Endothelial cell protein C receptor (EPCR) enhances the generation of activated protein C (APC) by the thrombin-thrombomodulin complex. A soluble form of EPCR (sEPCR), which is generated by metalloprotease activity, is present in plasma. The distribution of sEPCR levels in healthy populations is bimodal. Previously, we described two polymorphisms in exon 4 of the EPCR gene, 4600A/G that encodes the substitution of Ser219 by Gly in the transmembrane region of EPCR and 4678G/C in the 3'-UT region. The aim of this study was to investigate the relationship between these two polymorphisms and plasma sEPCR and APC levels and risk of venous thrombosis. We genotyped 401 healthy controls from the Spanish population and measured their plasma sEPCR and APC levels. Carriers of the 4600AG genotype had significantly higher sEPCR levels than those with the AA genotype, while the 4678CC genotype was associated, to a lesser extent, with elevated APC levels. To assess the effect of these polymorphisms on the risk of thrombosis, we genotyped 405 patients with venous thromboembolism. The frequency of the 4600AG genotype was very similar in patients and controls (p=0.975), whereas the 4678CC genotype was significantly more frequent in controls than in patients (p=0.008). In multivariate analysis, carriers of the 4678CC genotype had a decreased risk of thrombosis (OR=0.61, p=0.009). These data indicate that individuals carrying the 4600AG genotype have high sEPCR levels but do not have an increased risk of thrombosis, whereas individuals carrying the 4678CC genotype have higher APC levels and lower risk of venous thromboembolism.

Summary. To ascertain the potential contribution of serum lipids to the development of deep vein thrombosis (DVT), a case-control study was conducted in 143 DVT patients lacking thrombophilic risk factors and in 194 age-and sexmatched controls. DVT patients showed significantly higher body mass indices (BMI), and triglyceride levels than did controls (P < 0AE001 and P ¼ 0AE045 respectively). Using multivariate analysis, BMI was the only variable which remained statistically different, thus the risk of DVT was associated with obesity (odds ratio ¼ 2AE49). These results were confirmed when additional control for fibrinogen and plasminogen activator inhibitor type 1 (PAI-1) was carried out in a subgroup of cases and controls. When idiopathic (n ¼ 39) and secondary (n ¼ 104) patients with DVT were compared, the former showed a higher mean age, a higher proportion of men, and higher cholesterol levels. Age, sex and total cholesterol were statistically different by multivariate analysis. After age was dichotomized as ‡ 50 years and cholesterol ‡ 5AE69 mmol/l, all three variables constituted independent risk factors for idiopathic DVT, with odds ratios of 2AE73 for ages ‡ 50 years; 3AE72 for men and 2AE67 for cholesterolaemia ‡ 5AE69 mmol/l. Obesity thus constitutes an independent risk factor for DVT, possibly in part mediated through triglyceride, fibrinogen and PAI-1 effects on haemostasis. In addition, cholesterolaemia levels of ‡ 5AE69 mmol/l constitute an independent risk factor for idiopathic DVT.

BackgroundHaplotypes A1 and A3 in the endothelial protein C receptor (EPCR) gene are tagged by 4678G/C and 4600A/G respectively. We assessed whether these haplotypes modify the risk of venous thromboembolism in carriers of the prothrombin 20210A allele.

Summary. 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.

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.

Objective— To investigate the association of the THBD c.1418C>T polymorphism, which encodes for the replacement of Ala455 by Val in thrombomodulin (TM), with venous thromboembolism (VTE), plasma soluble TM, and activated protein C levels. In addition, human umbilical vein endothelial cells (HUVEC) isolated from 100 umbilical cords were used to analyze the relation between this polymorphism and THBD mRNA and TM protein expression. Approach and Results— The THBD c.1418C>T polymorphism was genotyped in 1173 patients with VTE and 1262 control subjects. Levels of soluble TM and activated protein C were measured in 414 patients with VTE (not on oral anticoagulants) and 451 controls. HUVECs were genotyped for the polymorphism and analyzed for THBD mRNA and TM protein expression and for the ability to enhance protein C activation by thrombin. The 1418T allele frequency was lower in patients than in controls ( P <0.001), and its presence was associated with a reduced VTE risk, reduced soluble TM levels, and increased circulating activated protein C levels ( P <0.001). In cultured HUVEC, the 1418T allele did not influence THBD expression but was associated with increased TM in cell lysates, increased rate of protein C activation, and reduced soluble TM levels in conditioned medium. Conclusions— The THBD 1418T allele is associated with lower soluble TM, both in plasma and in HUVEC-conditioned medium, and with an increase in functional membrane–bound TM in HUVEC, which could explain the increased activated protein C levels and the reduced VTE risk observed in individuals carrying this allele.

SummaryHeparin cofactor II (HCII) is a specific inhibitor of thrombin in the presence of heparin or dermatan sulphate. Although there have been reports on families in which a heterozygous HCII deficiency is associated with thromboembolic events, several epidemiological studies revealed that heterozygous HCII deficiency is as prevalent among healthy subjects as it is among patients with deep venous thrombosis (DVT). It is therefore not yet clear whether HCII is or is not a thrombotic risk factor.We analyze and describe in an extended family the biochemical and genetic thrombophilic risk factors and evaluate the potential thrombotic risk involved in homozygous and heterozygous HCII deficiency, either alone or associated with other thrombotic or circumstantial risk factors. The propositus has had three episodes of DVT and a pulmonary embolism. During the first episode of DVT the patient was diagnosed as having AT deficiency. Later, a functional and antigenic HCII deficiency, compatible with the homozygous form, was detected. The family study shows that both the propositus and her sister have homozygous HCII deficiency and that 12 of the 27 family members have heterozygous HCII deficiency.This is possibly the first case report on a homozygous phenotype for the HCII deficiency with, in addition, partial AT deficiency. The propositus has suffered several thrombotic events, unlike the other 12 family members with heterozygous HCII deficiency and her sister, who is also homozygous for this disorder. We suggest that HCII deficiency may play a limited in vivo role as a thrombotic risk factor unless associated with AT deficiency or another congenital thrombotic risk factor.

The association between factor V Leiden (FVL) and prothrombin G20210A (PT 20210) mutations and ischemic stroke remains controversial, particularly in young adults with cryptogenic stroke. Prevalence of FVL (4.1%) and PT 20210 (8.2%) mutations was assessed in 49 patients under 50 years with cryptogenic stroke and compared with controls. Odd ratio (OR) for cryptogenic stroke was 2.62 (95% CI, 0.49-13.95) for FVL and 3.75 (95% CI, 1.05-13.34) for PT 20210 and 3.28 (95% CI, 1,17-9.20) for some recognized genetic thrombophilic defect. Moreover, the OR for cryptogenic stroke in young women using oral contraceptives (OC) was 3.59 (95% CI, 1.28-10.5). When some genetic thrombophilic defect was associated with OC, the OR was much higher (OR: 14.27; 95% CI, 0.66-309.99). Our results suggest that in the Mediterranean populations the PT 20210 mutation, but not FV Leiden, is a risk factor for cryptogenic stroke in young adults. OC use is also a significant risk factor for cryptogenic stroke, which is increased in women with some genetic thrombotic risk factor.