The VITA Project: Prothrombin G20210A Mutation and Venous Thromboembolism in the General Population

Pediatric Thromboembolism in Japan

OBJECTIVES

To investigate the clinical and epidemiologic characteristics of thromboembolism in Japanese children.

METHODS

Clinical data of 77 patients with thromboembolism from a national tertiary pediatric care center were reviewed.

RESULTS

Incidence of thromboembolism was calculated to be 15 per 10,000 hospital admissions. Infants younger than one year of age made up the largest age group (25 patients, including nine neonates younger than 30 d). The occurrence of thromboembolism increased over the years in the index population. Thromboembolism was diagnosed as follows: portal vein thrombosis (n = 15), obstruction of central venous catheter (n = 13) and cerebral infarction (n = 9). Among the 77 patients, there were eight mortalities and six significant sequelae.

CONCLUSIONS

In pediatric care, especially in intensive care, we should pay more attention to thromboembolism in order to detect it promptly.

Lack of Association between Inherited Thrombophilic Risk Factors and Idiopathic Sudden Sensorineural Hearing Loss in Italian Patients

Objectives:

We investigated the presence of congenital thrombophilic risk factors in a population of consecutive Italian patients affected by idiopathic sudden sensorineural hearing loss (SSNHL).

Methods:

We investigated 48 patients with idiopathic SSNHL for the presence of congenital thrombophilic risk factors. The factor V Leiden G1691A, the prothrombin G20210A allele, and methylenetetrahydrofolate reductase (MTHFR) C677T genotypes were investigated. Allele frequencies and genotype distribution of all factors found in patients were compared to those of 48 healthy subjects of the same ethnic background by χ2 and odds-ratio analysis. Odds ratios and 95% confidence intervals were calculated for allele and genotype frequencies of all thrombophilia variants. Statistical significance was accepted with a p value of less than .05. We also performed the following blood tests: hemacytometric analysis including platelet count, prothrombin time, activated partial thromboplastin time, fibrinogen, erythrocyte sedimentation rate, C-reactive protein, protein S, protein C, antithrombin III, and activated protein C resistance.

Results:

In our series, we did not find an association between SSNHL and abnormal levels of antithrombin III, protein C, protein S, D-dimer, or fibrinogen; activated protein C resistance; or factor V G1691 A, prothrombin G20210A, or MTHFR C677T mutations.

Conclusions:

At present, the few studies regarding genetic polymorphisms of congenital thrombophilic factors in SSNHL are not conclusive. According to our data, factor V G1691A, prothrombin G20210A, and MTHFR C677T variants should be not considered risk factors for SSNHL. Further large prospective studies are needed to provide currently lacking information and to improve our knowledge in the field before we recommend the determination of genetic polymorphism in SSNHL as routine practice.

Diagnosis and management of cerebral venous thrombosis: a statement for healthcare professionals from the American Heart Association/American Stroke Association

BACKGROUND

The purpose of this statement is to provide an overview of cerebral venous sinus thrombosis and to provide recommendations for its diagnosis, management, and treatment. The intended audience is physicians and other healthcare providers who are responsible for the diagnosis and management of patients with cerebral venous sinus thrombosis.

METHODS AND RESULTS

Members of the panel were appointed by the American Heart Association Stroke Council's Scientific Statement Oversight Committee and represent different areas of expertise. The panel reviewed the relevant literature with an emphasis on reports published since 1966 and used the American Heart Association levels-of-evidence grading algorithm to rate the evidence and to make recommendations. After approval of the statement by the panel, it underwent peer review and approval by the American Heart Association Science Advisory and Coordinating Committee.

CONCLUSIONS

Evidence-based recommendations are provided for the diagnosis, management, and prevention of recurrence of cerebral venous thrombosis. Recommendations on the evaluation and management of cerebral venous thrombosis during pregnancy and in the pediatric population are provided. Considerations for the management of clinical complications (seizures, hydrocephalus, intracranial hypertension, and neurological deterioration) are also summarized. An algorithm for diagnosis and management of patients with cerebral venous sinus thrombosis is described.

Hereditary Thrombophilic Risk Factors and Venous Thromboembolism in Istanbul, Turkey: The Role in Different Clinical Manifestations of Venous Thromboembolism

The aim of this study was to investigate the hereditary thrombophilic risk factors in patients with venous thromboembolism (VTE) and whether these risk factors play a different role in patients with isolated pulmonary embolism (PE) as compared with patients with deep vein thrombosis (DVT) and patients with PE + DVT. The protein C (PC), protein S, antithrombin activities, homocysteine levels, and factor V Leiden (FVL) G1691A and prothrombin G20210A mutations were evaluated in 191 patients with VTE and 191 controls. The prevalence of FVL and PC deficiency were higher in patients ( P = .003 and P = .02, respectively). There was no significant difference for the other risk factors. The combination of thrombophilic risk factors was significantly higher in patients with DVT + PE as compared with patients with isolated PE or DVT ( P = .04). In conclusion, the most important hereditary risk factors for VTE in this study were the FVL mutation and PC deficiency.

Renal vascular sclerosis is associated with inherited thrombophilias

Vascular sclerosis is often seen in renal biopsies. It is usually associated with diabetes mellitus, hypertension, smoking, etc. However, whether inherited thrombophilic states such as factor V gene mutation, prothrombin gene mutation, and methylenetetrahydrofolate reductase (MTHFR) gene mutation are associated with the vascular sclerosis is not known. Renal biopsies that showed vascular disease were grouped into five groups: (1) diabetic patients, (2) hypertensive patients, (3) diabetic and hypertensive patients, (4) smokers, and (5) vascular sclerosis of unknown etiology (idiopathic renal disease). Renal biopsies with no vascular sclerosis were used as controls. Frozen tissue was analyzed for factor V Leiden mutation, prothrombin G20210A mutation, and MTHFR C677T. Factor V Leiden mutation and prothrombin G20210A mutation was not seen in patients with diabetes, hypertension, or smoking, whereas MTHFR C677T polymorphism in these groups was not significant, compared to the controls. In the idiopathic renal disease group, three of the 17 patients (17.6%) had prothrombin G20210A mutation, two of the 17 patients (11.8%) had the factor V Leiden mutation, and five of the 17 (29.4%) were homozygous for the MTHFR C677T polymorphism. When the data were evaluated as a whole, 10 mutations were found in 17 patients (P<0.0005 compared to controls) or eight of the 17 patients (47%) were observed to have at least one of the three forms of inherited thrombophilia (P<0.001 compared to controls). These findings indicate that renal vascular lesions, in the absence of diabetes, hypertension, or smoking appears to be associated with inherited thrombophilias.

Sequence variations within the genes related to hemostatic imbalance and their impact on coronary artery disease in Turkish population

Coronary artery disease (CAD) is reported to be associated with some genetic risk factors. Since identification of genetic risk factors for CAD in different ethnic groups is important for the development of new intervention and prevention programs, we investigated the association between the R353Q and -323ins10 polymorphisms in Factor VII gene, C677T mutation in MTHFR, Factor V Leiden and PT G20210A mutations and CAD in Turkish population. The promoter region of the PAI-1 gene was also screened by SSCA (single-stranded conformation analysis) using specifically designed primers. 137 CAD patients with early onset documented by coronary angiography and 41 individuals who had no significant coronary stenosis by angiography as control group were screened for the identification of the polymorphisms. In conclusion, Factor V Leiden was found to be an independent genetic risk factor for CAD in Turkish population. Combined risk assessment indicated that the coexistence of two other inherited thrombophilia markers, namely MTHFR C677T and PT G20210A with Factor V Leiden may increase the risk of the development of the disease in this population. The results of the present study show that there is no statistically significant association between the two polymorphisms in Factor VII gene, MTHFR C677T polymorphism, PT G20210A polymorphism, 4G/5G polymorphism of PAI-1 and CAD in Turkish population.

Four-color multiplex 5' nuclease assay for the simultaneous detection of the factor V Leiden and the prothrombin G20210A mutations

We developed a real-time multiplex four-color assay for the simultaneous detection of the factor V Leiden (FVL) and prothrombin (PT) G20210A mutations in one closed tube using a single thermocycling protocol. The assay combines the power of multiplex PCR with the specificity provided by allele-specific oligonucleotide (ASO) hybridization using the 5' nuclease assay format. Human genomic DNA is prepared from whole blood with standard procedures. A 97-bp DNA sequence of the coagulation factor V gene is co-amplified with a 111-bp DNA sequence of the coagulation factor II (PT) gene using four PCR primers. In addition, the reactions included four differentially labeled ASO probes for the specific detection of the different FVL/PT G20210A genotypes. To evaluate the assay's performance characteristics, we performed a comparison of two methods. We analyzed DNA samples from 52 individuals with known FVL/PT G20210A genotypes that were previously genotyped with an assay that combined PCR with the use of restriction fragment length polymorphisms. We found a 100% concordance between the results generated by both methodologies. We conclude that the four-color multiplex assay is specific and reproducible for the detection of the FVL/PT G20210A mutations, and it can be easily adapted for the detection of other SNPs.

Intraindividual consistency of the activated protein C resistance phenotype

Resistance to activated protein C (APC) has been demonstrated to be a risk factor for venous thromboembolism, but it is not known whether this phenotype is consistent over time. We reinvestigated 2580 subjects from the Vicenza Thrombophilia and Atherosclerosis (VITA) Project to evaluate the prevalence of a consistent APC resistance phenotype in the population. Among the 433 subjects with an APC resistance at first visit, the phenotype was confirmed in all the 74 factor V (FV) Leiden carriers and in 124 of 359 FV Leiden negative subjects (34%). The prevalence of a confirmed phenotype, not associated with FV Leiden, was 4.8% in our population. In a subgroup of subjects previously investigated for heritability of the APC resistance, we confirmed the APC resistance phenotype in seven of 39 (17.9%) subjects with an APC resistant sibling but only in 20 of 408 (4.9%) subjects without a sibling with the same phenotype (P = 0.005). Among the 124 FV Leiden negative subjects with a persistent APC resistance phenotype, 40 (32%) had a plasma factor VIII coagulant activity level above 150 IU/dl and eight (6.4%) were carriers of the G20210A prothrombin allele. APC resistance not due to FV Leiden is a frequent and consistent phenotype in the general population, with a possibly strong genetic influence.

Polymorphisms in coagulation factor genes and their impact on arterial and venous thrombosis

Arterial and venous thromboses, with their clinical manifestations such as stroke, myocardial infarction (MI), or pulmonary embolism, are the major causes of death in developed countries. Several studies in twins and siblings have shown that genetic factors contribute significantly to the development of these diseases. Since the advent of molecular genetics in medicine, it has been a focus of interest to elucidate the role of mutations in various candidate genes and their impact on hemostatic disorders such as arterial and venous thromboses. In this article, we review the current knowledge of the contribution of polymorphisms in coagulation factors to the development of thrombotic diseases. We show that in arterial thrombosis, results are controversial. Only for factor XIII 34Leu a protective effect on the development of myocardial infarction has been demonstrated in several studies. No other single polymorphism in a coagulation factor could be confirmed as a relevant risk factor, although there is evidence for a role of factor V Arg506Gln, factor VII Arg353Gln, and vWF Thr789Ala polymorphisms in patient subgroups. Further studies will be necessary to confirm the value of testing for genetic polymorphisms in arterial thrombosis. A large body of data is available on the role of factor V Arg506Gln and the prothrombin G20210A mutation in venous thrombosis. Some papers already recommend diagnosis and treatment strategies. We will discuss these recent publications on venous thrombosis in our review.

Prospective study of the G20210A polymorphism in the prothrombin gene, plasma prothrombin concentration, and incidence of venous thromboembolism

Case-control studies have indicated increased risk of venous thrombosis associated with the prothrombin gene G20210A polymorphism and with elevated plasma prothrombin levels. We sought to confirm these results in a prospective population-based study of 21,690 persons. We measured G20210A and prothrombin antigen on pre-event blood samples of 302 participants who developed venous thromboembolism (VTE) and 626 participants who remained free of VTE. Approximately 4.0% of cases and 2.4% of controls carried the G20210A polymorphism, but only one of 137 African Americans did. The odds ratio in whites was 1.87 (95% CI = 0.85, 4.11)--higher for those who reported a prior history of VTE (OR = 5.44) than those reporting no VTE history (OR = 1.41) and in those with idiopathic VTE (OR = 2.51) than those with secondary VTE (OR = 1.38). There was no association between venous thromboembolism and plasma prothrombin antigen level. We estimated that the G20210A polymorphism may account for approximately 2.5% of venous thromboembolism events in United States whites.

Risk factors for thromboembolism in teens: when should I test?

The discoveries of the factor V Leiden mutation and the prothrombin gene variant 20210 in the last decade have markedly contributed to the understanding of the molecular pathophysiology of inherited risk factors for thrombophilia. Population studies in the adult literature have shown that although the overall prevalence of these defects is low, affected individuals are at increased risk of thrombosis particularly if acquired risk factors for thrombosis are also present. The use of combined hormonal oral contraceptive pills is a well-known acquired risk factor, and recent studies have shown significant increased risk of thrombosis for women who carry the factor V Leiden mutation and use oral contraceptive pills. Despite this significant increased risk, mass screening of asymptomatic women for factor V Leiden prior to prescribing oral contraceptive pills is not a cost-effective use of health care dollars and could result in unnecessarily preventing many women from the contraceptive and noncontraceptive benefits of this medication. Instead, clinicians can use thoughtful screening questions to identify potentially high-risk patients for thrombophilia and consider testing for inherited risk factors on a case-specific basis.

The prevalence of thrombophilia in patients with chronic venous leg ulceration

BACKGROUND

Thrombophilia is increasingly recognized as a risk factor for deep venous thrombosis (DVT), which in turn is a major risk factor for chronic venous ulceration (CVU). However, the relationship between thrombophilia and CVU remains unknown. The aim of this study was to define the prevalence of thrombophilia in patients with CVU and to determine whether this is associated with a history or duplex scan evidence of DVT.

METHODS

Eighty-eight patients with CVU were prospectively studied. The patients underwent clinical assessment and duplex ultrasound scanning. Blood was drawn for antithrombin, proteins C and S, activated protein C resistance, factor V Leiden, prothrombin 20210A, lupus anticoagulant, and anticardiolipin antibodies.

RESULTS

The study included 35 men with a median age of 61 years (interquartile range, 45 to 72 years) and 53 women with a median age of 76 years (interquartile range, 69 to 82 years). Thirty-six percent of the patients had either a history or duplex scan evidence suggestive of previous DVT. The following abnormalities were detected: four, five, and six cases of antithrombin, protein C, and protein S deficiencies, respectively; 14 cases of activated protein C resistance; 11 cases of factor V Leiden mutation; three cases of prothrombin 20210A mutation; eight cases of lupus anticoagulant; and 12 cases of anticardiolipin antibodies. Thrombophilia was not significantly related to previous DVT, deep reflux, or disease severity.

CONCLUSION

Patients with CVU have a 41% prevalence rate of thrombophilia. This rate is two to 30 times higher than the rate of the general population but is similar to that reported for patients with previous DVT. However, in patients with CVU, thrombophilia does not appear to be related to a history of DVT, a pattern of reflux, or severity of disease. Many patients with CVU may have unsuspected postthrombotic disease.

Recurrent pulmonary embolism in a 13-year-old male homozygous for the prothrombin G20210A mutation combined with protein S deficiency and increased lipoprotein (a)

We report the case of a 13-year-old male presenting with recurrent symptoms of respiratory distress after a trauma of the lower limb. Pulmonary symptoms had been misinterpreted for several weeks and only marked symptoms of deep venous (DVT) and caval vein thrombosis later prompted the correct diagnosis of DVT and embolic events and subsequently a successful thrombolytic therapy. The case reported here shows a diagnostic pitfall of pulmonary embolism in an adolescent. It emphasizes the need to consider the possibility of thromboembolic events also in young children and adolescents presenting with atypical pulmonary symptoms and suffering from pulmonary diseases not responding to antibiotic therapy. In addition, although the homozygous PT A20210A gene mutation is a rare defect and its relevance as a risk factor on its own remains to be elucidated, this case suggests that a complete thrombophilia laboratory workup should be performed in young patients with a first symptomatic thromboembolic onset.

Cerebrovascular events in patients with significant stenosis of the carotid artery are associated with hyperhomocysteinemia and platelet antigen-1 (Leu33Pro) polymorphism

BACKGROUND AND PURPOSE

Although risk factors for carotid artery stenosis caused by atherosclerosis are known, it is unclear what triggers "activation" of the atherosclerotic plaques and the ensuing thromboembolic cerebral events. The aim of this study was to evaluate whether thrombophilic factors, platelet glycoprotein (GP) polymorphisms, and homocysteine are associated with a risk of ischemic events in patients with significant carotid stenosis.

METHODS

Consecutive patients with >/=50% carotid stenosis, whether symptomatic (with ipsilateral ischemic events) or asymptomatic, who were evaluated and followed in a neurovascular clinic were tested for plasma levels of homocysteine, C677T mutation in methylenetetrahydrofolate reductase, G20210A mutation of factor II, factor V Leiden, antiphospholipid antibodies, and polymorphisms of platelet membrane GP: human platelet antigen (HPA)-1, GP Ia (C807T), and GP Ib (variable number of tandem repeats, Kozak, and HPA-2).

RESULTS

Eighty-six asymptomatic and 67 symptomatic patients were evaluated. The former group was older (73.7+/-6.9 versus 69.5+/-9.1 years, P=0.02). Major risk factors for stroke were similar in both groups. In symptomatic patients versus asymptomatic patients, hyperhomocysteinemia was 3-fold more frequent (34.3% versus 12.8%, respectively; P=0.002) and HPA-1a/b was almost 2-fold more common (38.8% versus 20.9%, respectively; P=0.01). All other thrombophilic factors and platelet polymorphisms studied did not differ significantly between the 2 groups. Multivariate analysis revealed that hyperhomocysteinemia and the HPA-1a/b genotype conferred a significant risk of cerebral ischemic events, with odds ratios (95% CI) of 4.07 (1.7 to 9.7) and 3.4 (1.5 to 7.8), respectively.

CONCLUSIONS

Hyperhomocysteinemia and HPA-1a/b are independent risk factors for ischemic events in patients with significant carotid stenosis.

Increased efficiency of mRNA 3' end formation: a new genetic mechanism contributing to hereditary thrombophilia

The G-->A mutation at position 20210 of the prothrombin or coagulation factor II gene (F2) represents a common genetic risk factor for the occurrence of thromboembolic events. This mutation affects the 3'-terminal nucleotide of the 3' untranslated region (UTR) of the mRNA and causes elevated prothrombin plasma concentrations by an unknown mechanism. Here, we show that the mutation does not affect the amount of pre-mRNA, the site of 3' end cleavage or the length of the poly(A) tail of the mature mRNA. Rather, we demonstrate that the physiological F2 3' end cleavage signal is inefficient and that F2 20210 G-->A represents a gain-of-function mutation, causing increased cleavage site recognition, increased 3' end processing and increased mRNA accumulation and protein synthesis. Enhanced mRNA 3' end formation efficiency emerges as a novel principle causing a genetic disorder and explains the role of the F2 20210 G-->A mutation in the pathogenesis of thrombophilia. This work also illustrates the pathophysiologic importance of quantitatively minor aberrations of RNA metabolism.

Factors V leiden and II 20210A in patients with symptomatic pulmonary embolism and deep vein thrombosis

PURPOSE

Factor V Leiden and factor II 20210A are inherited disorders of the clotting system that occur frequently in patients with deep vein thrombosis. We conducted this study to determine whether these factors are also common in patients with pulmonary embolism.

SUBJECTS AND METHODS

We determined the prevalence of factor V Leiden and factor II 20210A in 773 consecutive patients with objectively documented symptomatic deep vein thrombosis or symptomatic pulmonary embolism, or with a combination of these disorders.

RESULTS

Isolated symptomatic deep vein thrombosis occurred in 345 patients; isolated symptomatic pulmonary embolism occurred in 236; and both anomalies occurred in 192. Factor V Leiden was present in 21 (9%) of the patients with isolated symptomatic pulmonary embolism, in 30 (16%) with both manifestations, and in 63 (18%) with isolated symptomatic deep vein thrombosis (P = 0.007). Factor V Leiden was more common among patients with deep vein thrombosis (odds ratio [OR] = 2.1; 95% confidence interval [CI]: 1.2 to 3.7; P = 0.006) or both pulmonary embolism and deep vein thrombosis (OR = 1.8; 95% CI: 1.0 to 3.3; P = 0.07) than among patients with isolated pulmonary embolism. Factor V Leiden was less common in massive pulmonary embolism (5% [7 of 127]) than in submassive pulmonary embolism (13% [21 of 155], P = 0.03). We found no significant difference in the prevalence of factor II 20210A among the three groups.

CONCLUSION

Factors V Leiden and II 20210A vary in prevalence among patients with pulmonary embolism and deep vein thrombosis, suggesting that the risk of pulmonary embolization may vary among patients who have different causes of venous thromboses.

[G20210A transition in the prothrombin gene and venous thromboembolic disease]

INTRODUCTION

Genetic predisposition to venous thrombosis can be due to coagulation inhibitor deficiencies (antithrombin, protein C or protein S) or to activated protein C resistance resulting from factor V Leiden mutation (FV Leiden). Poort et al. recently identified a new polymorphism in the 3'-untranslated region of the prothrombin gene, the G20210A transition (FII G20210A), which was found to be associated with an increased risk of venous thrombosis.

EXEGESIS

The prevalence of the A allele is approximately 1 to 4% in the general population, and 5 to 7% in patients with venous thrombosis. Heterozygous carriers have a three to five times increased risk of thrombosis. The diagnosis is based on a polymerase chain reaction technique and restriction enzyme digestion from genomic DNA. Recent studies aim to determine the relative risk of thrombosis and the clinical features which are associated with the mutation (age of first thrombosis, recurrence). The thrombotic risk seems to be higher when FII G20210A transition is associated with the FV Leiden mutation.

CONCLUSION

The presence of heterozygous FII G20210A transition does not modify the management of acute thrombotic events but can lead to an increase in the duration of the anticoagulant treatment. When such a genetic abnormality is identified, thorough information of the patient is needed, including on the prophylactic heparin in high-risk situations and caution on the prescription of oral contraceptives containing estrogens.

The A20210 allele in the prothrombin gene enhances the risk of venous thrombosis in carriers of inherited protein S deficiency

Sixteen families with inherited protein S deficiency and venous thromboembolism (VT) were screened for the presence of factor V (FV) Leiden mutation and for the G20210A allele in the prothrombin gene. While FV Leiden was not detected in any of the families, protein S deficiency and prothrombin mutation were present in five families. To assess the risk of VT in carriers of the combined defects, a total of 92 members of the 16 families, including propositi, were examined. Thirty subjects were normal, 40 showed protein S deficiency, 10 the prothrombin mutation and 12 showed both abnormalities. When index cases were excluded, thrombosis history were present in 40.7% of protein S-deficient patients, 75% of patients with combined abnormality, one out of the 10 (10%) with prothrombin mutation and only one (3.3%) of the normal subjects. Relatives with combined defects showed the highest incidence rate of VT in comparison with normal relatives (rate ratio = 32.4), those with protein S deficiency an intermediate degree (rate ratio = 15.7), and G20210A relatives the lowest (rate ratio = 3.4). Relatives with combined defects had an increased risk of VT in comparison with relatives with protein S deficiency (incidence rate ratio 2.1; 95% confidence interval, 0.7-5.41; P = 0.1). In conclusion, the presence of the prothrombin mutation seems to increase the risk of VT carriers of protein S deficiency, although additional families are required to fully estimate the magnitude of risk.