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PubMed1999

Venous thromboembolism at a young age in a brother and sister with coinheritance of homozygous 20210A/A prothrombin mutation and heterozygous 1691G/A factor V Leiden mutation.

We report on members of a Turkish thrombophilic family with coinheritance of the prothrombin mutation PT20210A and the factor V Leiden mutation. The 23-year-old propositus and his elder sister both had episodes of venous theomboembolism at a young age (23 years and 26 years, respectively) and are homozygous for the PT20210A mutation and heterozygous for the factor V Leiden mutation. The 51-year-old father is suffering from coronary heart disease and is heterozygous for both thrombophilic mutations. The asymptomatic 43-year-old mother is heterozygous for the PT20210A mutation, but without activated protein C resistance. Two other children, a 20-year-old girl who is homozygous for the PT20210A mutation and a 13-year-old boy who is heterozygous for the PT20210A mutation, are both free from activated protein C resistance and thrombosis. This report provides further evidence for an early onset of thromboembolic disorders in individuals with an homozygous state of the prothrombin variant 20210A/A and coinheritance of another thrombophilic mutation. Consensus guidelines are required for the treatment and prophylaxis of patients and subjects who remain asymptomatic with homozygous or more than one heterozygous genetic defect associated with thrombophilia.

Adult↗
PubMed1999

Early occlusion of coronary by-pass associated with the presence of factor V Leiden and the prothrombin 20210A allele: case report.

The presence of factor V Leiden mutation and the variation of the prothrombin gene 20210GA have been described as additional risk factors for arterial thrombosis when other acquired or metabolic risk factors are present. We report here a 56-year-old man who developed coronary artery disease since 1980 without any known risk factor and underwent a cardiopulmonary by-pass in 1997. In the first month after surgery, he became symptomatic, and an angiography showed complete occlusion of the grafts and some native coronary arteries. Three months after the second cardiopulmonary by-pass, a thrombophilic state was searched, and plasma levels of lipoprotein (a) (LPa) were measured. The patient is heterozygous for factor V Leiden mutation and has the variation 20210GA of the prothrombin gene and high levels of LPa. These findings induced us to add oral anticoagulation to the aspirin treatment, and the patient is in a good condition 11 months later.

Coronary Artery Bypass↗
PubMed2001

Impact of plasma homocysteine and prothrombin G20210 A on primary antiphospholipid syndrome.

The prevalence of prothrombin (PT) G20210A and methylenetetrahydrofolate reductase (MTHFR) C677 <-- T was assessed in 40 patients with primary antiphospholipid syndrome (APS) (14 male, 26 female; mean age, 37 +/- 14 years) and in 27 persistent carriers of antiphospholipid antibodies (aPL) (five male, 22 female; mean age, 40 +/- 16 years) without underlying diseases. Non-APS thrombotic patients (n = 100; 47 female, 53 male; mean age, 40 +/- 10 years) and healthy subjects (n = 100; 46 female, 54 male; mean age, 56 +/- 16 years) served as control groups. Plasma homocysteine (HC) (enzyme-linked immunosorbent assay) was measured in all aPL patients and in 51 subjects from the healthy control group (mean age, 38 +/- 16 years). Heterozygous prothrombin PT G20210A was more frequent in the thrombotic group without APS (18%) than in the control (4%), APS (12%) or aPL (11%) groups, whereas homozygous MTHFR C677 <-- T was equally distributed. After genotype sub-grouping, plasma HC was higher in APS patients with homozygous MTHFR C677 <-- T compared with non-homozygous APS patients (22 +/- 5.4 versus 11 +/- 1.3 micromol/l; P < 0.01) and with homozygous MTHFR C677 <-- T controls (22 +/- 5.4 versus 15 +/- 2.0 micromol/l). In the APS group, mean age at first event was lower in homozygous MTHFR C677 <-- T patients than in non-homozygous patients (26 +/- 7.5 versus 36 +/- 13 years; P = 0.008). In the same group, homozygous MTHFR C677 <-- T patients suffered an increased average number of events per person than non-homozygous patients (1.9 versus 1.3; P = 0.04). Heterozygous PT G20210A contributes little to the thrombotic tendency of primary APS whereas plasma HC may influence age at first event and number of events. Measurement of plasma HC in aPL subjects may identify patients at increased thrombotic risk requiring HC lowering.

Adult↗
PubMed2002

Comparative evaluation of five different methods for the measurement of plasma factor II levels in carriers of the 20210A prothrombin variant.

The common genetic G to A variation of the prothrombin gene is associated with elevated levels of prothrombin [factor II (FII)] and is recognized as a risk factor for thrombosis. To determine whether one type of assay for plasma FII measurement was more efficient than other assays in displaying high FII levels in 20210A carriers, we compared five methods of measuring FII levels [i.e. an enzyme-linked immunosorbent assay (ELISA), a standard clotting assay, and three chromogenic methods using three different activators: Ecarin, Oxyuranus, and Textarin] in 30 G20210A patients and 30 G20210G controls. Plasma concentrations of factor X and factor VII + factor X were also determined by a clotting procedure. Functional assays were found to be equally efficient in demonstrating significantly higher FII levels in 20210A carriers than in non-carriers (P < 0.0001). With ELISA, the difference observed was less significant (P < 0.005). The specificity of every assay increased with FII cut-off levels; when a cut-off of 115% was applied, sensitivities of functional assays were between 73 and 93%, while sensitivities of ELISA declined dramatically to 33%. FII/factor X and FII/factor VII + factor X ratios were significantly higher in 20210A carriers (P < 0.0001). In conclusion, functional assays are preferentially required for measurements of FII levels in carriers of the 20210A variant.

3' Untranslated Regions↗
PubMed2002

The prothrombin G20210A polymorphism in patients with myocardial infarction.

To investigate a possible association between the human prothrombin gene G20210A polymorphism and coronary artery thrombosis, we screened 172 consecutive patients with ischaemic heart disease admitted for coronary arteriography. The patients were divided into two groups on the basis of their clinical history and examination of their hospital records: 66 patients with a definite previous myocardial infarction, and 106 with angina-like chest pain but no evidence of myocardial infarction. The overall frequency of the G20210A polymorphism was 0.011, four out of the 172 patients being heterozygous for the mutation. The allelic frequency was 0.015 in the group with myocardial infarction and 0.009 in the group without myocardial infarction (P = 0.622). The results of this study suggest that the single nucleotide polymorphism at position 20210 of the prothrombin gene is unlikely to be a risk factor for coronary thrombosis.

Adult↗
PubMed1990

Predicting the daily prothrombin time response to warfarin.

Our objective was to evaluate the effectiveness of a computer program to predict daily prothrombin time (PT) response to warfarin therapy using prospectively collected data. The program's predictive performance (precision) and accuracy (bias) were evaluated using fraction mean absolute error and fraction mean error, respectively. We analyzed data from 40 patients using from zero to nine PT feedbacks. The fraction mean absolute error varied from 0.058 to 0.13. The program utilized a pharmacokinetic/pharmacodynamic Bayesian forecasting system to predict prothrombin response.

Aged↗
PubMed2002

Detection of a novel point mutation of the prothrombin gene at position 20209.

Detection of the prothrombin G20210A mutation was performed on the LightCycler Instrument (Roche Molecular Biochemicals, Mannheim, Germany) using commercially available primers and hybridization probes. Herein we report four cases from unrelated African American individuals where LightCycler analysis showed atypical melting curves. Sequence analysis of the four samples showed heterozygosity for a C to T mutation 1 bp upstream from the known 20210 mutation at position 20209. The clinical significance of this mutation is not known, but three patients in whom it was detected had a history of venous thrombosis or stroke. The fourth patient had severe liver disease, which may have masked thrombotic predisposition. Since most assays used to detect the G20210A mutation use a PCR/restriction digestion assay, which would not detect the C20209T mutation, this new mutation may be underrecognized when prothrombin gene mutation testing is performed by PCR/restriction digestion assay.

Adult↗
PubMed2003

Factor V Leiden and prothrombin gene mutation may predispose to paradoxical embolism in subjects with patent foramen ovale.

The role of paradoxical embolism through patent foramen ovale as a mechanism of cryptogenic stroke is controversial. If a venous source of emboli is relevant, prothrombotic states should be associated with patent foramen ovale and cryptogenic stroke. We assessed the occurrence of several prothrombotic states (factor V Leiden, prothrombin G20210A, deficiencies in protein S, protein C and antithrombin, lupus anticoagulant, anticardiolipin antibodies, elevated factor VIII, resistance to activated protein C) and classical risk factors for venous thrombosis in 57 adult patients with cryptogenic stroke and patent foramen ovale and in 104 matched controls. Prothrombotic states [odds ratio (OR) 2.8; 95% confidence interval (CI), 1.2-6.5; P = 0.021], migraine with aura (OR 4.4; 95% CI 1.8-10.8; P = 0.001) and classical risk factors for venous thrombosis (OR 2.5; 95% CI 1.1-5.7; P = 0.037) were independent risk factors for cryptogenic stroke. In particular factor V Leiden or prothrombin G20210A associated with cryptogenic stroke (P = 0.022) whereas other coagulation abnormalities did not (P = 0.140). Among the patients with prothrombotic states, Valsalva manoeuvre was common at onset of stroke. Our results support the possibility of paradoxical embolism behind strokes in patients with patent foramen ovale.

Adolescent↗
PubMed2006

Risk of recurrent venous thrombosis in patients with G20210A mutation in the prothrombin gene or factor V Leiden mutation.

The impact of the G20210A prothrombin mutation, factor V Leiden and 677T mutation of methylene tetrahydrofalate reductase (MTHFR) in recurrent deep venous thrombosis (DVT) is not so clear. We have prospectively monitored 259 patients following a first episode of DVT in order to determine which factors influence the development of a recurrent event. Several clinical and biological factors together with the genetic polymorphisms of factor V Leiden, G20210A prothrombin and 677T MTHFR were assessed. During a median follow-up of 786 patient-years, 27 patients (14%) developed one objective episode of recurrent venous thrombosis. The carriers of a double defect, homozygous or double heterozygous for factor V Leiden and G20210A, had an increased risk after a first episode of DVT, while patients who were isolated heterozygous for factor V Leiden or G20210 had a risk of recurrent DVT similar to patients who had neither mutation (annual incidence of 12.1, 3.1, 2.9 and 2.8%). The 677T MTHFR mutation alone or combined with hyperhomocysteinemia was not associated with an increased risk of recurrent events. The development of proximal DVT (P=0.01) and the presence of a double defect (P=0.01) were the only two risk factors independently associated with a high recurrence ratio in the multivariate analysis. Thus, the annual incidence of DVT recurrence in patients without any of these two risk factors was only 0.6% (95% confidence interval, 0.2-0.9). We have identified a group of patients with DVT but at very low risk of re-thrombosis in whom an extended secondary thromboprophylaxis should be carefully considered.

Adolescent↗
PubMed2005

Preoperative screening for coagulopathy using prothrombin time and partial thromboplastin time in patients requiring primary cranial vault remodeling.

BACKGROUND: The aim of this study was to investigate the prevalence of abnormal preoperative screening prothrombin time and partial thromboplastin time in patients listed for primary cranial vault remodeling that required hematologic workup and their diagnoses and subsequent management. METHODS: This retrospective analysis was performed from January of 2000 to December of 2003 at the International Craniofacial Institute, Dallas, Texas, on a total of 168 patients. RESULTS: All patients had a normal prothrombin time. Abnormally raised partial thromboplastin time was found in six patients (prevalence of 3.57 percent), one who had factor XI deficiency, one who had a borderline factor XI deficiency and circulating inhibitor, one who had an intermittent factor XI deficiency and circulating inhibitor, one who had a borderline von Willebrand's disease with low factor XII, and the remaining two who had a circulating inhibitor of coagulation. Of these six patients, the perioperative management was altered in four of five patients, and one patient declined surgery out of fear of surgical morbidity. The surgery of one patient was aborted intraoperatively because of abnormal bleeding without clot formation after the calvarial burr holes had been drilled. The mean blood loss was 183 ml for the four patients with completed surgery and 100 ml for one patient. CONCLUSIONS: The authors conclude that even though the prevalence of abnormal screening partial thromboplastin time in these patients was low (3.57 percent), detection of an abnormal result required preoperative correction of coagulopathy in 80 percent of cases.

Blood Coagulation Disorders↗
PubMed2003

Is screening for factor V Leiden and prothrombin G20210A mutations in renal transplantation worthwhile? Results of a large single-center U.K. study.

This single center study is the largest series of renal transplant recipients and donors screened for the commonest prothrombotic genotypes. A total of 562 transplant recipients and 457 kidney donors were genotyped for the factor V Leiden and prothrombin G20210A mutations. The prevalence of heterozygous factor V Leiden was 3.4% and 2.6% and prothrombin G20210A was 2.0% and 1.1% in recipients and donors, respectively, similar frequencies to that of the general U.K. population. The 30-day and 1-year graft survival rates in recipients with thrombophilic mutations were 93% and 93%, compared with 88% and 82% in patients without these mutations (log-rank P=0.34). Thrombophilia in recipients (odds ratio 0.55; confidence interval 0.06-2.29; P=0.56) or in donors (odds ratio 1.53; confidence interval 0.27-5.74; P=0.46) did not correlate with graft loss at 30 days after transplantation. In contrast to recent reports, this study did not demonstrate an association between thrombophilia and renal allograft loss, and routine screening is not recommended.

Adolescent↗
PubMed2005

Cloning and functional expression of venom prothrombin activator protease from Pseudonaja textilis with whole blood procoagulant activity.

The snake venom group C prothrombin activators contain a number of components that enhance the rate of prothrombin activation. The cloning and expression of full-length cDNA for one of these components, an activated factor X (factor Xa)-like protease from Pseudonaja textilis as well as the generation of functional chimeric constructs with procoagulant activity were described. The complete cDNA codes for a propeptide, light chain, activation peptide (AP) and heavy chain related in sequence to mammalian factor X. Efficient expression of the protease was achieved with constructs where the AP was deleted and the cleavage sites between the heavy and light chains modified, or where the AP was replaced with a peptide involved in insulin receptor processing. In human kidney cells (H293F) transfected with these constructs, up to 80% of the pro-form was processed to heavy and light chains. Binding of the protease to barium citrate and use of specific antibodies demonstrated that gamma-carboxylation of glutamic acid residues had occurred on the light chain in both cases, as observed in human factor Xa and the native P. textilis protease. The recombinant protease caused efficient coagulation of whole citrated blood and citrated plasma that was enhanced by the presence of Ca2+. This study identified the complete cDNA sequence of a factor Xa-like protease from P. textilis and demonstrated for the first time the expression of a recombinant form of P. textilis protease capable of blood coagulation.

Amino Acid Sequence↗
PubMed1980

Antithrombin III contribution to cholestasis differential diagnosis: its correlation with one stage prothrombin time and factor V.

Levels of antithrombin III (AT III) measured by two different methods, Factor V (FV) and One Stage Prothrombin Time, have been studied in two groups of patients: 55 with chronic liver disease and 22 with extra hepatic cholestasis. Results show a statistically significant correlation between the decrease of AT III and FV in the first group, and the normality of these parameters (unrelated to One Stage Prothrombin Time) in the second group. Levels at AT III and FV correlate directly with the functional integrity of hepatic parenchyma, so they may help in the differential diagnosis of different types of cholestasis.

Antithrombin III↗
PubMed1993

Low-dose warfarin decreases coagulability without affecting prothrombin complex activity.

OBJECTIVES: To assess the efficacy of a fixed, low dose of warfarin in lowering factor VII coagulant activity (FVII:C) and to investigate the effects on the plasma coagulation cascade. DESIGN: An open pilot study with two dose levels of warfarin: 1.25 and 2.5 mg day-1 during two consecutive 4-week periods. All subjects received aspirin 75 mg day-1. Prothrombin fragment 1 + 2 (F(1 + 2)), protein C, protein S, FVII:C, factor X and P-prothrombin complex activity (P-PT) were measured at baseline, at 2-week intervals and 4 weeks after end of treatment. Coagulation activation peptide F(1 + 2) was used as a marker of thrombin formation. SUBJECTS: Twelve male patients with a history of myocardial infarction. Inclusion was made through a written questionnaire. RESULTS: Warfarin 1.25 mg day-1 lowered FVII:C from 113 U dl-1 to 107 U dl-1 (P = 0.025) and F(1 + 2) from 1.60 nmol l-1 to 1.27 nmol l-1 (P = 0.013) but had no effect on protein C or P-PT. A dose of 2.5 mg day-1 induced further lowering of FVII:C (91 U dl-1, P = 0.0042), and also of protein C from 116% to 99% (P = 0.034) and P-PT from 107% to 81% (P = 0.0096) mean values. CONCLUSION: Warfarin 1.25 mg day-1 seems to exert an anticoagulant effect without reduction in PT or the natural anticoagulant protein C and is suggested, in combination with aspirin, to be a safe and simple therapy against arterial thrombotic disease, making regular PT controls unnecessary.

Adult↗
PubMed1992

Predicted secondary structure of bovine prothrombin fragment 1 and related proteins in different environments by circular dichroism spectroscopy.

Circular dichroism spectroscopy was used to investigate the structure of bovine prothrombin fragment 1 (BF1) and related proteins in several environments. The conformational change induced in BF1 by the addition of Mg[II] ions was found to be different from that induced by Ca[II] or Sr[II]. The Ca[II] and Sr[II] conformations appear to differ only slightly from the apo-metal conformation. The conformation of the 1-45 fragment of prothrombin, however, is markedly different than the conformation of the same fragment in the presence of either Ca[II] of Mg[II]; both of the latter structures differ substantially from one another. The presence of phospholipids has almost no effect on the structure of either BF1 or the 1-45 fragment; in the presence of both phospholipids and Ca[II] a structural change is seen for the 1-45 fragment but not BF1 (relative to the protein alone). The addition of phospholipids to the Mg[II]/BF1 structure did not induce a CD-detectable conformational change, while the addition of phospholipids to the Ca[II]/BF1 or Sr[II]/BF1 structures induced a change to a conformation similar in secondary structure composition to the relative apometal structures.

Animals↗
PubMed1988

Purification and characterization of a novel protein from bovine aorta that inhibits coagulation. Inhibition of the phospholipid-dependent factor-Xa-catalyzed prothrombin activation, through a high-affinity binding of the anticoagulant to the phospholipids.

A novel inhibitor of blood coagulation has been isolated from the intima of bovine aorta. The inhibitor, vascular anticoagulant (VAC), has been purified to an active fraction that contains two Coomassie-blue-staining bands (Mr = 34,000 and Mr = 32,000, as judged by sodium dodecyl sulfate/polyacrylamide electrophoresis). Both bands are single-chain proteins, having no glycoprotein features. Furthermore, they do not contain any detectable 4-carboxyglutamic acid residues. Both proteins have an identical isoelectric pH of approximately 4.5. VAC binds in the presence of calcium ions to a bilayer consisting of 20% dioleoylglycerophosphoserine and 80% dioleoylglycerophosphocholine with a Kd = 6 nM. The binding is dependent on the calcium concentration: half-saturation of binding occurs at a calcium concentration of 0.8 mM. The binding is completely reversible with EDTA. Furthermore the phospholipid/VAC ratio at saturation was n = 112 and n = 32 mol/mol for 0.5 mM Ca2+ and 2 mM Ca2+, respectively. Binding does not occur between VAC and pure dioleoylglycerophosphocholine. In a system with purified coagulation factors VAC inhibits the activation of prothrombin by factor Xa and calcium only in the presence of negatively charged phospholipids. VAC decreases the Vmax and increases the Km of the factor-Xa-catalyzed prothrombin activation. Based on these results, we conclude that we have purified from bovine aortic intima an anticoagulant protein, which exerts its activity through a calcium-dependent binding to negatively charged phospholipids, and thus interferes with the assembly of prothrombinase on the phospholipid surface.

Animals↗
PubMedDate not supplied

A comparison between des-gamma-carboxy prothrombin and alpha-fetoprotein as markers of hepatocellular carcinoma in southern African blacks.

Des-gamma-carboxy prothrombin (DCP), a precursor of prothrombin, has been reported recently to be as good a marker, or even better, of hepatocellular carcinoma than alpha-fetoprotein (alpha-FP). The sensitivity, specificity and predictive values of the two markers have been compared in 98 southern African Blacks with hepatocellular carcinoma and in 120 Black controls with various diseases which might be mistaken clinically for this tumour: 32 with hepatic metastases, 33 with amoebic hepatic abscesses, and 55 with chronic hepatic parenchymal disease. DCP levels were measured using a chromogenic assay with Dispholidus typus venom and staphylocoagulase. The agreement between the two methods was excellent (r = 0.995). alpha-FP concentrations were measured by radioimmunoassay. DCP levels were raised in 66 of 98 patients (67.3%) and alpha-FP levels in 82 of 98 patients (83.7%) with hepatocellular carcinoma (P = 0.006). The specificity of DCP was also less than that of alpha-FP, although the difference just failed to reach statistical significance (P = 0.085). The predictive values of both a positive and a negative test for DCP were significantly less than those for alpha-FP (P = 0.047 and 0.048, respectively). When, in an attempt to eliminate false positive results, the diagnostic cut-off level for DCP was increased from 1.5 to 5.0 mu/ml and that of alpha-FP from 20 to 400 ng/ml, the differences between the two markers remained the same. If the two tests were used together, the number of false negative alpha-FP results was reduced from 16.3% to 7.1% and the number of equivocal alpha-FP results was reduced from 11.2% to 5.1%.(ABSTRACT TRUNCATED AT 250 WORDS)

Biomarkers↗
PubMed1977

The use of non-activated prothrombin concentrate in the management of haemophilia A with factor VIII antibodies.

Three children with haemophilia and antibodies to factor VIII were treated with a non-activated prothrombin concentrate (Prothrombinex) for 12 bleeding episodes. There was clear clinical response and joint aspirations were performed after infusions of phothrombinex in a dose of 30--50 factor IX units/kg body weight and there was no clinical evidence of thrombosis or febrile reactions. There was a significant shortening of the activated partial thromboplastin time (PTT) at one and four hours after the initial infusion with a return to pre-infusion levels 9--24 hours after infusion. The shortening in the PTT was less marked in subsequent infusions. There were no changes in the level of factor VIII procoagulant activity, factor VIII related antigen or factor VIII antibodies after the infusion. In two patients platelet function studies were unaltered by the infusion and in one patient procoagulant levels of factor II, IX and X were no greater than expected from the infusion. We conclude that infusions of non-activated prothrombin concentrates are clinically effective in the treatment of children with haemophilia and factor VIII antibodies but the mechanism of action is unknown.

Adolescent↗