control study from India establishing PAI-1 4G/4G as a strong risk factor for abdominal thrombosis (PVT and BCS). Statistically significant association was not found between 4G/4G genotype and CVT risk.

CONCLUSION

PAI-1 4G/4G is a strong risk factor for venous thrombosis in Indian patients and should be included in laboratory testing panel of thrombophilia.

Soluble urokinase plasminogen activator receptor and incidence of venous thromboembolism

Raised plasma levels of the soluble urokinase plasminogen activator receptor (suPAR) have been associated with increased incidence of cardiovascular diseases. Whether suPAR is associated with venous thromboembolism (VTE) is largely unknown. The purpose of the present study was to investigate the relationship between suPAR and incidence of VTE in a cohort study. suPAR was measured in 5,203 subjects (aged 46-68 years, 58 % women) from the general population, who participated in the Malmö Diet and Cancer (MDC) study between 1991 and 1994. Incident cases of VTE were identified from the Swedish patient register during a mean follow-up of 15.7 years. Of 5,203 subjects with measurements of suPAR, 239 had VTE during follow-up (127 venous thrombosis, 86 lung embolism, 26 both). Incidence of VTE was significantly higher in subjects with suPAR levels in the top quartile. Adjusted for age and sex, the HR (4th vs 1st quartile) was 1.74 (95 %CI: 1.2-2.6, p for trend=0.003). After adjustments for risk factors, the HR was 1.66 (95 %CI: 1.1-2.5, p for trend=0.016). High level of suPAR was a risk indicator for incidence of VTE in this population-based cohort study. The causal relationships between suPAR and VTE remain to be explored.

Plasminogen activator inhibitor-1 4G/5G polymorphism, factor V Leiden, prothrombin mutations and the risk of VTE recurrence

Plasminogen-activator inhibitor (PAI)-1 is an important inhibitor of the plasminogen/plasmin system. PAI-1 levels are influenced by the 4G/5G polymorphism in the PAI-1 promoter. We investigated the relationship between the PAI-1 polymorphism and VTE recurrence, and its possible modification by factor V Leiden (FVL) and prothrombin (PTM) mutations. Patients (n=1,069) from the Malmö Thrombophilia Study were followed from discontinuation of anticoagulant treatment until diagnosis of VTE recurrence or the end of the study (maximum follow-up 9.8 years). One hundred twenty-seven patients (11.9 %) had VTE recurrence. PAI-1 was genotyped by TaqMan PCR. Cox regression analysis adjusted for age, sex and acquired risk factors of VTE showed no evidence of an association between PAI-1 genotype and risk of VTE recurrence in the study population as a whole. However, by including an interaction term in the analysis we showed that FVL but not PTM modified the effect of PAI-1 genotype: patients with the 4G allele plus FVL had a higher risk of VTE recurrence [hazard ratio (HR) =2.3, 95 % confidence interval (CI) =1.5-3.3] compared to patients with the 4G allele but no FVL (reference group) or FVL irrespective of PAI-1 genotype (HR=1.8, 95 % CI=1.3-2.5). Compared to reference group, 5G allele irrespective of FVL was associated with lower risk of VTE recurrence only when compared with 4G allele together with FVL. In conclusion, FVL has a modifying effect on PAI-1 polymorphism in relation to risk of VTE recurrence. The role of PAI-1 polymorphism as a risk factor of recurrent VTE may be FVL dependent.

Analysis of the protein-protein interaction networks of differentially expressed genes in pulmonary embolism

The aim of the present study was to explore the function and interaction of differentially expressed genes (DEGs) in pulmonary embolism (PE). The gene expression profile GSE13535, was downloaded from the Gene Expression Omnibus database. The DEGs 2 and 18 h post-PE initiation were identified using the affy package in R software. The Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways of the DEGs were analyzed using Database for Annotation Visualization and Integrated Discovery (DAVID) online analytical tools. In addition, protein-protein interaction (PPI) networks of the DEGs were constructed using the Search Tool for the Retrieval of Interacting Genes/Proteins. The PPI network at 18 h was modularized using ClusterONE, and a functional enrichment analysis of the DEGs in the top three modules was performed with DAVID. Overall, 80 and 346 DEGs were identified 2 and 18 h after PE initiation, respectively. The KEGG pathways, including chemokine signaling and toll-like receptor signaling, were shown to be significantly enriched. The five highest degree nodes in the PPI networks at 2 or 18 h were screened. The module analysis of the PPI network at 18 h revealed 11 hub nodes. A Gene Ontology terms analysis demonstrated that the DEGs in the top three modules were associated with the inflammatory, defense and immune responses. The results of the present study suggest that the DEGs identified, including chemokine-related genes TFPI2 and TNF, may be potential target genes for the treatment of PE. The chemokine signaling pathway, inflammatory response and immune response were explored, and it may be suggested that these pathways have important roles in PE.

Natural and engineered plasmin inhibitors: applications and design strategies

The serine protease plasmin is ubiquitously expressed throughout the human body in the form of the zymogen plasminogen. Conversion to active plasmin occurs through enzymatic cleavage by plasminogen activators. The plasminogen activator/plasmin system has a well-established function in the removal of intravascular fibrin deposition through fibrinolysis and the inhibition of plasmin activity; this has found widespread clinical use in reducing perioperative bleeding. Increasing evidence also suggests diverse, although currently less defined, roles for plasmin in a number of physiological and pathological processes relating to extracellular matrix degradation, cell migration and tissue remodelling. In particular, dysregulation of plasmin has been linked to cancer invasion/metastasis and various chronic inflammatory conditions; this has prompted efforts to develop inhibitors of this protease. Although a number of plasmin inhibitors exist, they commonly suffer from poor potency and/or specificity of inhibition that either results in reduced efficacy or prevents clinical use. Consequently, there is a need for further development of high-affinity plasmin inhibitors that maintain selectivity over other serine proteases. This review summarises clearly defined and potential applications for plasmin inhibition. The properties of naturally occurring and engineered plasmin inhibitors are discussed in the context of current knowledge regarding plasmin structure, specificity and function. This includes design strategies to obtain the potency and specificity of inhibition in addition to controlled temporal and spatial distribution tailored for the intended use.

Free protein S level as a risk factor for coronary heart disease and stroke in a prospective cohort study of healthy United Kingdom men

Plasma protein S (PS) levels are reportedly low in patients with venous thrombosis but high in coronary heart disease (CHD) patients. The authors examined the association between free PS concentration and CHD or stroke risk and assessed risk in combination with C-reactive protein (CRP) levels. Free PS concentration was determined in 6 annual visits among 3,052 middle-aged (49-64 years) United Kingdom men from the Second Northwick Park Heart Study, with 297 CHD events from 1989 to 2005. The highest (vs. first) quintile was associated with a significantly increased CHD risk after adjustment for all other risk factors and correction for regression dilution bias (hazard ratio = 1.85, 95% confidence interval: 1.08, 3.16; P = 0.024). Models that included all well-known risk factors plus PS quintiles improved prediction of CHD (net reclassification improvement (NRI) = 7.0% (P = 0.007), category-less NRI (>0) = 22.1% (P < 0.001)), and the likelihood ratio statistic increased significantly (P = 0.018). The increase in CHD risk was particularly strong when subjects also had high CRP levels. There was no association between free PS level and stroke risk. This study confirms the independent association of elevated free PS levels with future risk of CHD, although elevated PS levels added only modestly to prediction metrics. The novel finding of increased CHD risk, particularly when CRP and PS levels are high, requires further study.

Failure to lyse venous thrombi because of elevated plasminogen activator Inhibitor 1 (PAI-1) and 4G polymorphism of its promotor genome (The PAI-1/4G Syndrome)

Plasminogen activator Inhibitor 1 (PAI-1) inhibits plasminogen activators leading to decreased fibrinolysis and increased risk of thromboembolic disease (TED). Shifts in PAI-1 promoter genome from normal 5G>5G to 4G>5G or 4G>4G alleles are associated with overexpression of PAI-1. In this study patients with residual venous thrombi were observed to have increased PAI-1 levels and more frequent shifts to 4G alleles. Of the 26, 20 (76.9%) patients with unresolved thrombus had elevated PAI-1 values. 4G genomic shifts were found in 92.9% patients studied. Normal PAI-1 levels were found in 5 patients with 4G polymorphisms. Thus, PAI-1 is often elevated among patients with residual thrombus, with an unexpectedly high prevalence of the 4G polymorphism of the promoter genome. Patients with persistent thrombus should be considered at risk of having constituently increased PAI-1 due to genomic changes in the PAI-1 promoter genome. Hypotheses are proposed to explain those with normal PAI-1, despite having 4G polymorphisms.

Genetic Mutations in Turkish Population With Pulmonary Embolism and Deep Venous Thrombosis

Venous thromboembolism (VTE) is a universal health hazard. Inherited and acquired risk factors increase the risk of VTE. We evaluated the relationship between factor V (G1691A, A1090G, and A1299G), prothrombin (PT G20210A), methylenetetrahydrofolate reductase (MTHFR C677T) mutations, plasminogen activator inhibitor 1 (PAI-1 -675) polymorphism, and VTE in Turkish population. In all, 80 patients with VTE and 104 controls were included. Heterozygous factor V Leiden (FVL) mutation was significantly higher among patients ( P = .04) with allele frequency of 6.3% ( P = .01). Heterozygous PT G20210A mutation was also significantly higher among patients ( P = .001) with allele frequency of 6.9% ( P = .003). MTHFR 677TT genotype was significantly higher in patients ( P = .009) with allele frequency of 23.8% ( P = .005). No significant difference was found in FV A1090G and FV A1299G mutation rate as well as PAI-1 genotypes and their allele frequencies ( P > .05). Thus, frequencies of FV G1691A, PT G20210A, and MTHFR C677T mutations are higher in patients with VTE. FV A1090G, FV A1299G mutations, and PAI-1 gene polymorphisms may not be a risk factor for VTE in Turkish population.

Thrombophilic dimension of recurrent fetal loss in Indian patients

We studied the prevalence of acquired and genetic thrombophilia in 198 women with recurrent fetal loss who were having three or more than three abortions. Seventy-nine women had only early pregnancy losses, that is, first trimester abortions, 30 women had only late pregnancy losses, that is, second and third trimester abortions whereas 89 had both early and late pregnancy losses. The control group included 100 age-matched fertile parous women who did not have any obstetric complications and had at least one normal healthy child. Several genetic and acquired thrombophilia markers were studied. The strongest association was observed with anticardiolipin (odds ratio 22.6, confidence interval 5.7-89, P = 0) followed by lupus anticoagulant, anti-beta2 glycoprotein-1, antiannexin. Association of antiphospholipid antibody syndromes was detected with the time of pregnancy loss in anticardiolipin, lupus anticoagulants, which was significantly associated with early pregnancy loss as compared with second and third trimester loss. In case of beta2 glycoprotein-1, antiannexin it was less significantly associated with early pregnancy loss as compared with second and third trimester loss. The risk of fetal loss with protein S deficiency was the highest risk observed for any heritable thrombophilia, followed by protein C, factor V Leiden, endothelial protein C receptor, antithrombin III deficiency and beta448 fibrinogen polymorphism. Modest risks were also observed with 5,10-methylenetetrahydrofolate reductase, plasminogen activator inhibitor 4G/4G polymorphisms and beta448 fibrinogen polymorphism. A combination of two or more than two genetic risk factors were observed in 55 (27.7%), whereas the genetic and acquired risk factors were observed in 107 (54%) of the cases. Thrombophilia is an important contributing factor for both early and late pregnancy losses; approximately two-thirds of our cases of unexplained fetal losses could be explained by acquired or heritable thrombophilia or both, which is in line with other western studies.

Mechanisms of Venous Thrombosis and Resolution

Venous thromboembolism is a significant health care problem in the US. In this review, the unique role of inflammation to the venous thrombotic process is emphasized as well as the potential role of abnormalities of fibrinolytic mechanisms to the thrombotic process. Inflammation influences not only thrombogenesis but also thrombus resolution and vein wall remodeling, and these interactions are also discussed. Knowledge of molecular and immunologic mechanisms for venous thrombosis and its resolution should allow for the future development of targeted therapies.

The role of plasminogen activator inhibitor-1 polymorphism, factor-V-Leiden, and prothrombin-20210 mutations in pulmonary thromboembolism

Polymorphism in plasminogen activator inhibitor-1 gene is suggested to be associated with an increased risk of venous thromboembolism. The aim of this study was to investigate the association of plasminogen activator inhibitor-1 gene polymorphism and its coexistence with factor-V-Leiden and prothrombin-20210 mutations in pulmonary thromboembolism. The authors investigated plasminogen activator inhibitor-1 4G/5G polymorphism, factor-V-Leiden, and prothrombin-20210 mutations in 143 pulmonary thromboembolism patients and 181 controls. Plasminogen activator inhibitor-1 4G/4G, 4G/5G, and 5G/5G gene polymorphisms and prothrombin-20210 mutations were not different between cases and controls. Factor-V-Leiden mutation was present in 21.0% and 7.7% of the cases and controls, respectively, P = .001. Neither different plasminogen activator inhibitor-1 genotypes and 4G allele nor coexistence of the allele with factor-V-Leiden or prothrombin-20210 was associated with the risk of recurrence. As a result, plasminogen activator inhibitor-1 gene polymorphism or its concomitant presence with mentioned mutations was not found to be associated with increased risk for pulmonary thromboembolism or recurrent disease in this study.

The PAI-1 gene 4G/5G polymorphism and deep vein thrombosis in patients with inherited thrombophilia

Genetic and acquired factors may influence phenotypic expression of inherited thrombophilia. Hypofibrinolysis due to excess PAI-1 can be found in patients with deep vein thrombosis (DVT) and 4G/5G polymorphism of the PAI-1 gene may modulate the inhibitor's synthesis. In 149 patients with inherited thrombophilia, the possible thrombotic contribution of both 4G/5G polymorphism and PAI-1 plasma levels was evaluated. Sixty-seven patients with idiopathic DVT and 98 normal subjects were also studied. By comparison with controls, a significantly higher prevalence of 4G/4G genotype was seen in idiopathic DVT and in thrombophilia patients, although in this latter group the difference only remained significant in cases symptomatic for thrombosis (p = 0.01). The 4G/4G genotype was associated with a greater risk of thrombosis both in symptomatic thrombophilia patients (OR 2.85, 95% CI 1.26-6.46) and in idiopathic DVT patients (OR 3.1, 95% CI 1.26-7.59). The greater frequency of 4G allele in symptomatic thrombophilia patients with respect to controls was statistically significant (p = 0.04). Compared to healthy subjects, PAI-1:Ag levels were higher in symptomatic thrombophilia patients and related to the 4G/5G polymorphism, with significantly higher values in the 4G/4G carriers. In conclusion, PAI-1 4G/5G polymorphism may influence PAI-1 expression and thrombotic risk in patients with inherited thrombophilia.

Prospective study of fibrinolytic markers and venous thromboembolism

Prior research has conflicted on whether increased levels of plasma fibrinolytic factors may identify patients at risk of venous thromboembolism (VTE). We therefore performed a nested case-control study of VTE within two prospective population-based studies. In 308 participants who developed VTE and 640 controls, we measured PAI-1 antigen, tPA/PAI-1 complex, plasmin-alpha 2-antiplasmin (PAP), and the PAI-1 -675 4G/5G promoter polymorphism on pre-event blood samples. There was no overall association between any of these fibrinolytic variables and VTE, after adjustment for age or for multiple VTE risk factors. There was weak evidence for an interaction of PAP with elevated factor VIIIc and elevated D-dimer in augmenting VTE risk. We conclude that, for the most part, these fibrinolytic markers do not identify healthy subjects at risk for VTE.

Factor V Leiden mutation and PAI-1 gene 4G/5G genotype in thrombotic patients with Behcet's disease

Behcet's disease is a chronic systemic vasculitis with particular systemic features including thrombotic events. The present study was designed to analyse the role of the factor V Leiden and the prothrombin G20210A mutations and plasminogen activator inhibitor-1 4G/5G polymorphism on the thrombotic risk of patients with Behcet's disease. A total of 50 unrelated patients with Behcet's disease (34 male, 16 female) were the subjects of the study. Twenty-seven of 50 patients with a history of thrombosis comprised group 1, and 23 patients with no thrombosis comprised group 2. In group 1, nine of the 27 patients (33%) were found to have the factor V Leiden mutation (7.1% in healthy population), and the 4G/4G genotype was found in 23% of the patients (26% in control). No patient had the prothrombin G20210A mutation (2.2% in healthy control). In group 2, two patients (9%) had the factor V Leiden and one patient (4%) had the prothrombin G20210A mutations. The 4G/4G polymorphism was found in 30.5% of the patients. The differences in the frequencies of factor V Leiden mutation between group 1 and group 2 (odds ratio, 5.3; 95% confidence interval, 1.0-27.5) and between group 1 and the healthy population were statistically significant ( 0.05). No statistically significant association was found for the prothrombin G20210A mutation and the 4G/5G genotype between the two groups or between each group and the healthy population, indicating that the prothrombin G20210A mutation and the 4G/4G polymorphism do not play a role in the development of thrombosis in Behcet's disease. These data suggested that the factor V Leiden mutation might be a risk factor for the development of thrombosis in Behcet's disease patients.

Hereditary and acquired defects in the fibrinolytic system associated with thrombosis

The fibrinolytic system plays a pivotal role in the regulation of hemostasis and the prevention of thrombosis. There are no drugs that will increase the plasma fibrinolytic activity for a lasting duration to prevent thrombotic events effectively. Despite the ability of vasoactive agents such as nicotinic acid and metformin to release PA from the vessel wall, this therapeutic effect has not been evaluated adequately. The PAs are short-acting and indicated only for thrombolysis and not for prophylaxis. Future directions are directed at finding, agents that can enhance plasminogen activator release or inhibit PAW-1 activity. As there are multiple factors involved in the pathogenesis of thrombosis, there are a number of conditions in which abnormal fibrinolysis is only a contributory factor. Examples are seen in pregnancy, especially during puerperium, when the thromboembolic risk is at its highest. The levels of inhibitors of fibrinolysis. both PAI-1 and PAI-2, are also at their highest. Another example was seen recently in the antiphospholipid syndrome, where antibodies against Annexin II, a receptor for tPA, were found to be higher than in healthy controls. Thus, a thorough investigation into other hereditary and acquired risk factors for thrombosis is recommended.

Plasminogen activator inhibitor-1 levels and polymorphisms

OBJECTIVE

To review the published evidence of a relationship between levels of plasminogen activator inhibitor-1 (PAI-1) or the 4G/5G polymorphism of the PAI-1 gene and the occurrence of venous thromboembolic disease.

METHODS

Review of the medical literature using computerized databases and a review of secondary sources identified through bibliographies.

DATA SYNTHESIS

Plasminogen activator inhibitor-1 is an important inhibitor of the fibrinolytic system, so it is biologically plausible that elevated levels could suppress fibrinolysis and result in an increased risk of thrombosis. Several small studies reported associations between PAI-1 levels and venous thromboembolism, some of which appear to be familial. Problems with these studies include variations in PAI-1 plasma levels due to circadian changes and the acute phase response, as well as alterations due to common comorbid disease states. More recent investigations have focused on genetic polymorphisms, particularly the 4G/5G insertion/deletion in the promoter region, affecting transcription rates. The relation of 4G/5G to venous thrombosis has been investigated primarily in case-control studies, which have produced inconsistent findings. Most studies, however, have reported higher PAI-1 plasma levels in individuals with 4G/4G.

CONCLUSIONS

The evidence regarding the relationship between an elevated PAI-1 plasma level or PAI-1 genetic polymorphism and the risk of venous thromboembolism is conflicting. There is insufficient information to recommend use of PAI-1 levels or genotype in evaluating thrombophilia.

PAI-1 gene 4G/5G genotype: A risk factor for thrombosis in vessels of internal organs

Although the common 4G/5G polymorphism in the promoter of the PAI-1 gene was suggested to be a risk factor for some of the thrombotic disorders, its significance in the development of thrombosis is still controversial. This study presents the data on a total of 357 patients with different types of thrombosis and 281 unrelated healthy controls. It was found that the 4G/4G genotype is associated with a higher risk of thrombosis (OR, 1.7; 95% CI, 1.1-2.5). Patients were divided into five distinct groups according to the site of thrombosis. Both 4G/4G and 4G/5G genotypes were associated with a higher risk of thrombosis development in a group of 69 patients with internal organ thrombosis (OR, 6.35; 95% CI, 2.5-16.1 and OR, 4.85; 95% CI, 2.0-12.1, respectively). Interestingly, this association was even stronger in a subgroup of 33 patients with portal vein thrombosis (PVT) and 4G/4G and 4G/5G genotypes conferred more than 10- and 6-fold increases in the risk of developing PVT (95% CI: 2.3-47.1 and 1.4-28.8), respectively. No statistically significant association was found between 4G/4G genotype and the groups of deep vein thrombosis (126 patients), cerebral thrombosis (80 patients), retinal thrombosis (72 patients), and purpura fulminans (16 patients). Factor V Leiden or prothrombin G20210A mutations did not emerge as additional risk factors for thrombosis in any of the groups studied. To conclude, this study suggests that there may be an association between 4G/4G and 4G/5G genotypes and the thrombosis in vessels of internal organs especially in the portal veins.

Inherited thrombophilia and stillbirth

Thrombophilias are inherited or acquired conditions that predispose individuals to thromboembolism. New inherited thrombophilias are recognized each year. Some, but not all, studies have found an association between inherited thrombophilias and adverse pregnancy outcomes, including fetal loss. The controversy regarding the clinical implications of thrombophilias in pregnancy is clouded by differences in study populations, the number of thrombophilias tested, interactions between thrombophilias, and the retrospective nature of most studies, just to name a few factors. The lack of adequately designed studies also extends to clinical management. Clear evidence to determine when to test, whom to test, which thrombophilias to test for, when to treat, and what to treat with is not available. Further studies to investigate these questions are urgently needed.

Factor V Leiden: a genetic risk factor for thrombotic microangiopathy in patients with normal von Willebrand factor-cleaving protease activity

Thrombotic microangiopathy (TM) is associated with abnormalities of von Willebrand factor-cleaving protease (VWCP) and other hemostatic factors. This study hypothesized that TM patients might have genetically determined thrombotic risk factors that predispose them to aberrant microvascular thrombosis. DNA samples from 30 white and 12 African American adult TM patients were analyzed for genetic alleles associated with vascular thrombosis, and plasma samples were analyzed for levels of VWCP activity. DNA was analyzed by using allele-specific polymerase chain reaction for factor V 1691A (Leiden), factor II 20 210A, methylenetetrahydrofolate reductase 667T, type 1 plasminogen activator inhibitor 4G/5G, and platelet GPIa 807T. Patients were segregated by race (white or African American) and plasma level of VWCP activity (normal or deficient). The prevalence of factor V Leiden was significantly increased among the white TM patients that had normal VWCP activity: 4 (36%) of 11 patients compared with 6 (3%) of 186 white control subjects possessed the factor V Leiden allele (P <.001; odds ratio, 17.1; 95% confidence interval, 5.4-54.0). No factor V Leiden alleles were detected in 19 white TM patients with intermediate or deficient levels of VWCP activity or in any of 12 African American patients. The prevalence of other thrombosis-associated alleles did not differ between TM patients and control subjects. These findings suggest that factor V Leiden may be a pathogenic risk factor in TM patients that have normal VWCP activity.

Plasminogen activator inhibitor type-1 in cardiovascular disease. Status report 2001

Plasminogen activator inhibitor type-1 (PAI-1) is known to contribute to thrombus formation and to the development and the clinical course of acute and chronic cardiovascular disease, as well as of other arterial and venous thromboembolic diseases. Recently, an important role of elevated pretreatment levels of PAI-1 for failure of thrombolytic therapy of acute myocardial infarction has been discussed. PAI-1 plasma levels depend on the one hand on gene regulation but are related on the other hand to known risk factors of atherosclerosis like insulin resistance, diabetes or hypertriglyceridemia, respectively. Furthermore, an activated renin-angiotensin-aldosterone system (RAAS) significantly contributes to the upregulation of PAI-1 concentration via a receptor-mediated mechanism. In accordance to the known mechanisms of regulation of PAI-1 plasma levels, the use of specific agents like antidiabetic drugs, fibrates, statins, ACE inhibitors and angiotensin II type-1 receptor-blockers may contribute to the downregulation of circulating PAI-1 and, therefore, increase the fibrinolytic capacity and consecutively counteract the thrombotic tendency. To further improve the efficacy of thrombolytic therapy, a PAI-1 resistant variant of t-PA, TNK-t-PA, has been developed and is now available for acute myocardial infarction.

Complementary effects of Mediterranean diet and moderate red wine intake on haemostatic cardiovascular risk factors

OBJECTIVES

To compare the effect of alcohol-free Mediterranean-type diet (MD) and high-fat diet (HFD) on plasma concentration of emergent haemostatic cardiovascular risk factors (HCVRF). Also, to test if red wine supplementation modifies HCVRF, independent of diet.

DESIGN, SUBJECTS AND INTERVENTION

Controlled prospective intervention study. Two groups, each of 21 healthy male university students (22+/-3.4 y), received either MD or HFD for 90 days. Between days 30 and 60, both diets were supplemented with 240 ml/day of red wine. Baseline and T30, T60 and T90-day samples were drawn. No drop out from the study was observed.

SETTING

University campus and outpatient nutrition clinic.

RESULTS

Volunteers on HFD at T30 had increases in pro-coagulants fibrinogen (22%), factor VIIc (9%), and factor VIIIc (4%), and decreases in natural anticoagulants antithrombin III (3%), protein C (11%) and protein S (6%) and of 20% in plasminogen activator inhibitor-1. At the same time, individuals on MD had increases in fibrinogen (4%), antithrombin III (5%), protein C (3%), protein S (2.7%), and decreases in factor VIIIc (9%), and plasminogen activator inhibitor-1 (21%). After adjusting by baseline values, MD was associated with lower plasma fibrinogen (P=0.03), factor VIIc (P=0.034) and factor VIIIc (P=0.0057) and with higher levels of protein S (P=0.013). Red wine supplementation, in both diets, resulted in decreased plasma fibrinogen (P=0.001) and factor VIIc (P=0.05), and increased tissue plasminogen activator antigen (P=0.01) and plasminogen activator inhibitor-1 antigen (P=0.0003). Wine consumption was also associated with significantly (P=0.01) divergent effects on antithrombin III: it decreased by 10% in individuals on HFD but increased slightly in those on MD. No effects of diet or wine were detected in plasma protein C and C-reactive protein.

CONCLUSION

MD and moderate consumption of red wine have complementary, mostly beneficial effects on HCVRF.

An association between plasma free protein s concentration and risk of coronary heart disease in middle-aged men

Protein S is a vitamin K-dependent protein with anticoagulant properties. Case series have reported reduced plasma concentrations in patients with arterial thromboses, while other studies have reported increased levels in patients with coronary heart disease (CHD). The present study sought to clarify the relation between free protein S and risk of CHD. A prospective survey was conducted of 3000 men aged 50 to 61 years, free of clinical CHD at baseline. Free protein S was measured by commercial immunoassay. End-points recorded were sudden coronary death, first nonfatal and fatal myocardial infarction (MI), surgical intervention for symptomatic, angiographically demonstrated CHD, and all-causes mortality. Statistical analysis employed univariate incidence rate ratios followed by Cox proportional hazards regression. There were 168 CHD events recorded during 21,000 person-years of risk. Mean free protein S concentration was 6% higher in those who developed CHD than in the remainder, the crude hazard ratio (HR) for a one standard deviation (S.D.) increase in free protein S being 1.25 (95% CI, 1.08-1.25). Free protein S was associated with cholesterol concentration and other conventional CHD risk factors. In multivariate regression analysis, after adjustment for conventional CHD risk factors a 1 S.D. increase in free protein S was associated with a HR of 1.15 (0.98-1.35) for CHD, of borderline conventional statistical significance. This association of free protein S with risk of CHD may reflect effects of plaque-destabilising inflammatory activity on protein S levels.

Prothrombotic disorders and ischemic stroke in children

Childhood ischemic stroke, including arterial ischemic stroke (AIS) and sinovenous thrombosis (SVT), is relatively rare in children but can result in devastating morbidity and mortality. An understanding of the etiology of childhood stroke is important because strategies for primary and secondary prevention can be devised. Prothrombotic disorders may contribute to the etiology of childhood stroke, and include deficiencies of antithrombin, protein C, protein S, plasminogen, and presence of Factor V Leiden, Prothrombin gene G20210A, dysfibrinogenemia, antiphospholipid antibodies, hyperhomocysteinemia, and elevated lipoprotein (a). The overall incidence of prothrombotic disorders in childhood AIS is estimated to be 20% to 50% in most studies and, in childhood SVT, to be 33% to 99%. In addition, hyperlipidemia, polycythemia, iron deficiency anemia, and platelet disorders may result in a prothrombotic state associated with ischemic stroke. The etiologic contribution of these prothrombotic disorders to initial and recurrent stroke has not been clearly defined; however, additional risk factors are usually present in affected children. Given the prevalence of prothrombotic disorders in childhood stroke, and their likely causative role, children with stroke should be screened for prothrombotic disorders. Future prospective and multicenter studies will elucidate the contribution of specific prothrombotic disorders to initial and recurrent stroke, and optimal therapy.

PAI-1 promoter 4G/5G genotype as an additional risk factor for venous thrombosis in subjects with genetic thrombophilic defects

Impaired fibrinolysis as a result of increased plasminogen activator inhibitor-1 (PAI-1) levels in plasma is a common finding in patients with deep vein thrombosis (DVT). A 4G/5G polymorphism in the promoter region of the PAI-1 gene has been reported to influence the levels of PAI-1. The 4G allele was found to be associated with higher plasma PAI-1 activity (act), but contradictory results on the incidence of the 4G allele in DVT patients have been reported. The aim of this study was to analyse whether the PAI-1 promoter 4G/5G genotype increases the risk of venous thrombosis in subjects with thrombophilic defects, and to determine the distribution of the PAI-1 4G/5G genotype and its relation to plasma PAI-1 levels in 190 unrelated patients with DVT in comparison with a control group of 152 healthy subjects. No differences between the 4G/5G allele distribution in the DVT group (0.43/0.57) and in the control group (0.42/0.58) were observed. However, the presence of the 4G allele significantly increased the risk of thrombosis in patients with other thrombophilic defects. Significantly higher PAI-1 levels were observed in DVT patients than in the controls. Our results also showed significant differences in the plasma levels of PAI-1 antigen (ag) and PAI-1 act among the 4G/5G genotypes in DVT patients. A multivariate analysis revealed that, in the DVT group, PAI-1 ag levels were influenced by the 4G allele dosage, triglyceride levels and body mass index (BMI). The influence of the 4G allele dosage on PAI-1 levels was independent of the triglyceride levels and BMI. In the control group, no significant correlation between PAI-1 levels and 4G allele dosage was observed. In conclusion, the PAI-1 promoter polymorphism was found to have an influence on PAI-1 levels in DVT patients and on the risk of venous thrombosis in subjects with other genetic thrombophilic defects.

The 4G/5G polymorphism of the type 1 plasminogen activator inhibitor gene and thrombosis in patients with antiphospholipid syndrome

OBJECTIVE

To investigate the relationship between the 4G/5G polymorphism of the type 1 plasminogen activator inhibitor (PAI-1) gene and thrombotic manifestations in patients with antiphospholipid syndrome (APS).

METHODS

We studied a total of 247 patients included in the following 4 groups: 70 patients with primary APS, 104 patients with systemic lupus erythematosus (40 with antiphospholipid antibodies [aPL] and clinical [secondary] APS, 13 with aPL but without clinical APS, and 51 with neither detectable aPL nor a history of thrombosis), 14 asymptomatic individuals with aPL, and 59 patients with thrombosis but without known thrombosis risk factors. A control group of 100 healthy individuals was also analyzed. PAI-1 4G/5G polymorphism was determined by polymerase chain reaction and endonuclease digestion.

RESULTS

The allele frequency of 4G/5G in controls was 0.47/0.53. There were no differences in allele distribution among patient groups or between patients and controls. However, a higher frequency of the 4G allele was observed in APS patients with versus those without thrombosis (0.57 versus 0.39; P < 0.05) (odds ratio [OR] 2.83, 95% confidence interval [95% CI] 1.18-6.76). This higher frequency of the 4G allele was attributable to the higher frequency in patients with versus those without arterial thrombosis (0.64 versus 0.43; P < 0.01) (OR 5.96, 95% CI 1.67-21.32), while patients with venous thrombosis had an allele distribution similar to that of those without venous thrombosis (0.49 versus 0.50; P not significant). There was a trend toward higher PAI-1 antigen and activity levels in APS patients and controls with the 4G/4G genotype, but this did not reach statistical significance.

CONCLUSION

The presence of the 4G allele of the 4G/5G polymorphism of the PAI-1 gene may be an additional risk factor for the development of arterial thrombosis in APS.

Deficient APC-cofactor activity of protein S Heerlen in degradation of factor Va Leiden: a possible mechanism of synergism between thrombophilic risk factors

In protein S Heerlen, an S-to-P (single-letter amino acid codes) mutation at position 460 results in the loss of glycosylation of N458. This polymorphism has been found to be slightly more prevalent in thrombophilic populations than in normal controls, particularly in cohorts of patients having free protein S deficiency. This suggests that carriers of the Heerlen allele may have an increased risk of thrombosis. We have now characterized the expression in cell cultures of recombinant protein S Heerlen and investigated the anticoagulant functions of the purified recombinant protein in vitro. Protein S Heerlen was synthesized and secreted equally well as wild-type protein S by transiently transfected COS-1 cells. The recombinant protein S Heerlen interacted with conformation-dependent monoclonal antibodies and bound C4b-binding protein to the same extent as wild-type protein S. Protein S Heerlen displayed reduced anticoagulant activity as cofactor to activated protein C (APC) in plasma-based assays, as well as in a factor VIIIa–degradation system. In contrast, protein S Heerlen functioned equally well as an APC cofactor in the degradation of factor Va as wild-type protein S did. However, when recombinant activated factor V Leiden (FVa:Q506) was used as APC substrate, protein S Heerlen was found to be a poor APC cofactor as compared with wild-type protein S. These in vitro results suggest a possible mechanism of synergy between protein S Heerlen and factor V Leiden that might be involved in the pathogenesis of thrombosis in individuals carrying both genetic traits.

Deficient APC-cofactor activity of protein S Heerlen in degradation of factor Va Leiden: a possible mechanism of synergism between thrombophilic risk factors

In protein S Heerlen, an S-to-P (single-letter amino acid codes) mutation at position 460 results in the loss of glycosylation of N458. This polymorphism has been found to be slightly more prevalent in thrombophilic populations than in normal controls, particularly in cohorts of patients having free protein S deficiency. This suggests that carriers of the Heerlen allele may have an increased risk of thrombosis. We have now characterized the expression in cell cultures of recombinant protein S Heerlen and investigated the anticoagulant functions of the purified recombinant protein in vitro. Protein S Heerlen was synthesized and secreted equally well as wild-type protein S by transiently transfected COS-1 cells. The recombinant protein S Heerlen interacted with conformation-dependent monoclonal antibodies and bound C4b-binding protein to the same extent as wild-type protein S. Protein S Heerlen displayed reduced anticoagulant activity as cofactor to activated protein C (APC) in plasma-based assays, as well as in a factor VIIIa–degradation system. In contrast, protein S Heerlen functioned equally well as an APC cofactor in the degradation of factor Va as wild-type protein S did. However, when recombinant activated factor V Leiden (FVa:Q506) was used as APC substrate, protein S Heerlen was found to be a poor APC cofactor as compared with wild-type protein S. These in vitro results suggest a possible mechanism of synergy between protein S Heerlen and factor V Leiden that might be involved in the pathogenesis of thrombosis in individuals carrying both genetic traits.

Influence of the -675 4G/5G dimorphism of the plasminogen activator inhibitor 1 promoter on thrombotic risk in patients with factor V Leiden

Elevated plasminogen activator inhibitor 1 (PAI-1) levels are associated with venous thromboembolism, although their significance is unclear. PAI-1 levels are influenced by a PAI-1 promoter dimorphism (4G/5G), the 4G allele being associated with increased PAI-1 activity. We investigated whether the 4G allele influenced thrombotic risk by studying 99 symptomatic factor V (FV) Leiden heterozygotes and 99 healthy subjects. The 4G allele was more prevalent among cases than among healthy subjects (chi2 = 8.00, P = 0.005) and the odds ratio (OR) for thrombosis associated with either heterozygosity or homozygosity for the 4G allele was 2.43 (P = 0. 011). We conclude that carriership of the 4G allele was more prevalent in patients who already carried factor V Leiden than in control subjects without factor V Leiden.

The A -844G polymorphism in the PAI-1 gene is associated with a higher risk of venous thrombosis in factor V Leiden carriers

Identification of combined genetic factors in factor V Leiden carriers is important for a more accurate risk assessment for venous thrombosis (VT). Among these individuals, we evaluated the role of polymorphisms of the plasminogen activator inhibitor-1 (PAI-1) gene in the thrombophilic phenotype. A total of 382 factor V Leiden carriers were included in the study. This population was divided into 3 groups. Group 1 (n=168) included individuals with a personal history of VT; group 2 (n=140) included individuals without personal VT but with a familial history of VT; and group 3 (n=74) included individuals without VT and with a fortuitous discovery of the factor V Leiden mutation. We compared the genotype distribution of 2 polymorphisms, A -844G and -675 4G/5G, located in the promoter region of the PAI-1 gene among these 3 groups of individuals. The A -844G allele frequency differed significantly among the 3 groups (P=0.048), the A allele being more frequent in patients who suffered from VT (61%) than in subjects without VT (52%, P=0.015), whereas no difference was observed between the 2 groups of asymptomatic individuals. The prevalence of genotype AA carriers was higher in patients with VT (38%) than in asymptomatic individuals (21%, P=0. 015), leading to an odds ratio of 1.74 (95% confidence interval, 1.3 to 3.8). Carrying the AA genotype conferred a risk of deep VT of 2. 08 (95% confidence interval, 1.28 to 3.40), whereas it did not seem to significantly influence the risk of pulmonary embolism. Concerning the -675 4G/5G polymorphism, no significant difference was observed among the 3 groups, the 4G allele frequency being 0.54 (in group 1), 0.49 (in group 2), and 0.45 (in group 3). These data suggest a role for the -A844G PAI-1 gene polymorphism in the thrombophilic phenotype of factor V Leiden carriers.

Effect of plasminogen activator inhibitor-1 4G/5G polymorphism in Turkish deep vein thrombotic patients with and without FV1691 G-A

A decreased fibrinolytic activity due to increased levels of plasminogen activator inhibitor-1 has been shown in deep vein thrombosis patients. Elevated plasma plasminogen activator inhibitor-1 levels are associated with the 4G allele of a 4G/5G polymorphism located in the promoter region of the plasminogen activator inhibitor-1 gene. Because there is no existing data in the Turkish population, we aimed to study these mutations in patients with deep vein thrombosis (n = 136) and normal controls (n = 113), consecutively selected among unrelated healthy subjects without personal and familial history of atherothrombosis from Ankara, Turkey. DNA was extracted by conventional methods, and polymerase chain reaction of the plasminogen activator inhibitor-1 4G/5G polymorphism was performed according to a previously described method. Genotype distributions of FV 1691G-A and plasminogen activator inhibitor-1 4G/5G are as follows: plasminogen activator inhibitor-1 4G (patients) 0.562, plasminogen activator inhibitor-1 4G (controls) 0.50 (p = 0.6); FV1691A (patients) 0.147, FV1691A (controls) 0.035 (p = 0.005). Our data indicated that plasminogen activator inhibitor-1 4G/5G does not have an effect on the thrombotic risk. Carrying the 4G allele either in heterozygous or homozygous state increases the risk in the presence of FV1691A (odds ratio: 9.8 and 6.9, confidence interval 95% 2.9-32.7 and 1.3-35.8). FV1691A is an independent risk factor for thrombosis (odds ratio: 5.5, confidence interval: 95% 2.5-12.1). We concluded that coexistence of FV1691A and plasminogen activator inhibitor-1 4G allele leads to an increased risk for thrombosis leading a further evidence to another prothrombotic factor that may be necessary for the development of a manifest thrombotic event.

Coinheritance of the HR2 Haplotype in the Factor V Gene Confers an Increased Risk of Venous Thromboembolism to Carriers of Factor V R506Q (Factor V Leiden)

With the aim of establishing whether the HR2 haplotype in factor V affects the risk of venous thromboembolism, a retrospective multicenter cohort study was performed in 810 family members identified through 174 probands who suffered from at least 1 episode of deep vein thrombosis and/or pulmonary embolism and had an inherited defect associated with thrombophilia (antithrombin, protein C, or protein S deficiency; factor V R506Q or prothrombin G20210A). Fifty-eight percent (468/810) of the family members had an inherited defect and 10% (47/468) were symptomatic. The HR2 haplotype was found in association with factor V R506Q more frequently in family members with venous thromboembolism (18%) than in those without (8%). Double heterozygosity for factor V R506Q and HR2 conferred a 3- to 4-fold increase in the relative risk of venous thromboembolism compared with factor V R506Q alone. The median age at first event was lower when the 2 defects were associated (46v 52 years). No increase in risk of venous thromboembolism could be demonstrated when the HR2 haplotype was associated with inherited thrombophilic defects other than factor V R506Q. Because both factor V R506Q and the HR2 haplotype are very frequent, the effect of their coinheritance on the risk of venous thromboembolism might represent a clinically relevant issue, and screening for HR2 in carriers of factor V R506Q should be considered.

Coinheritance of the HR2 Haplotype in the Factor V Gene Confers an Increased Risk of Venous Thromboembolism to Carriers of Factor V R506Q (Factor V Leiden)

With the aim of establishing whether the HR2 haplotype in factor V affects the risk of venous thromboembolism, a retrospective multicenter cohort study was performed in 810 family members identified through 174 probands who suffered from at least 1 episode of deep vein thrombosis and/or pulmonary embolism and had an inherited defect associated with thrombophilia (antithrombin, protein C, or protein S deficiency; factor V R506Q or prothrombin G20210A). Fifty-eight percent (468/810) of the family members had an inherited defect and 10% (47/468) were symptomatic. The HR2 haplotype was found in association with factor V R506Q more frequently in family members with venous thromboembolism (18%) than in those without (8%). Double heterozygosity for factor V R506Q and HR2 conferred a 3- to 4-fold increase in the relative risk of venous thromboembolism compared with factor V R506Q alone. The median age at first event was lower when the 2 defects were associated (46v 52 years). No increase in risk of venous thromboembolism could be demonstrated when the HR2 haplotype was associated with inherited thrombophilic defects other than factor V R506Q. Because both factor V R506Q and the HR2 haplotype are very frequent, the effect of their coinheritance on the risk of venous thromboembolism might represent a clinically relevant issue, and screening for HR2 in carriers of factor V R506Q should be considered.

Changes in levels of factor VII and protein S after acute myocardial infarction: effects of low-dose warfarin

Persistent coagulation activity after an acute myocardial infarction may increase the risk of reinfarction. We prospectively investigated the effects on plasma coagulation of a low, fixed dose of warfarin in combination with aspirin after myocardial infarction. We also evaluated the influence of coagulation activity on clinical outcome. Plasma samples from 97 patients, randomised to 1.25 mg of warfarin daily in combination with 75 mg of aspirin or aspirin alone were drawn 4 days, 1 month, and 6 months after myocardial infarction. Patients receiving warfarin had a greater reduction in factor VII coagulation activity (FVII:C) after 6 months: 0.18 vs. 0.06 U/mL,(95% CI, 0.02-0.22), whereas no differences were seen in levels of protein C, protein S, or prothrombin fragment 1+2. In the acute phase, the level of free protein S was lower than after 6 months in both groups: 25.6 vs. 28.8% (95% CI, 4.19--2.35). Cardiovascular mortality, reinfarction, and stroke were evaluated after 4 years (median). In a survival analysis, every 0.1 U/mL increase in the level of FVII:C1 month after myocardial infarction was associated with an 15% increase in risk of cardiovascular events (95% C1, 1.01-1.30). Warfarin at 1.25 mg daily reduces FVII:C but not systemic thrombin generation measured as prothrombin fragment 1 +2. Low levels of the anticoagulant protein S may contribute to a procoagulant state.

Update on genetic risk factors for thrombosis and atherosclerotic vascular disease

The strong familial occurrence of venous and arterial thromboembolic disease has prompted ongoing research to identify novel risk factors. Polymorphisms in the factor VII and prothrombin genes are related to increased thrombosis, but the mechanism of increased risk remains to be elucidated. Elevated levels of plasma homocysteine and of the variant lipoprotein(a) particle also contribute to increased thrombotic risk, due in part to polymorphisms in the apolipoprotein(a) gene and the gene for methylene tetrahydrofolate reductase.