Factor V Leiden and prothrombin gene G20210A mutation in children with venous thromboembolism

To determine whether factor V Leiden (FVL) and/or prothrombin gene G20210A mutation (PT20210A) are risk factors for venous thromboembolism (VTE) in Argentinean children. One hundred and thirty consecutive children with VTE were prospectively assisted at a single centre. Blood samples were available from 110 of them for detailed haematological analysis. The prevalence of both mutations was compared with a control group. The odds ratio for VTE was significantly increased in patients with FVL (OR 3.64; 95% CI: 1.14-11.6, p < 0.029) whereas odds ratio for VTE was not significantly increased in patients with PT20210A (OR 1.06; 95% CI: 0.24-4.73, p = 0.938). Combined disorders were found in 5 of the 10 children with the aforementioned mutations. In 21 children (19%) without these mutations other inherited and acquired disorders were detected. Our data show that FVL is a risk factor for VTE whereas PT20210A does not seem to be a risk factor in our paediatric population.     

Cerebral and systemic venous thrombosis associated to prothrombin G20210 mutation: case report

Cerebral venous thrombosis is a clinical condition of difficult diagnosis, and poor prognosis when treatment is not started early. There is a long list of causes, and hereby we describe a case associated to prothrombin G20210 mutation. A 53-year-old man, white, was admitted with status epilepticus. After seizures control, he developed intracranial hypertension, with headache and vomiting, and bilateral papilledema. His past medical and familial history were unremarkable. He was a nonsmoker, no drug and alcohol user. CT scan and MRI showed right temporal and parietal infarct with hemorrhagic transformation. Spinal tap with opening pressure of 500 mmH2O showed normal CSF examination. MRI angiography disclosed superior sinus, right transverse and sigmoid sinus complete thrombosis. He was started with heparin and oral warfarin. In spite of anticoagulation, two months later he developed deep right inferior limb thrombosis. All the initial tests were normal, and test for prothrombin G20210 mutation was positive. He needed a much higher than conventional daily dose of warfarin to keep him asymptomatic.     

Factor V gene G1691A mutation,prothrombin gene G20210A mutation,and MTHFR gene C677T mutation are not risk factors for pulmonary thromboembolism in Chinese population

A mutation in coagulant factor V gene, a substitution in the 3' untranslated region of prothrombin gene, and a variant in 5,10-methylenetetrahydrofolate reductase (MTHFR) gene have been reported to be related to venous thromboembolism in Caucasians, but this relationship remains in debate in other populations. In this case-control study, we aimed to determine the prevalence of these three mutations in the Chinese population and investigate whether they are associated with pulmonary thromboembolism. The subjects consisted of 90 patients with pulmonary thromboembolism and 143 age- and sex-matched healthy controls. Traditional risk factors for venous thrombosis and pulmonary thromboembolism were investigated as well. We found that the frequencies of varicose vein, phlebitis, trauma, and surgery were significantly higher in cases than in controls. Of all subjects, none was a carrier of coagulant factor V gene G1691A mutation or prothrombin gene G 20210A mutation, which are common point mutations in Caucasians, while the frequency of MTHFR gene 677T allele exceeded 55% in cases (56.7%), controls (55.2%), and all subjects (55.8%) studied. The homozygous mutation rate of MTHFR gene was over 30% in both cases (33.3%) and controls (32.2%), but no significant difference was found in genotype distribution (chi(2)=0.100, P=0.951). Model fitting using logistic regression did not find that MTHFR gene C677T mutation was associated with pulmonary thromboembolism, consistent with the results of stratification analysis. In conclusion, coagulant factor V gene G1691A mutation and prothrombin G20210A mutation are very rare, while MTHFR C677T mutation is very common, and all of them are not associated with pulmonary thromboembolism in the Chinese population.     

Obstetric complications and pregnancy-related venous thromboembolism: the effect of low-molecular-weight heparin on their prevention in carriers of factor V Leiden or prothrombin G20210A mutation

Whether the administration of low-molecular-weight heparin (LMWH) during pregnancy is effective in preventing obstetric complications and pregnancy-related venous thromboembolism (VTE) in women who are carriers of factor V Leiden (FVL) and/or prothrombin variant G20210A (PTm) is controversial. This observational study investigated the possible efficacy of pharmacological treatment with LMWH ± aspirin (ASA) in pregnancy outcomes in 1,011 pregnancies of 416 women with thrombophilia (FVL and/or PTm). Most patients were chosen on the basis of previous obstetrical complications (36%), or because of familial or personal history of venous/arterial thromboembolism (28% and 18%, respectively); 74 patients (18%) were incidentally identified. The outcome was evaluated according to the type of treatment and of the period of pregnancy when the treatment was started. After adjustment for observation before and after diagnosis of thrombophilia, previous miscarriages and VTE, parity, age and centre, we observed that LMWH had a protective effect on miscarriages (odds ratio [OR] 0.52, 95% confidence interval [CI] 0.29-0.94) and VTE (OR 0.05, 95% CI 0.01-0.21). ASA appeared to have no effect on the prevention of obstetric complications and VTE. A nested analysis performed in 116 women with two or more obstetric complications confirmed that the highest number of live births was recorded in the group under LMWH prophylaxis (OR 0.19, 95% CI 0.05-0.75). These results suggest that LMWH prophylaxis reduces the risk of obstetric complications in carriers of FVL and/or PTm, particularly in those with previous obstetric events. Furthermore, LMWH prophylaxis reduces the risk of pregnancy-related VTE.     

Allele 4G of gene PAI-1 associated with prothrombin mutation G20210A increases the risk for venous thrombosis

Several studies have tried to clarify the role of polymorphism 4G/5G of the PAI-1 gene in venous thromboembolism without reaching any final conclusion. It has been demonstrated that this polymorphism may induce an increased risk for venous thromboembolism (VTE) in patients with thrombophilic defects. We studied the association of prothrombin mutation G20210A with 4G/5G polymorphism in 402 VTE patients and 466 healthy controls. Patients affected by prothrombin mutation G20210A, with or without the concomitant presence of allele 4G, had a 3.7 thrombotic risk (C.I. 95% 2.3-6.0; p<0.0001). Moreover, genotype 4G/4G is a mild risk factor for VTE, irrespectively of whether the prothrombin mutation was present. Logistic regression analysis showed that patients carrying the G20210A prothrombin mutation with allele 4G gave an odds ratio for VTE of 6.1 (C.I. 95% 3.2-11.4; p<0.001). The risk increased up to 13.0 (C.I. 95% 3.0-60.4; p<0.001) when we considered the association of the prothrombin mutation with genotype 4G/4G. The G20210A mutation without allele 4G (5G/5G) was not a risk factor for VTE. In conclusion, we believe that patients affected by VTE with concomitant presence of the G20210A prothrombin mutation could be tested for genotype 4G/4G to better define their thrombotic risk.     

Cerebral vein thrombosis and prothrombin gene (G20210A) mutation

Recently, prothrombin gene mutation G20210A has been associated with elevated thrombosis risk and rarely with cerebral vein thrombosis (CVT). Three patients are described who had this genetic predisposition and who developed CVT in an unusual constellation with other factors. In the first patient, the intake of valproic acid (VPA) may have played an aggravating role in the development of CVT; in the second patient diagnosis of coagulation disorder was made during pregnancy consultation 6 years after CVT; in the third patient the CVT occurred at the age of 78 years. In patients with CVT, coagulation-examinations should include tests for the prothrombin gene (G20210A) mutation.     

The risk of early recurrent venous thromboembolism after oral anticoagulant therapy in patients with the G20210A transition in the prothrombin gene.

A G20210A transition in the prothrombin gene is a common risk factor of venous thrombosis. The risk of recurrent venous thromboembolism in carriers of the 20210A allele is unknown and guidelines for secondary thromboprophylaxis in these patients are not available. In a prospective multicenter trial, 492 patients with a history of objectively documented venous thromboembolism were followed for a mean observation time of 24+/-16 months after discontinuation of oral anticoagulants. Forty-two patients (8.5%) were carriers of the 20210A allele. Three of the 42 patients with the G20210A mutation (7%) and 54 of 450 patients without the mutation (12%) experienced recurrent venous thrombosis. At 24 months, the probability of recurrence was 8% (95% CI 0-16.7) in patients with the mutation and was 12.2% (95% CI 8.8-15.6) in patients without the mutation. In conclusion, the risk of early recurrent venous thromboembolism is not higher in patients with the G20210A mutation than in those without the mutation. Therefore, long-term secondary thromboprophylaxis with oral anticoagulants in heterozygous carriers of the 20210A allele is not justified.     

Increased plasma prothrombin concentration in cirrhotic patients with portal vein thrombosis and prothrombin G20210A mutation

It was the aim of the present study to investigate factor II levels in liver cirrhosis (LC) patients with portal vein thrombosis (PVT) carrying the heterozygous G20210A prothrombin (PT) mutation. Plasma concentrations of factor II, VII, X, V, protein C (PC) total protein S (tPS) antithrombin (AT) and D-dimers (DD) were measured in 13 LC patients with PVT heterozygous for PT G20210A, in 13 LC patients with PVT without PT G20210A and in 13 LC controls matched by age, sex and Child-Pugh score. Crude factor II and factor II/DD ratio were highest in LC patients with PVT heterozygous for PT G20210A (p = 0.03 and p = 0.02 respectively). The factor II/PC ratio, expression of a procoagulant/anticoagulant imbalance was highest in the same group (p = 0.0008). Plasma factor II levels are elevated in LC patients heterozygous for PT G20210A and may favour PVT.     

Prothrombin activity and concentration in healthy subjects with and without the prothrombin G20210A mutation

A synthetic pentasaccharide, containing an intact antithrombin III (ATIII) binding site that is in clinical studies a specific antifactor Xa agent, serves as a substrate for a heparin lyase (heparinase I, EC 4.2.2.7) from Flavobacterium heparinum. Heparinase I, currently being assessed as a heparin reversal agent, also reverses the antifactor Xa activity of this synthetic pentasaccharide by breaking it down to inactive disaccharide and trisaccharide products.