Prothrombin A19911G and G20210A polymorphisms' role in thrombosis

The prothrombin G20210A polymorphism, which correlates with the plasmatic prothombin levels, is the second genetic risk factor for deep venous thrombosis (DVT), although its prothrombotic role is mild. Recently, the prothrombin A19911G polymorphism, also associated with slight variations of the prothrombin level, has been suggested to modulate the thrombotic risk of the G20210A polymorphism in a preliminary study including few patients and controls. Our study evaluated the effect of the A19911G polymorphism in the arterial and venous thrombotic risk of the prothrombin 20210G/A genotype, analysing 204 consecutive DVT patients and 204 matched controls. Moreover, we analysed 213 carriers of the 20210G/A genotype (152 with DVT, 26 with arterial thrombosis and 35 healthy subjects) and 10 homozygous 20210 A/A carriers. We developed a simple method to simultaneously determine the genotype of both polymorphisms. In accordance with our case/control study, the A19911G polymorphism did not play a significant role in the development of DVT. Analysis of 120 20210 A alleles demonstrated a complete linkage disequilibrium with the 19911 A allele. These polymorphisms (alone or combined) did not modify the risk of arterial thrombosis. However, the 19911A/G genotype slightly increased the risk of developing DVT in carriers of the 20210G/A genotype (OR 3.34 vs 5.86), supporting that the prothrombin 19911 polymorphism could modulate the risk of the G20210A polymorphism in developing DVT.     

Prothrombin G20210A gene mutation and further prothrombotic risk factors in childhood thrombophilia.

Risk factors for venous thrombosis in adults are the prothrombin G20210A and the factor V (FV) G1691A mutations and hereditary deficiencies of protein C, protein S and antithrombin. However, data are limited on the relevance of these risk factors for thrombosis in children and adolescents. We therefore investigated 261 patients aged 0 to 18 (median 5.7 years, 48% male) with venous thrombosis and controls (n=370) for the presence of prothrombotic risk factors including the prothrombin G20210A mutation. The following frequencies of hereditary risk factors (patients versus controls), odds ratios (OR) and 95% confidence intervals (CI), or results of Fisher's exact test, respectively, were found: prothrombin G20210A, 4.2% versus 1.1%, OR/CI 4.1/1.3 to 12.8; FV G1691A, 31.8% versus 4. 1%, OR/CI 11.0/6.2 to 19.7; protein C deficiency, 9.2% versus 0.8%, OR/CI 12.4/3.7 to 41.6, protein S deficiency, 5.7% versus 0.8%, OR/CI 7.5/2.1 to 26.0; antithrombin deficiency in 3.4% in the patients, but not in the controls, P=0.0003. The prothrombin mutation was combined with the heterozygous FV G1691A mutation (2. 3%) or protein C deficiency (0.3%) in the patients, but not in the controls (prothrombin and FV mutation, P=0.0048; prothrombin and protein C deficiency, not significant). The carrier frequencies and ORs of all hereditary risk factors showed a non-significant trend toward higher prevalences in patients suffering spontaneous thrombosis, compared with those with an additional underlying disease. In conclusion, the prothrombin G20210A and the FV G1691A mutation, deficiencies of protein C, protein S, and antithrombin are important risk factors for venous thrombosis during childhood and adolescence.     

Prothrombin G20210A gene mutation with LightCycler polymerase chain reaction in venous thrombosis and healthy population in the southeast of Turkey

Venous thrombosis (VT) is a common disease, with an annual incidence in the general population of approximately 1 per 1000. The prevalence of genetic risk factors for thrombosis varies greatly in different parts of the world. Prothrombin G20210A (PT G20210A) gene mutation has been recently identified as a common risk factor in venous thrombosis. Sixty-one patients with VT, differing in age and sex, and 340 healthy subjects were consecutively enrolled into our study to determine the prevalence of PT G20210A in VT and in the healthy population of the southeast of Turkey. The mutation was identified with fluorescence resonance energy transfer (FRET) with the LightCycler polymerase chain reaction. The PT G20210A mutation was found to be 6.5% (4/61) in the VT group and 1.2% (4/340) in the healthy group (P = 0.021). Three patients with VT had a heterozygous PT G20210A mutation, and the other patient with VT had both Factor V Leiden and PT G20210A mutations. We showed that this method may be used safely for detection of the PT G20210A gene mutation, and the prevalence of PT G20210A mutation is significantly higher in patients with VT than in the healthy population in the southeast of Turkey.     

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.     

Prothrombin G20210A gene mutation, heparin cofactor II defects, primary (essential) thrombocythemia, and thrombohemorrhagic manifestations.

This article addresses the issue of thromboembolic disorders associated with the prothrombin G20210A gene mutation, with heparin cofactor II (HC-II) defects and with primary (essential) thrombocythemia. The prothrombin gene mutation is of recent discovery, is inherited as an autosomal dominant disorder, and seems to be highly prevalent in the general white population. The incidence is almost as high as that known for factor V Leiden. Both venous and arterial thromboses are noted, especially deep venous thrombosis, including cerebral venous events and myocardial infarction. As with other congenital thrombophilic states, additional risk factors or multiple defects seem to precipitate the events. Although initially elevated plasma prothrombin levels were described in these patients, this is no longer valid for all patients. At this time there is no easy screening test to detect this defect, but, because of the high prevalence, prothrombin G20210A gene mutation should routinely be assayed for in thrombophilic patients. The association between HC-II defects and thromboembolism is more controversial, and reports both confirming and denying this association have been described. The congenital form of HC-II defect is autosomal dominant. HC-II can be determined by its activity and immunologically. HC-II defects very likely play a role in conjunction with other congenital or acquired defects. Acquired HC-II defects are found in association with systemic disseminated intravascular coagulation (DIC) but not with local activation of the hemostasis system. HC-II levels are also decreased in preeclamptic women, and newborns have physiologically low levels. HC-II defects in thrombophilic patients should be considered after the more common disorders have been ruled out. Primary (essential) thrombocythemia can be associated with both thromboembolic events and bleeding. Typical thrombotic manifestations are erythromelalgia and microvascular thrombosis. Also, pregnant females suffer high rates of complications, such as spontaneous abortion. A number of treatment modalities are at present available to not only decrease platelet counts but also manage thromboembolic events.     

Factor V Leiden,prothrombin gene mutation,and thrombosis risk in patients with antiphospholipid antibodies

OBJECTIVE: To determine if the prevalence of 2 prothrombotic genetic factors, factor V Leiden and prothrombin gene mutation, is increased in patients with antiphospholipid (aPL) antibodies with a history of venous/arterial thrombosis compared to patients with aPL antibodies with no history of thrombosis. METHODS: One hundred fifty-seven patients with aPL antibodies were studied. The occurrence of venous and arterial thrombotic events since the time of antibody detection was determined retrospectively, using appropriate clinical and diagnostic criteria. Clinical risk factors for thrombosis were documented and included hypertension, hyperlipidemia, cigarette smoking, diabetes, positive family history, use of oral contraceptive, pregnancy, trauma, hospitalization, varicose veins, and malignancy. Genomic DNA was extracted from blood cells for determination of factor V Leiden mutation G1691 --> A and prothrombin mutation G20210 --> A by polymerase chain reaction and restriction fragment length polymorphism analysis. RESULTS: Of 157 patients, 69 had a history of thrombosis (venous 37, arterial 32); 147 (94%) patients had anticardiolipin (aCL) antibodies; 69 (45%) had lupus anticoagulant (LAC). The prevalence of factor V Leiden in patients with thrombosis was 13% compared to 4.6% in patients without thrombosis (OR 3.11, CI 0.92-10.6). In patients with aCL antibodies, 15% of patients with arterial thrombosis had factor V mutation compared to 3.5% of patients without thrombosis (OR 4.9, CI 1.2-19.3). The prothrombin gene mutation was identified in 5 patients, none of whom had thrombosis. Stepwise logistic regression analysis indicated that LAC (p = 0.005), male sex (p = 0.04), and hypertension (p = 0.03) were the strongest risk factors for developing thrombosis and that no additional risk was conferred by factor V Leiden (p = 0.13) and prothrombin gene mutation. CONCLUSION: Although the prevalence of factor V Leiden is modestly increased in patients with autoimmune aPL antibodies and thrombosis, these results suggest that its detection does not significantly increase the risk of a thrombotic event, once other clinical risk factors have been considered. Prothrombin gene mutation is not associated with thrombosis in patients with aPL antibodies.     

20210G/A mutation of prothrombin gene in a patient with deep venous thrombosis ad pulmonary embolism without other risk factors of thrombosis

A new genetic anomaly predisposing to venous thrombosis was described in 1996, namely the transition of guanine (G) to adenine (A) at position 20210 in the 3-untranslated region of the prothrombin gene. This mutation is associated with high levels of plasma prothrombin and increased risk of thrombotic events in the venous system. We report the case of a man who, lacking known risk factors for thrombosis, suffered a massive pulmonary embolism and deep venous thrombosis in both lower legs. Thrombophilic analysis confirmed that the patient and close relatives were carriers of the heterozygotic 20210G/A variant of the prothrombin gene. Two relatives with the genetic defect had also suffered some type of deep venous thrombosis.     

Prothrombin G20210A gene variant is not associated with idiopathic portal vein thrombosis in an area endemic for portal vein thrombosis

Prothrombin G20210A gene variant has been found in 0–23% of patients with portal vein thrombosis (PVT). This wide variation makes it difficult to assess the importance of prothrombin G20210A gene variant as a predisposing factor for PVT. In this study from South India, none of the patients with idiopathic PVT (0/38) or any of the controls (0/46) had prothrombin G20210A gene variant. Prothrombin G20210A gene variant does not contribute to the development of PVT in India.     

Prothrombin and the prothrombin 20210 G to A polymorphism: their relationship with hypercoagulability and thrombosis

Polymorphisms of several clotting factors have been associated during the past few years with an increased risk of both venous or arterial thrombosis. However, final proof for the existence of a pathogenetic relationship between a given polymorphism and an increased risk for thrombosis is still lacking. Particular emphasis has been placed recently on a 20210 G to A prothrombin polymorphism. A critical review of available data indicates that such an abnormality may be associated with an increased risk of venous thrombosis but not arterial thrombosis (with a possible exception for myocardial infarction). However, this conclusion is based only on retrospective cohort studies which compared the prevalence of the abnormality in a group of patients with past venous or arterial thrombosis with a normal group (with no thrombosis). No prospective study has yet to show that patients with the abnormality, given similar additional acquired risk factors, have a higher incidence of thrombotic complications as compared with controls. The mechanism whereby the abnormality might cause thrombosis has been assumed to be an increase in prothrombin levels. Since an association between two phenomena does not necessarily mean that a causal relationship exists between the same events, it is important to be cautious before claiming that such abnormality is responsible for thrombosis. Therefore, although included commonly in the investigation profile, the search for the 20210 G to A prothrombin abnormality should not be considered yet to be an essential component in the routine study of hypercoagulable and/or thrombotic conditions.     

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.     

Portal vein thrombosis associated with a myeloproliferative disorder, prothrombin G20210A mutation, antiphospholipid syndrome, with repermeation during anticoagulant therapy

Portal vein thrombosis, except in hepatocellular carcinoma and severe cirrhosis, is due to one or several prothrombotic disorders with or without a local precipitating factor. We report a case of a portal and splenic vein thrombosis, without cavernoma and varices which occurred in a 72-year-old man with abdominal pain and weakness. Three prothrombotic states including latent myeloproliferative disorder, antiphospholipid syndrome, and factor II G202101 mutation, were observed. Anticoagulant treatment resulted in complete repermeation of the portal and splenic veins without a hemorrhagic event. This illustrates that several prothrombotic states may occur in a single patient with portal vein thrombosis. Early anticoagulant therapy, in recent portal vein thrombosis, can result in repermeation.     

Heterozygous prothrombin gene mutation G20210A and associated diseases

PURPOSE: Prothrombin gene mutation G20210A (factor II) is, in frequency, the second genetic polymorphism involved in venous thrombosis. We report a retrospective studies on 38 patients issued from our medical department, all heterozygous for the factor II mutation and a literature review. METHODS: We have studied 38 patients, all heterozygous for the factor II mutation, selected through a population of 516 tested patients issued from our medical department from 1997 to 2002. The research was performed face with history of thrombotic or obstetrical events, angiopathy or familial screening. RESULTS: Twenty out of thirty-eight patients have at least one episode of venous thrombosis: superficial thromboses, deep thromboses and/or pulmonary embolism. One case of cerebral thrombophlebitis is observed. Venous thrombotic risk factors are associated in 12 cases (60%). Four out of thirty-eight patients have one episode of arterial thrombosis: cardiovascular, peripheral or cerebral. Arterial thrombotic risk factors are associated in all cases. Median age of the first venous thrombosis is earlier than the one of arterial thrombosis (39.11 versus 49.25 years). CONCLUSION: Our studies confirms the interest to search the prothrombin gene mutation when faced with a venous thrombotic event (deep vein thrombosis and/or pulmonary embolism) with or without acquired risk factors. Its involvement in thrombotic arterial disease is still a matter of debate. Data concerning its involvement in systemic diseases and angiopathies (thromboangeitis obliterans, Raynaud's phenomenon and migraine) are still needed. Mechanisms of thromboses could be an increase of prothrombin plasma level with high thrombin synthesis.     

G20210A Prothrombin gene variant in Turkish patients with angiographically documented coronary artery disease

Background G→A substitution at position 20210A in the 3′-untranslated region in prothrombin gene is associated with raised plasma prothrombin. G20210A prothrombin variant has been associated with high prothrombin levels and an increased risk of venous thrombosis. To determine the prevalence of the G20210A prothrombin variant among Turkish and to evaluate the potential relevance of this variant to Turkish patients with angiographically documented coronary artery disease (CAD). Methods We conducted a case-control study on 268 unrelated subjects who referred to the cardiology department of the university hospital for coronary angiography. One hundred-thirty seven patients with angiographically documented CAD and 131 subjects without angiographically documented CAD were studied to examine the association of the G20210A prothrombin variant with CAD. Blood samples from the patients and controls were analyzed for the G20210A prothrombin variant by DNA analysis, using polimeraz chain reaction. Results G20210A prothrombin variant was found in 6 of 137 (4.4%) patients with CAD and 1 of 131 (0.8%) in control subjects (p = 0.064). There were no significant differences in terms of diabetes mellitus, hypertension, dyslipidemia, sex and family history of CAD with and without the G20210A prothrombin variant in the patient group. Conclusions In agreement with the results of recent meta-analyses, our data from northeast Anatolia show a 5-fold higher prevalence of the G20210A prothrombin variant among the patients with angiographically-documented CAD when compared with those without angiographic signs of significant CAD and its variant cannot be considered as a risk factor for CAD in this region.     

Interaction between the G20210A mutation of the prothrombin gene and oral contraceptive use in deep vein thrombosis

Single-point mutations in the gene coding for prothrombin (factor II:A20210) or factor V (factor V:A1691) are associated with an increased risk of venous thromboembolism. The use of oral contraceptives is also a strong and independent risk factor for the disease, and the interaction between factor V:A1691 and oral contraceptives greatly increases the risk. No information is available about the interaction between oral contraceptives and mutant prothrombin. We investigated 148 women with a first, objectively confirmed episode of deep vein thrombosis and 277 healthy women as controls. Fourteen patients (9.4%) were carriers of factor II:A20210, 24 (16.2%) of factor V:A1691, and 4 (2.7%) of both defects. Among controls, the prevalence was 2.5% for either factor II:A20210 or factor V:A1691, and there was no carrier of both the mutations. The relative risk of thrombosis was 6-fold for factor II:A20210 and 9-fold for factor V:A1691. The most prevalent circumstantial risk factor in patients and the only one observed in controls was oral contraceptive use, which per se conferred a 6-fold increased risk of thrombosis. The risk increased to 16.3 and 20.0 when women with factor II:A20210 or factor V:A1691 who used oral contraceptives were compared with noncarriers and nonusers. These figures indicate a multiplicative interaction between the genetic risk factors and oral contraceptives. No difference in the type of oral contraceptives was observed between patients and controls, those of third generation being the most frequently used (73% and 80%). We conclude that carriers of the prothrombin mutation who use oral contraceptives have a markedly increased risk of deep vein thrombosis, much higher than the risk conferred by either factor alone.     

Factor V Leiden, prothrombin G20210A, and protein C mutation frequency in Turkish venous thrombosis patients

Several inherited polymorphisms are associated with risk of venous thrombosis, including mutation at codon 506 of the factor V gene, mutation at position 20210 of the prothrombin gene, and mutations in the protein C gene. In this study, genotyping for factor V, prothrombin, and protein C mutations was performed in 50 patients and 25 control subjects by polymerase chain reaction-based analysis. The prevalence of factor V and prothrombin mutations was not significantly different from that in the general population. Nine of the patients had heterozygous protein C mutation. There was a high prevalence of the mutated protein C allele in the pulmonary emboli group (42.8%). Protein C mutation incidence was higher in the pulmonary emboli group than in the deep vein thrombosis (8.33%) and cerebral vein thrombosis (16.1%) groups. These results indicate that patients with protein C deficiency have a greater risk of thrombosis than patients with factor V or prothrombin G20210A mutation.