Multiple thrombophilic factors in a patient with Budd-Chiari syndrome

Myeloproliferative disorders are the main cause of Budd-Chiari syndrome in western countries. Inherited or acquired thrombophilic factors have also been implicated. A novel mutation of the prothrombin gene (G-->A20210) has only been described in a few cases of Budd-Chiari syndrome so far. Venous thrombosis is often the result of multiple concomitant thrombophilic factors. We report the case of a patient with essential thrombocythemia and Budd-Chiari syndrome in which heterozygosity for both factor V Leiden and the mutation G20210A of the prothrombin gene were identified.     

Interaction of estrogen replacement therapy with the thrombophilic 20210 G/A prothrombin gene mutation for atherothrombotic vascular disease: a cross-sectional study of 275 hyperlipidemic women

In a consecutive case series, cross-sectional study of 275 women referred for therapy of hyperlipidemia, (75 [27%] on estrogen replacement therapy [ERT]), our specific aim was to determine whether ERT-mediated thrombophilia and heterozygosity for the thrombophilic 20210 G/A prothrombin gene mutation interacted as risk factors for atherothrombotic cardiovascular disease (ATCVD). Of the 275 women, 100 (36%) had ATCVD; 10 (3.6%) were heterozygous for the 20210 G/A prothrombin gene mutation. In women without the 20210 G/A prothrombin gene mutation, 15 of 71 (21%) on ERT had ATCVD versus 78 of 194 (40%) not on ERT (X(2) = 8.31, P =.004). By stepwise logistic regression, in 261 women with ATCVD risk factor data, positive explanatory variables for ATCVD included the 20210 G/A prothrombin mutation (risk odds ratio, 5.8; 95% confidence intervals [CI], 1.4 to 30.2; P =.021) and a 20210 G/A prothrombin gene mutation*ERT interaction term (risk odds ratio, 2.70; 95% CI, 1.4 to 5.4; P =.004). ATCVD events were more likely in 2 subgroups of women (ERT minus [-] and 20210 G/A prothrombin gene mutation -) or (ERT plus [+] and 20210 G/A prothrombin gene mutation +), P =.004. Other positive explanatory variables for ATCVD events included age (P =.004), triglycerides (P =.012), lipoprotein (a) (P =.03), and homocysteine (P =.032). ERT may be protective against ATCVD when the thrombophilic 20210 G/A prothrombin gene mutation is absent, whereas the 20210 G/A prothrombin gene mutation may increase risk for ATCVD, particularly in the presence of ERT. We suggest that the 20210 G/A prothrombin gene mutation be measured in all women on ERT or before beginning ERT to identify those heterozygous for the thrombophilic prothrombin gene mutation (4%) in whom ERT is contraindicated because of increased risk for ATCVD and thromboembolism, and a second, much larger group of women without the 20210 G/A prothrombin gene mutation (96%) in whom ERT may possibly reduce risk for ATCVD.     

Prevalence of factor Ⅴ Leiden and prothrombin G20210A in patients with gastric cancer

AIM: To analyze the prevalence of the two commonest thrombophilic mutations, factor Ⅴ Leiden and prothrombin G20210A, in patients with gastric cancer.METHODS: One hundred and twenty-one patients with primary gastric carcinoma and 130 healthy subjects,comparable for age and sex, were investigated. Factor Ⅴ Leiden was detected by using polymerase chain reaction and restriction enzyme digestion, and prothrombin G20210A gene mutation by allele-specific PCR.RESULTS: Among the 121 cancer patients, factor Ⅴ Leiden was found in 4 cases (GA genotype: 3.3%) and prothrombin G20210A in 10 cases (GA genotype: 8.3%).Of the 130 control subjects, factor Ⅴ Leiden was detected in 6 cases (GA genotype: 4.6%) and prothrombin G20210A in 8 cases (GA genotype: 6.1%). No double heterozygous carriers of both mutations were found in either group. The prevalence of both factor Ⅴ Leiden and prothrombin G20210A variant was not statistically different between the cancer patients and the healthy subjects.CONCLUSION: Our study suggests that, in gastric cancer, the risk factors of thrombophilic cancer state are on acquired rather than on a genetic basis and that prothrombin G20210A does not seem to be a cofactor in gastric cancer pathogenesis.     

Prevalence of factor V Leiden and prothrombin G20210A in patients with gastric cancer

AIM: To analyze the prevalence of the two commonest thrombophilic mutations, factor V Leiden and prothrom-bin G20210A, in patients with gastric cancer. METHODS: One hundred and twenty-one patients with primary gastric carcinoma and 130 healthy subjects, comparable for age and sex, were investigated. Factor V Leiden was detected by using polymerase chain reaction and restriction enzyme digestion, and prothrombin G20210A gene mutation by allele-specific PCR. RESULTS: Among the 121 cancer patients, factor V Leiden was found in 4 cases (GA genotype: 3.3%) and prothrombin G20210A in 10 cases (GA genotype: 8.3%). Of the 130 control subjects, factor V Leiden was detected in 6 cases (GA genotype: 4.6%) and prothrombin G20210A in 8 cases (GA genotype: 6.1%). No double heterozygous carriers of both mutations were found in either group. The prevalence of both factor V Leiden and prothrombin G20210A variant was not statistically different between the cancer patients and the healthy subjects. CONCLUSION: Our study suggests that, in gastric cancer, the risk factors of thrombophilic cancer state are on acquired rather than on a genetic basis and that prothrombin G20210A does not seem to be a cofactor in gastric cancer pathogenesis.     

Primary thrombophilia in Mexico. II. Factor V G1691A (Leiden), prothrombin G20210A, and methylenetetrahydrofolate reductase C677T polymorphism in thrombophilic Mexican mestizos.

We have shown that in Mexican mestizo patients with clinical features of primary thrombophilia, 39% have activated protein C resistance phenotype, 5% protein C deficiency, and 2% protein S deficiency. In the present study, in a group of 37 thrombophilic Mexicans and 50 normal controls, we assessed the factor V G1691A (Leiden), the prothrombin G20210A, and the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphisms. Four patients were found to be heterozygous for factor V Leiden, 5 heterozygous for the prothrombin 20210, 16 heterozygous, and 6 homozygous for the MTHFR 677. There were four individuals with co-segregation of alleles: two heterozygotes for the factor V Leiden/prothrombin 20210, one heterozygote for prothrombin 20210/MTHFR 677, and one heterozygote for prothrombin 20210/homozygote for MTHFR 677. For factor V Leiden, prothrombin 20210, and MTHFR 677 mutations, the allele frequencies were respectively 1% (+/-0.2%, alpha = 0.05), <1% and 51% (+/-5%, alpha = 0.05), with calculated relative risks for thrombosis of 5.94 (P = 0.08), >7.66 (P < 0.05), and 0.44 (P NS), respectively. In Mexican mestizo thrombophilic patients, the low prevalence of the factor V Leiden mutation (10.8%) and the high prevalence of the prothrombin 20210 mutation (13.5%) contrast with those identified in Caucasian thrombophilic patients (21% and 6%, respectively; P < 0.01). On the other hand, the high prevalence of the MTHFR 677 mutation gene both in normal controls (78%) and thrombophilic patients (61%) does not support a role of this mutation in the thrombogenesis of Mexican mestizo patients.     

Changing profile of Budd Chiari syndrome in India.

There is increasing evidence that Budd Chiari syndrome occurs when acquired predisposing factor(s) affect a susceptible individual with one or more underlying thrombophilic conditions. Geographical variations in disease pattern of Budd Chiari syndrome exist, which may reflect differing predisposing factors. We review a change in disease profile of Budd Chiari syndrome in India over the past three decades. While earlier studies from India reported isolated inferior vena cava (IVC) obstruction as the commonest disease type, this is a minority in more recent reports where a combination of IVC and hepatic vein obstruction is the commonest type. Longer duration of illness has been shown to be associated with IVC obstruction and the recent change in disease profile in India may reflect earlier diagnosis of Budd Chiari syndrome. Poverty, malnutrition, recurrent bacterial infections and filariasis have been previously suggested as predisposing factors for IVC obstruction. Improvement in hygiene and sanitation may partly explain the recent change in disease profile of Budd Chiari syndrome in India.     

Familial thrombophilia and the prothrombin 20210A mutation: association with increased thrombin generation and unusual thrombosis.

The 20210A prothrombin mutation has recently been associated with an increased risk of venous thrombosis, but the mechanism of the increased thrombotic risk in affected persons has not been elucidated. We report on a thrombophilic family in which the proband presented with cerebral vein thrombosis and homozygosity for the 20210A prothrombin mutation as her only identifiable risk factor for venous thrombosis. Extended genotyping of family members revealed seven other affected, but asymptomatic, first-degree relatives (one A/A homozygote and six G/A heterozygotes). Plasma levels of prothrombin, prothrombin fragments 1 + 2 and thrombin-antithrombin complexes were highest in A/A homozygotes, intermediate in G/A heterozygotes and lowest in those with the G/G homozygous normal genotype, while D-dimer levels were elevated only in A/A homozygotes. Our results suggest that the 20210A prothrombin mutation is associated with activation of coagulation and increased thrombin generation, not only in patients with a past history of thrombosis but also in otherwise healthy asymptomatic persons. In a similar fashion to the homozygous factor V Leiden mutation, patients with the homozygous 20210A prothrombin mutation could be at highest risk of thrombosis, as suggested by our patient who presented with unusual thrombosis.     

Case Report: Prothrombin 20210G/A Mutation in Two Patients with Mesenteric Ischemia

Primary cases of splanchnic vein thrombosis are now less common since a systematic screening for hypercoagulability is performed. In 1996, a sequence variation in the 3'-untranslated region of the prothrombin gene (F.II 20210G/A mutation) has been linked to a threefold increased risk for venous thrombosis. The role of this thrombophilic disorder is not documented in patients with thrombosis of the splanchnic veins. This report presents two patients with a mesenteric ischemia associated with a heterozygous state for the F.II 20210G/A mutation. The first patient developed an ischemic colitis and the second one an ischemic necrosis of the terminal ileum related to a thrombosis of the superior mesenteric vein. In both cases, another thrombotic risk factor was associated: either a general prothrombic state (primary antiphospholipid syndrome) or a focal factor (abnormal hemodynamic conditions related to a liver cirrhosis). It has recently been proposed that several conditions need to be combined for deep vein thrombosis to develop. Screening for the combination of multiple underlying prothrombotic conditions thus appears justified in patients with splanchnic thrombosis. The role of the F.II 20210G/A mutation as a predisposing factor for thrombosis of the digestive vessels should be considered and needs further investigation.     

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.     

The prevalence and clinical significance of inherited thrombophilic risk factors in patients with antiphospholipid syndrome

In this study, we evaluated common inherited thrombophilic risk factors in patients with antiphospholipid syndrome (APS), and reviewed relevant literature. Ninety-four APS patients with documented thrombosis, 40 patients with persistent antiphospholipid antibody (aPLA) positivity but without thrombosis, and healthy controls were screened. We found that inherited protein C, protein S, and antithrombin deficiencies were rare in APS patients. The presence of factor V Leiden G506A (FVL) mutation was significantly higher in APS patients with thrombosis compared to healthy controls (11.2% versus 4.9%, P = 0.0043). The prevalence of prothrombin G20210A mutation, however was not significantly increased in APS patients with thrombosis compared to patients without thrombosis (2.7% versus 1.25%, P = 0.67). Our literature review suggested that FVL mutation was associated with both arterial and venous thrombosis but prothrombin G20210A mutation does not seem to contribute much to thrombotic risk in patients with APS. In conclusion, the presence of FVL mutation may define a small but important subgroup of patients who had high risk of both venous and arterial thrombosis. Known thrombophilic risk factors however, may influence the development of thrombotic complications in approximately 10% of APS patients. These findings may indicate that thrombotic complications in APS patients are largely related with aPLA-mediated mechanisms.     

Hereditary Thrombophilic Factors in Stroke Due to Cerebral Infarct

BackgroundThe stroke is the third most common cause of all deaths. In new studies, the importance of hereditary thrombophilic factors on stroke is emphasized. The aim of this study is to determine the role of hereditary thrombophilic factors including factor V Leiden A1691G (FVL), prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T gene mutations in patients with stroke because of cerebral infarct.MethodsTwenty-four patients with stroke and 53 controls with risk factor for stroke were enrolled. Polymerase chain reaction was used to detect these mutations.ResultsHeterozygote FVL mutation in 2 (8.3%) patients and MTHFR mutation in 10 (41.7%) patients were detected. In the control group, there were 2 (3.8%) patients with heterozygote FVL mutation and 15 (28.3%) patients with MTHR mutation. Both FVL and MTHFR gene mutations were detected in 1 patient and 2 controls, respectively. Prothrombin gene mutation was not found in 2 groups. There were not statistically significant differences for all 3 mutations in-between 2 groups (P > 0.05). Odds ratios were 0.431 (0.074–2.504, 95% CI) for FVL mutation and 0.553 (0.221–1.381, 95% CI) for MTHFR mutation, respectively.ConclusionAlthough our study group was small, hereditary thrombophilic factors might not be risk factors for stroke because of cerebral infarct.     

The prothrombin gene variant 20210A in venous and arterial thromboembolism

Several hereditary disorders affecting coagulation factors have been identified as prothrombotic risk factors. Recently, the prothrombin 20210 A/G mutation has been identified as a second important polymorphism involved in venous thrombosis. This article reviews all published information about this new procoagulant mutation. Our group has been involved in a number of studies about the role and importance of polymorphisms in thromboembolic disease, including the analysis of the prothrombin 20210 A/G mutation. Moreover, an extensive Medline literature search was made to complete the review using the key words: prothrombin mutation, 20210, venous or arterial thrombosis. The combination of environmental and genetic risk factors determines the relative risk that any individual has of suffering a thrombotic episode. Some genetic mutations affecting coagulation factors have been described. Recently, Poort et al. described a new mutation in the 3'-untranslated region of the prothrombin gene. The prothrombin 20210 G/A mutation, associated with elevated levels of factor II in plasma, significantly increases the risk of developing venous thrombosis. In fact, this polymorphism is the second most important genetic risk factor for venous thrombosis in Caucasian populations. Moreover, and supporting the multifactorial feature of thromboembolic diseases, this mutation greatly increases the possibility of developing a thrombotic episode when combined with other environmental or genetic risk factors. The role of this procoagulant mutation in arterial vascular disease is, however, unclear.     

Ramifications of four concurrent thrombophilic mutations and one hypofibrinolytic mutation.

A kindred was examined in which the 48-year-old white female proband with three deep venous thrombosis-pulmonary emboli events had four thrombophilic and one hypofibrinolytic mutations, and in which her 14-year-old asymptomatic daughter had four thrombophilic mutations. The proband was heterozygous for the G1691A factor V Leiden, G20210A prothrombin, and platelet glycoprotein IIIa PL A1/A2 mutations, had high factor VIII (221%), and was homozygous for the 4G4G plasminogen activator inhibitor-1 gene mutation, with high plasminogen activator inhibitor activity (23.7 U/mL). Her 14-year-old daughter was homozygous for the G1691A factor V Leiden and platelet glycoprotein IIb-IIIa PL A2/A2 mutations, compound heterozygous for the C677T and A1298C methylenetetrahydrofolate reductase (MTHFR) mutations, and heterozygous for the G20210A prothrombin mutation, a combination with an estimated likelihood of 1.6 x 10(-7). In 247 white healthy controls, there was no V Leiden homozygosity and no V Leiden-prothrombin gene compound heterozygosity. Heterozygosity for the V Leiden and prothrombin gene mutations was 3.2% and 4.1%, respectively. Homozygosity for the platelet glycoprotein IIb-IIIa PL A2A2, PAI-1 gene 4G4G, and C677T MTHFR mutations was 3.2%, 22.7%, and 12%, respectively. The proband will receive anticoagulation therapy for life. Beyond aspirin, avoidance of exogenous estrogens, and enoxaparin prophylaxis during pregnancy, it is not known whether the proband's daughter should have lifelong anticoagulation therapy, or only after her first thrombotic event.     

Association of prothrombin gene mutation with sepsis in a preterm with multiple intracardiac thrombi

We report for the first time, a premature infant with multiple intracardiac thrombi and sepsis, who was heterozygous for the G20210A prothrombin gene variant. Anticoagulant treatment with low molecular weight heparin resulted in the complete disappearance of the thrombi. It may be suggested that prothrombin gene variant associated with sepsis, respiratory distress syndrome, and perinatal asphyxia, as well as other thrombophilic disorders, could be a risk factor for the development of neonatal thrombus.     

Successful liver transplantation in a patient with splanchnic vein thrombosis and pulmonary embolism due to polycythemia vera with Jak2v617f mutation and heparin-induced thrombocytopenia

Heparin-induced thrombocytopenia (HIT) is a rare complication of heparin treatment resulting in a severe acquired thrombophilic condition with an associated mortality of about 10 %. We report the first case of successful urgent liver transplantation (LT) in a patient with end-stage liver disease due to a Budd–Chiari syndrome, portal vein thrombosis and pulmonary embolism due to acquired thrombophilia associated to polycythemia vera carrying JAK2V617F gene mutation and HIT in the acute phase. Lepirudin was used to provide anticoagulation in the LT perioperative period that was performed without haemorrhagic and thrombotic complications despite the donor received heparin during liver explantation.     

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.     

Factor V Leiden G1691A, prothrombin G20210A, and MTHFR C677T mutations in Turkish inflammatory bowel disease patients

BACKGROUND/AIMS: Patients with inflammatory bowel disease (IBD) have an increased risk for thromboembolic complications. We investigated the incidence of factor V Leiden G1691A, methylene tetrahydrofolate reductase (MTHFR) C677T, and prothrombin G20210A mutation in 27 Turkish IBD patients with no history of thromboembolic disease. METHODOLOGY: Twenty-seven patients, 22 with ulcerative colitis (UC) and 5 with Crohn's disease (CD), and 47 healthy were included to the study. The DNAs were obtained from peripheral blood by using pure polymerase chain kit. Then, factor V Leiden G1691A, which active protein C resistance positive, prothrombin G20210A and MTHFR C677T mutations were investigated in DNA by using LightCycler-Factor V Leiden G1691A mutation, Prothrombin G20210A and MTHFR C677T estimate kits. RESULTS: The heterozygote factor V Leiden G1691A mutation was detected in 3 (11.1%) patients with IBD and 2 (4.3%) controls (p > 0.05). The homozygote factor V Leiden G1691A mutation was not estimated among patients and controls. Heterozygote prothrombin G20210A mutation was detected in 2 (7.4%) patients with IBD and in 0 (0%) controls (p > 0.05). There was no homozygote prothrombin G20210A mutation in IBD and controls. Heterozygote MTHFR C677T mutation was 10 of 27 (37%) patients with IBD while 15 of 47 (32%) controls (p > 0.05). Homozygote MTHFR C677T mutation was detected in 4 patients (14.9%) with IBD and 3 (6.3%) controls (p > 0.05). CONCLUSIONS: Our study did not reveal any association between IBD and the most common hereditary thrombophilic factors and these mutations interfere with neither disease manifestations nor the thrombotic complications.     

Prevalence of the G1691A mutation in the factor V gene (factor V Leiden) and the G20210A prothrombin gene mutation in the Thai population

We investigated the prevalence of a genetic variation in the factor V gene (G1691A Leiden mutation) and the prothrombin gene (G20210A) using polymerase chain reaction techniques in samples from 500 normal Thai population and among 50 unselected Thai patients with an objectively confirmed history of deep venous thrombosis. The prevalence of factor V Leiden and the prothrombin G20210A gene mutation in a group of 500 healthy controls was 0.2% in both groups (allele frequency of 0.1%). Of the 50 adult patients studied, none was a carrier of factor V Leiden or the prothrombin G20210A gene mutation. Our findings confirm that the prevalence of factor V Leiden and prothrombin G20210A gene mutation is lower among Asians than Caucasians and that the distribution of factor V Leiden is similar to that of the prothrombin G20210A variant. The low prevalence of these two mutations can, at least in part, account for the lower frequency of deep venous thrombosis reported in the Thai population. Screening for factor V Leiden and prothrombin gene mutation is of limited benefit and may not be cost-effective in Thai patients with the first episode of deep venous thrombosis.     

Risk factors for thrombophilia in young adults presenting with thrombosis

The increased risk for thrombosis is known as hypercoagulability or thrombophilia. Here, we investigated risk factors for thrombophilia which were screened in young adult patients presenting with thrombotic events or with recurrent abortions with unknown etiology. A total of 115 patients aged between 16 and 50 years who were found to harbor thrombophilia were retrospectively evaluated. The laboratory investigations performed for the assessment of thrombophilia included protein C, protein S, antithrombin III deficiencies, activated protein C resistance, factor V Leiden (FVL), prothrombin 20210A (PT 20210) and methylenetetrahydrofolate reductase (MTHFR) gene mutations, factor VIII elevation, lupus anticoagulant and antiphospholipid antibodies (APA). In 66% of the cases a single thrombophilic defect was identified while some of the patients had combined thrombophilic defects. The most common thrombophilic defect was mutation in the MTHFR gene, and was followed by FVL mutation, the presence of APA and PT 20210 gene mutation, respectively. The patients were divided into two different age groups, 16–35 and 36–50 years, and arterial thrombosis was more common in the older age group. Our results indicated that some important thrombophilic defects such as gene mutations may appear in young adult patients presenting with thrombotic events.     

Factor V Leiden mutation in Turkish patients with homozygous cystathionine beta-synthase deficiency

Venous and arterial thromboembolism can occur in patients with homocystinuria. Resistance to activated protein C, which is caused by a single point mutation in the gene for factor V, renders an individual at risk for thrombosis. It has been suggested that coexistence of hereditary homocystinuria and factor V Leiden mutation might jointly play a role in the development of thrombosis. We analysed six patients with homocystinuria due to cystathionine -synthase deficiency for factor V Leiden and prothrombin G20210A mutations. Only one patient was found to have the factor V Leiden mutation in homozygous form and this patient had suffered from severe thrombosis. One patient was found to be heterozygous with no documented thrombosis. None of the patients had prothrombin G20210A mutation. We stress the necessity for screening for known thrombophilic risk factors in patients with cystathonine -synthase deficiency. The coexistence of the factor V Leiden mutation can cause severe thrombotic events in patients with homocystinuria.