Jordi Fontcuberta

Increased fetal loss in women with heritable thrombophilia.

BACKGROUND A successful outcome of pregnancy requires an efficient uteroplacental vascular system. Since this system may be compromised by disorders of haemostasis associated with a prothrombotic state, we postulated that maternal thrombophilia might be a risk factor for fetal loss. We studied the relation between heritable thrombophilic defects and fetal loss in a cohort of women with factor V Leiden or deficiency of antithrombin, protein C, or protein S. METHODS We studied 1384 women enrolled in the European Prospective Cohort on Thrombophilia (EPCOT). Of 843 women with thrombophilia 571 had 1524 pregnancies; of 541 control women 395 had 1019 pregnancies. The controls were partners of male members of the EPCOT cohort or acquaintances of cases. We analysed the frequencies of miscarriage (fetal loss at or before 28 weeks of gestation) and stillbirth (fetal loss after 28 weeks of gestation) jointly and separately. FINDINGS The risk of fetal loss was increased in women with thrombophilia (168/571 vs 93/395; odds ratio 1.35 [95% Cl 1.01-1.82]). The odds ratio was higher for stillbirth than for miscarriage (3.6 [1.4-9.4] vs 1.27 [0.94-1.71]). The highest odds ratio for stillbirth was in women with combined defects (14.3 [2.4-86.0]) compared with 5.2 (1.5-18.1) in antithrombin deficiency, 2.3 (0.6-8.3) in protein-C deficiency, 3.3 (1.0-11.3) in protein-S deficiency, and 2.0 (0.5-7.7) with factor V Leiden. The corresponding odds ratios for miscarriage in these subgroups were 0.8 (0.2-3.6), 1.7 (1.0-2.8), 1.4 (0.9-2.2), 1.2 (0.7-1.9), and 0.9 (0.5-1.5). Significantly more pregnancy terminations had been done in women with thrombophilia than in controls (odds ratio 2.9 [1.8-4.8]); this discrepancy was apparent in nine of 11 participating centres and for all thrombophilia subgroups. INTERPRETATION Women with familial thrombophilia, especially those with combined defects or antithrombin deficiency, have an increased risk of fetal loss, particularly stillbirth. Our findings have important implications for therapy and provide a rationale for clinical trials of thromboprophylaxis for affected women with recurrent fetal loss.

Genetic Susceptibility to Thrombosis and Its Relationship to Physiological Risk Factors: The GAIT Study

Although there are a number of well-characterized genetic defects that lead to increased risk of thrombosis, little information is available on the relative importance of genetic factors in thrombosis risk in the general population. We performed a family-based study of the genetics of thrombosis in the Spanish population to assess the heritability of thrombosis and to identify the joint actions of genes on thrombosis risk and related quantitative hemostasis phenotypes. We examined 398 individuals in 21 extended pedigrees. Twelve pedigrees were ascertained through a proband with idiopathic thrombosis, and the remaining pedigrees were randomly ascertained. The heritability of thrombosis liability and the genetic correlations between thrombosis and each of the quantitative risk factors were estimated by means of a novel variance component method that used a multivariate threshold model. More than 60% of the variation in susceptibility to common thrombosis is attributable to genetic factors. Several quantitative risk factors exhibited significant genetic correlations with thrombosis, indicating that some of the genes that influence quantitative variation in these physiological correlates also influence the risk of thrombosis. Traits that exhibited significant genetic correlations with thrombosis included levels of several coagulation factors (factors VII, VIII, IX, XI, XII, and von Willebrand), tissue plasminogen activator, homocysteine, and the activated protein C ratio. This is the first study that quantifies the genetic component of susceptibility to common thrombosis. The high heritability of thrombosis risk and the significant genetic correlations between thrombosis and related risk factors suggest that the exploitation of correlated quantitative phenotypes will aid the search for susceptibility genes.

Prothrombotic state and signs of endothelial lesion in plasma of patients with inflammatory bowel disease

Recent investigations suggest that microthrombi formation in bowel capillaries could be a determinant factor in inflammatory bowel disease (IBD) pathogenesis. To evaluate the implication of the hemostatic system during these thrombotic events, we analyzed plasmatic values of prothrombotic state markers, physiologic inhibitors of coagulation, and endothelial lesion markers in 112 IBD patients. We found an increase in thrombin-antithrombin complexes and a decrease in antithrombin III, probably due to consumption, demonstrating an increase in thrombin generation. High levels ofd-dimer reflect increased fibrin formation, but there is no correlation between thrombin generation markers andd-dimer, possibly suggesting the presence of inadequate fibrinolysis. Levels of tissue factor pathway inhibitor were higher in patients than in controls. Nine patients with Crohns disease (35% of our sample) had levels of this marker under 70% (range 37–69%). Von Willebrand factor values were increased and those of thrombomodulin only in active patients. Most of the changes were detected in patients with inflammatory activity, and there were no differences between ulcerative colitis and Crohns disease. In conclusion, these results support the hypothesis that there is an endothelial lesion with sustained coagulation activation in IBD patients.

A genomewide exploration suggests a new candidate gene at chromosome 11q23 as the major determinant of plasma homocysteine levels: results from the GAIT project.

Homocysteine (Hcy) plasma level is an independent risk marker for venous thrombosis, myocardial infarction, stroke, congestive heart failure, osteoporotic fractures, and Alzheimer disease. Hcy levels are determined by the interaction of genetic and environmental factors. The genetic basis is still poorly understood, since only the MTHFR 677 C-->T polymorphism has been consistently associated with plasma Hcy levels. We conducted a genomewide linkage scan for genes affecting variation in plasma Hcy levels in 398 subjects from 21 extended Spanish families. A variance-components linkage method was used to analyze the data. The strongest linkage signal (LOD score of 3.01; genomewide P = .035) was found on chromosome 11q23, near marker D11S908, where a candidate gene involved in the metabolism of Hcy (the nicotinamide N-methyltransferase gene [NNMT]) is mapped. Haplotype analyses of 10 single-nucleotide polymorphisms within this gene found one haplotype associated with plasma Hcy levels (P = .0003). Our results, to our knowledge, represent the first genomic scan for quantitative variation in Hcy plasma levels. They strongly suggest that the NNMT gene could be a major genetic determinant of plasma Hcy levels in Spanish families. Since this gene encodes an enzyme involved in Hcy synthesis, this finding would be consistent with known biochemical pathways. These data could be relevant in determining the relationships between Hcy level, cardiovascular disease, osteoporosis, and Alzheimer disease.

A quantitative-trait locus in the human factor XII gene influences both plasma factor XII levels and susceptibility to thrombotic disease.

One approach to the identification of genetic loci that influence complex diseases is through the study of quantitative risk factors correlated with disease susceptibility. Factor XII (FXII) plasma levels, a related phenotype correlated with thrombosis, is such a risk factor. We conducted the first genomewide linkage screen to localize genes that influence variation in FXII levels. Two loci were detected: one on chromosome 5 and another on chromosome 10 (LOD scores 4.73 and 3.53, respectively). On chromosome 5, the peak LOD score occurred in the 5q33-5ter region, near the FXII gene. Addition of a 46C/T mutation in the FXII gene increased the multipoint LOD score to 10.21 (P=3.6 x 10(-12)). A bivariate linkage analysis of FXII activity and thrombosis further improved the linkage signal (LOD = 11.73) and provided strong evidence that this quantitative-trait locus (QTL) has a pleiotropic effect on the risk of thrombosis (P=.004). Linkage analysis conditional on 46C/T indicated that this mutation alone cannot explain the chromosome 5 signal, implying that other functional sites must exist. These results represent the first direct genetic evidence that a QTL in or near the FXII gene influences both FXII activity and susceptibility to thrombosis and suggest the presence of one or more still unknown functional variants in FXII.

The ABO blood group genotype and factor VIII levels as independent risk factors for venous thromboembolism

Factor VIII (FVIII), von Willebrand factor (vWF) and the ABO blood groups have been associated with thrombosis. The ABO locus has functional effects on vWF and FVIII levels and is genetically correlated with FVIII, vWF and thrombosis. We carried out a case-control study to assess the role of FVIII, vWF and ABO types on thrombotic risk. We analyzed 250 patients with venous thrombosis and 250 unrelated controls. FVIII, vWF and other factors related to thrombophilia were measured, ABO groups were analyzed by genotyping. FVIII and vWF were higher in non-O individuals. Group O was more frequent in the controls (44.3% v 23.3%; difference 21.1%; 95% CI: 13.0-29.3%) and Group A in patients (59.2% v. 41.5%; difference 17.7%, 95% CI: 9.1-26.4%). Individuals carrying the A1 allele had a higher risk of thrombosis (OR 2.6; 95% CI, 1.8-3.8). The risk attributed to vWF disappeared after adjusting for the ABO group. Patients with FVIII above the 90th percentile had a high thrombotic risk (adjusted OR 3.7; 95% CI, 2.1-6.5), and a high risk of recurrence (OR 2.3; 95% CI: 1.3-4.1). In conclusion, high FVIII levels and non-O blood groups, likely those with the A1 allele, are independent risk factors for venous thromboembolism and should be considered in evaluating of thrombophilia.

Recurrence Rate After a First Venous Thrombosis in Patients With Familial Thrombophilia

Objective—Few comprehensive data are available on the recurrence rate of venous thrombosis in carriers of thrombophilic defects from thrombophilic families. We prospectively determined the recurrence rate after a first venous thrombotic event in patients with familial thrombophilia attributable to factor V Leiden or deficiencies of protein C, S, or antithrombin. Methods and Results—Data were gathered during follow-up on the occurrence of risk situations, anticoagulation treatment, and events (eg, venous thrombosis, hemorrhage). Over a mean follow-up period of 5.6 years, 44 of the 180 patients with familial thrombophilia who did not use long-term anticoagulation experienced a recurrent venous thromboembolic event (5.0%/year; 95% CI 3.6 to 6.7) compared with 7 of the 124 patients on long-term anticoagulation (1.1%/year; 95% CI 0.4 to 2.2). Spontaneous events occurred less often in patients on long-term anticoagulation (57%) than in patients without long-term anticoagulation (75%). The highest recurrence rate was found among men with a deficiency in natural anticoagulants or multiple defects and women with antithrombin deficiency. Although long-term anticoagulation treatment decreased the incidence of recurrent events by 80%, it also resulted in a risk of major hemorrhage of 0.8% per year. Conclusions—Extra care after a first event is required for men with a deficiency in natural anticoagulants or multiple defects and women with antithrombin deficiency.

Association after linkage analysis indicates that homozygosity for the 46C-->T polymorphism in the F12 gene is a genetic risk factor for venous thrombosis.

In a family-based study called GAIT (Genetic Analysis of Idiopathic Thrombophilia) that included a genome-wide scan we demonstrated that a polymorphism (46C-->T) in the F12 locus jointly influences variability of plasma (Factor XII) FXII levels and susceptibility to thrombotic disease. It then became germane to determine the prevalence of the 46C-->T polymorphism and its relative risk of thrombotic disease. We followed up evidence for genetic linkage with a case-control study, including 250 unrelated consecutive Spanish patients suffering from venous thrombotic disease and 250 Spanish subjects matched for sex and age as a controls. We measured FXII levels and genotyped the 46C-->T polymorphism, as well as a number of classical risk factors for thrombotic disease. We confirmed that individuals with different genotypes for this polymorphism showed significant differences in their FXII levels. Most importantly, the mutated T allele in the homozygous state (genotype T/T) was associated with an increased risk of thrombosis (adjusted OR of 4.82; 95% CI 1.5-15.6), suggesting that the polymorphism itself is an independent risk factor for venous thromboembolism. This study confirms that the 46C-->T polymorphism is a genetic risk factor for venous thrombosis in the Spanish population. In addition, our results confirm that a genome-wide scan coupled with a classical case-control association study is an extremely valuable approach to identify DNA variants that affect complex diseases.

Aprotinin versus desmopressin for patients undergoing operations with cardiopulmonary bypass: A double-blind placebo-controlled study

BACKGROUND Aprotinin reduces blood loss in operations done with cardiopulmonary bypass, whereas the use of desmopressin remains controversial. We compared aprotinin, desmopressin, and placebo in a double-blind, randomized trial to evaluate bleeding and transfusion requirements. METHODS AND RESULTS One hundred forty-nine patients (48 received aprotinin, 50 desmopressin, 51 placebo) were included. Blood loss and transfusion requirements were recorded and levels of Factor VIII coagulant activity, von Willebrands factor, thrombin-antithrombin complexes, and D-dimer were measured. Overall blood loss was 195 +/- 146 ml/m2 in the aprotinin group, 400 +/- 192 ml/m2 in the desmopressin group, and 489 +/- 361 ml/m2 in the placebo group (95% confidence intervals: difference between desmopressin and aprotinin 98 to 312 ml/m2, p < 0.001; difference between placebo and aprotinin 190 to 398 ml/m2, p < 0.001). Twenty-six percent of patients treated with aprotinin, 66% of those treated with desmopressin, and 56% of those treated with placebo were given transfusion (95% confidence intervals: difference between aprotinin versus placebo plus desmopressin 51% to 71%, p < 0.001). Fibrinolytic activation throughout cardiopulmonary bypass was markedly higher with placebo or desmopressin administration. D-dimer level correlated with overall blood loss in patients receiving desmopressin or placebo, but not in those receiving aprotinin. CONCLUSION Aprotinin administration reduces blood loss and transfusion requirements in cardiopulmonary bypass. This benefit may be explained by a lower activation of fibrinolysis.

Short-course thrombolysis as the first line of therapy for cardiac valve thrombosis

OBJECTIVE To retrospectively evaluate the clinical and echocardiographic criteria of thrombolytic therapy for mechanical heart valve thrombosis. METHODS Nineteen consecutive patients with 22 instances of prosthetic heart valve thrombosis (14 mitral, 2 aortic, 3 tricuspid, and 3 pulmonary) were treated with short-course thrombolytic therapy as first option of treatment in absence of contraindications. The thrombolytic therapy protocol consisted of streptokinase (1,500,000 IU in 90 minutes) (n = 18) in one (n = 7) or two (n = 11) cycles or recombinant tissue-type plasminogen activator (100 mg in 90 minutes) (n = 4). RESULTS Overall success was seen in 82%, immediate complete success in 59%, and partial success in 23%. Six patients without total response to thrombolytic therapy underwent surgery, and pannus was observed in 83%. Six patients showed complications: allergy, stroke, transient ischemic attack, coronary embolism, minor bleeding, and one death. At diagnosis, 10 patients evidenced atrial thrombus by transesophageal echocardiography, 3 of whom experienced peripheral embolism during thrombolysis. Four episodes of rethrombosis were observed (16%). The survivorship was 84% with a mean follow-up of 42.6 months. CONCLUSIONS A short-course of thrombolytic therapy may be considered first-line therapy for prosthetic heart valve thrombosis. The risk of peripheral embolism may be evaluated for the presence of atrial thrombus by transesophageal echocardiography at diagnosis.