Cardiovascular and thrombophilic risk factors in patients with retinal artery occlusion.

This article evaluates the prevalence of cardiovascular and thrombophilic risk factors in patients with retinal artery occlusion. Forty-one patients with a first episode of a retinal artery occlusion underwent complete ophthalmic examination, routine blood testing and specific laboratory tests for thrombophilia, such as fasting and postmethionine homocysteine, lipoprotein(a), plasminogen activator inhibitor-1, factor VIII, factor V Leiden, factor II G20210A polymorphism, lupus anticoagulant and anticardiolipin antibodies. The control population consisted of 100 healthy individuals comparable as regards age and sex. At univariate analysis, hypertension, smoking, dyslipidaemia (both high cholesterol and triglyceride levels), antiphospholipid antibodies, hyperhomocysteinaemia, elevated factor VIII and lipoprotein(a) levels were significantly associated with retinal artery occlusion; at multivariate analysis, adjusted for age, sex, traditional and thrombophilic risk factors, smoking, hypercholesterolaemia, elevated homocysteine and lipoprotein(a) levels confirmed their independent role as risk factors for retinal artery occlusion. In conclusion, the results of the present pilot study demonstrate that the prevalence of hypercholesterolaemia and smoking and the 'thrombophilic burden' are increased in patients with retinal artery occlusion. Our findings may have implications for the management of these patients, suggesting the need for an intensive and tailored secondary prevention and new therapeutic approaches.     

Activated protein C resistance is a risk factor for central retinal vein occlusion

Central retinal vein occlusion is one of the most common retinal vascular disorders. Few and contrasting data are available on the prevalence of hemostatic risk factors in patients with central retinal vein occlusion. The aim of this study was to investigate the most common hemostasis-related inherited risk factors for venous thrombosis in a group of 53 central retinal vein occlusion patients (median age 59 years, range 18-77 years) and in 53 comparable control subjects (median age 57 years, range 22-84 years). No difference was found in antithrombin III, protein C and protein S plasma levels between patients and controls. At univariate analysis, activated protein C resistance (odds ratio 5.8) and factor V Leiden (odds ratio 4.4) were significantly associated with central retinal vein occlusion whereas G20210A polymorphism of the prothrombin gene was not. After adjustment for sex, age, and the other classic vascular risk factors (hypertension, diabetes, hypercholesterolemia, smoking) activated protein C resistance remained the only independent risk factor for central retinal vein occlusion (odds ratio 11.5). These data indicate that activated protein C resistance may play a role in the pathophysiology of central retinal vein occlusion.     

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.     

Hypercoagulable States in Patients with Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) patients have an increased risk for venous thromboembolism, mainly portal venous thrombosis (PVT). The aim of this study was to assess the role of acquired and hereditary thrombotic risk factors in HCC patients. Thirty-one patients with HCC, 30 patients with cirrhosis but without HCC or PVT, and 48 matched healthy controls were studied. Mean levels of plasma protein C, protein S, antithrombin, and serum lipoprotein (a) were significantly lower in patients with HCC and in the cirrhotic group compared to the healthy controls. Mean serum homocysteine levels were significantly higher in patients with HCC compared to cirrhotics and healthy controls. The prevalence of activated protein C resistance, factor V Leiden mutation, prothrombin gene mutation G20210GA, and C677T methylenetetrahydrofolate reductase polymorphism was not significantly different among the three groups. In conclusion, thrombophilic defects are common in HCC patients and they might contribute to the observed thrombotic complications in this malignancy.     

Role of thrombophilia in vascular access thrombosis among chronic hemodialysis patients in Tunisia

Vascular access thrombosis represents a serious and common problem in hemodialysis patients. Therefore, identification of relevant thrombotic risk factors could lead to an improved antithrombotic therapy. This case control study was performed to evaluate the relationship between some thrombophilias and vascular access thrombosis in hemodialysis patients. Seventy-eight patients undergoing dialysis (between May 2007 and September 2009) were selected as subjects. This sample was divided into two groups; a case group of 28 patients who had sustained one or more thrombotic events that resulted in vascular access failure and a control group of 50 patients, who had never had a thrombotic occlusion of a functioning permanent dialysis access. Antithrombin, protein C and protein S levels were measured. Also, both groups were tested for the factor V Leiden mutation, the prothrombin G20210A mutation, the methylene tetrahydrofolate reductase C677T and A1298C mutations. Among genetic mutations of factor V Leiden, prothrombin G20210A and methylene tetrahydrofolate reductase genes, the C677T methylene tetrahydrofolate reductase mutation was the only significant genetic cause of vascular access thrombosis (P=0.005). Our data demonstrated a significantly increased risk of vascular access thrombosis in carriers of the C677T methylene tetrahydrofolate reductase mutation.     

Prevalence of hereditary thrombophilia in patients with thrombosis in different venous systems

The prevalence of hereditary thrombophilia is well known in patients with lower-extremity thrombosis but only poorly studied in patients with thrombosis at unusual sites. Consequently, it is still unclear whether such patients should generally be screened for hereditary thrombophilia. We retrospectively analyzed 260 patients with thrombosis at unusual sites including thrombosis in portal, cerebral, retinal, and upper-extremity veins with respect to the prevalence of FV Leiden, prothrombin G20210A, protein C, protein S, and antithrombin deficiency. In addition, all thrombotic episodes were analyzed for circumstantial risk factors. Used as controls, healthy volunteers (120) and patients with lower-extremity thrombosis (292) showed overall prevalence of hereditary thrombophilia of 9.1% and 39.0%, respectively. The corresponding numbers were 33.3%, 34.3%, and 39.0% in patients with portal vein, upper-extremity, and lower-extremity thrombosis, respectively. In patients with cerebral vein thrombosis, however, the prevalence was significantly lower (23.5%). Patients with retinal vein occlusion did not show an increased frequency of thrombophilia at all (5.9%). In all five groups FV Leiden was by far the most frequent defect (4.4-27.1%), while prothrombin G20210A occurred rarer (2.5-7.6%). Protein C, protein S, and antithrombin deficiency were much less prevalent (0-3.1%) except for patients with portal vein thrombosis (4.8-7.1%). Compared to healthy individuals, the relative risk of thrombosis was 4.3 (2.2-8.1), 3.8 (1.8-7.7), 2.5 (1.0-6.1), 3.7 (1.5-8.6), and 0.6 (0.2-2.1) for patients with lower-extremity, upper-extremity, cerebral vein, portal vein, and retinal vein thrombosis, respectively. Circumstantial risk factors were more frequent in patients without than with hereditary thrombophilia and were found most often in patients with upper-extremity thrombosis. In each group the most frequent circumstantial risk factor was different. However, oral contraceptives and cancer were found in all five groups. In conclusion, independent upon the presence of circumstantial risk factors, screening for hereditary thrombophilia is warranted in all patients with thrombosis at unusual sites except in those with retinal vein occlusion.     

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.     

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.     

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.     

The prothrombin gene G20210A variant: prevalence in a U.K. anticoagulant clinic population

We have investigated the prevalence of a recently reported genetic variation in the prothrombin gene (G20210A) in patients with an objectively confirmed history of venous thrombosis. 12/219 patients (5.5%) were found to be heterozygous carriers of the 20210 A allele. The incidence of the 20210 A allele in a group of 164 healthy controls was 1.2% (allele frequency 0.61%, 95% CI 0.08–2.19). When patients with a known alternative hereditary risk factor for venous thrombosis (factor V Leiden mutation or deficiency of antithrombin, protein C or protein S) were excluded, the G20210A variant was found to increase the risk for venous thrombosis by approximately 5-fold (odds ratio 5.4, 95% CI 1.16–25.0). This prothrombin gene sequence variation adds further to the list of recognized genetic risk factors for thrombophilia.     

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.     

Homocysteinemia as an independent risk factor in the Chinese population at a high risk of coronary artery disease

In this study, we examined whether homocystinemia acted as an independent and important risk factor in the Chinese population at a high risk of coronary artery disease (CAD). The study population included 237 consecutive patients undergoing coronary angiography and was divided into 2 groups. Group A consisted of 138 patients with CAD and group B of 99 patients with normal coronary angiogram. Prevalence of conventional risk factors of CAD including aging, male gender, family history of CAD, smoking, hypertension, dyslipidemia, diabetes, obesity, and increased high-sensitivity C-reactive protein (hs-CRP) was derived and fasting plasma homocysteine was measured. Results showed that level of plasma fasting homocysteine in group A was significantly higher compared with that in group B and homocystinemia was more prevalent in group A than in group B (p <0.001 for the 2 comparisons). Levels of systolic and diastolic blood pressures, fasting serum glucose, total cholesterol, triglycerides, low-density lipoprotein cholesterol, and hs-CRP were higher, whereas level of high-density lipoprotein cholesterol was lower (all p value <0.05) in group A than in group B. Using a multivariate logistic regression model, we identified smoking, hs-CRP, total cholesterol, plasma homocysteine, systolic blood pressure, and high-density lipoprotein cholesterol as independent risk or protective factors of CAD with odds ratios of 3.83, 3.15, 2.51, 2.14, 1.08, and 0.02, respectively. In conclusion, a high homocysteine level is an independent and important risk factor of CAD and the relative risk of CAD conferred by homocystinemia is similar to that of dyslipidemia in the Chinese population at high risk of CAD.     

Prevalence of factor V Leiden (G1691A) and prothrombin (G20210A) among Kurdish population from Western Iran

BACKGROUND: The mutation in factor V (FV) G1691A, known as factor V Leiden, and prothrombin (FII) gene G20210A are the two most prevalent causes of inherited thrombophilia. The present study reports the prevalence of factor V Leiden and the prothrombin G20210A gene mutations among healthy individuals of Kurdish ethnic background in Western Iran. METHODS: Four hundred thirty-four healthy unrelated individuals, 255 male and 179 female, with a mean age of 28.7+/-15.5 from the Kermanshah Province of Iran were studied for prothrombin G20210A mutation. The factor V Leiden mutation was studied in 404 healthy individuals, of whom 232 were male and 172 were female. The factor V Leiden and prothrombin G20210A were detected by polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP) method using Mnl I and Hind III restriction enzymes, respectively. RESULTS: Among 434 individuals studied for prothrombin G20210A mutation seven carried this mutation as heterozygous (four female subjects and three male), giving a prevalence of 1.6% [95% confidence intervals (CI) 0.5-2.7) and an allele frequency of 0.8%. No homozygous prothrombin 20210AA was found. Factor V G1691A mutation was detected as heterozygous in 11 of 404 healthy individuals (five female and six male) and as homozygous in one male indicating a prevalence of 2.97% (95% CI 1.3-4.6) and allele frequency of 1.6%. CONCLUSIONS: Our results indicated that the factor V Leiden and prothrombin G20210A mutations are not rare among populations of Western Iran and that the relationship between venous thrombophilia and these mutations have to be further studied in Western Iran population, which, in turn, may suggest a causal effect.     

Retinal artery occlusion in a patient with factor V Leiden and prothrombin G20210A mutations.

Retinal artery occlusion is rare in young adults, and may be associated with hereditary thrombophilia. We present a 19-year-old male who was evaluated for central retinal artery occlusion and found to be homozygous for the factor V Leiden mutation and heterozygous for the prothrombin G20210A mutation. Anterior chamber paracenthesis resulted in dramatic improvement, but recurring loss of vision necessitated repeated paracenthesis and the addition of aspirin to standard anticoagulation treatment. The literature concerning hereditary thrombophilia and retinal artery occlusion is reviewed, and the synergistic effect of multiple risk factors is emphasized. Screening for hereditary thrombophilia should be considered for young people presenting with unexplained retinal artery occlusion.     

凝血酶原G20210A基因多态性与脑卒中的关系

目的　探讨凝血酶原 (FⅡ )G2 0 2 10A基因多态性与脑卒中的关系。方法　收集脑卒中患者 30 0例 (脑卒中组 )和性别、年龄相匹配的未患脑卒中的健康人或医院内其他与脑血管无关的患者 30 0例 (对照组 ) ,采用聚合酶链反应 限制性片段多态性 (PCR RFLP)方法进行 2 0 2 10G→A变异的分析。结果　FⅡ 2 0 2 10G→A变异 ,脑卒中组2 0 2 10A纯合子为 2例 ,2 0 2 10GA杂合子为 13例 ,对照组无 2 0 2 10A纯合子 ,2 0 2 10GA杂合子为 6例。脑卒中组FⅡ2 0 2 10G→A突变率为 5 % ,对照组突变率为 2 % ,结果显示两组G2 0 2 10A差异有显著性意义 (P =0 .0 0 3)。OR =3,95 %CI:1.0 6～ 4 .94。脑梗死组 2 0 2 10A纯合子为 2例 ,2 0 2 10GA杂合子 11例 ,脑出血组 2 0 2 10GA杂合子为 2例 ,无2 0 2 10A纯合子。脑梗死组FⅡ基因 2 0 2 10G→A突变率为 6 .5 % ,脑出血组突变率为 2 % ,脑梗死组 2 0 2 10A。基因频率为 3.75 % ,脑出血 2 0 2 10A基因频率为 1% ,两组差异有显著性意义 (P <0 .0 5 )。 2 0 2 10G→A突变脑梗死组与对照组比较差异有显著性意义 (P <0 .0 5 ) ,脑出血组与对照组比较差异无显著性意义 (P >0 .0 5 )。结论　FⅡ 2 0 2 10位G→A的突变与脑梗死的发生有关 ,与脑出血关系不明显。     

The frequency of factor V Leiden and concomitance of factor V Leiden with prothrombin G20210A mutation and methylene tetrahydrofolate reductase C677T gene mutation in healthy population of Denizli, Aegean region of Turkey.

Factor V Leiden causing activated protein C resistance is the most common inherited form of thrombophilia leading to thrombosis. Its frequency shows great ethnic and geographic variations. The aim of this study was to determine the frequency of FV Leiden and coinheritance of FV Leiden with two other frequent hereditary thrombophilia causes, namely, prothrombin G20210A and methylene-tetrahydrofolate reductase (MTHFR) C677T mutation in the Aegean region of Turkey. The study population consisted of 1030 (500 men and 530 women) apparently healthy subjects. Functional resistance to activated protein C (APC) was measured by using the test kit STA staclot APC-R ((Diagnostica Stago, Asnieres, France, Cat. No. 00721). In subjects with APC resistance, molecular analyses of FV Leiden and of prothrombin G20210A and MTHFR C677T mutation were performed by using FV-PTH-MTHFR StripA (Vienna Lab, Labordiagnostika GmbH, Austria) kit, which was based on hybridization of polymerase chain reaction (PCR) amplified DNA products with mutation-specific oligonucleotide probes. Functional APC resistance was present in 93 subjects (9%). FV Leiden mutation was found in 87 of 93 subjects with APC resistance by PCR method. The FV Leiden carrier frequency was found to be 8.4% (87/1030). Seventy-six individuals were heterozygous (7.3%), and 11 were homozygous (1.06%). Among the 87 subjects with FV Leiden mutation, 45 subjects had MTHFR C677T gene mutation (7 homozygous, 38 heterozygous) and 4 subjects had heterozygote prothrombin G20210A gene mutation. A combination of FV Leiden and prothrombin G20210A and MTHFR C677T gene mutation was detected in 3 subjects. The results indicate that FV Leiden prevalence is quite high and coexistence of FV Leiden with other hereditary causes of thrombosis such as prothrombin G20210A mutation and MTHFR enzyme defect is not rare in healthy population of Aegean region of Turkey.     

Determinants of fasting and post-methionine homocysteine levels in families predisposed to hyperhomocysteinemia and premature vascular disease.

Elevated plasma total homocysteine (tHcy) levels, either measured in the fasting state or after oral methionine loading, are associated with an increased risk of atherothrombotic disease. Fasting and post-methionine hyperhomocysteinemia (HHC) overlap to a limited extent; both can occur as familial traits. We investigated determinants of fasting, postmethionine and delta (ie, post-methionine minus fasting levels) tHcy levels in 510 subjects of 192 HHC-prone families including 161 patients with clinical vascular disease and 349 without vascular disease. We focused on tHcy levels in relation to levels of vitamin B12, B6 and folate and the methylenetetrahydrofolate reductase (MTHFR) C677T mutation. Multivariate linear analyses adjusted for the presence of vascular disease showed that fasting tHcy was significantly related to folate and vitamin B12, and the presence of the MTHFR TT genotype and the T allele, and to age, smoking habits, and serum levels of creatinine. Both post-methionine and delta tHcy levels were related to serum folate levels, and the presence of the MTHFR TT genotype and the T allele, and to postmenopausal status, and body mass index. An interaction was found between MTHFR TT genotype and serum folate levels for both fasting and post-methionine tHcy, ie, for a given decrease in serum folate, homocysteine levels increased more in subjects with the TT genotype than in those with the CC genotype. Fasting, post-methionine and delta tHcy were higher in patients with vascular disease than in their healthy siblings, but these levels were less dependent on serum folate levels (P<0.05), whereas the effect of MTHFR genotype was stronger (P=0.01). This study found evidence that post-methionine and delta tHcy levels are not only influenced by factors affecting homocysteine transsulfuration but also by factors that affect remethylation. The explained variances of fasting, post-methionine and delta tHcy were 49%, 62%, and 78%, respectively. We also found evidence, in patients with premature vascular disease but not in their healthy siblings, for a factor that increases tHcy levels but weakens the normal inverse relation between folate and tHcy and amplifies the effect of the MTHFR genotype.     

Prevalence of the G20210A prothrombin gene mutation in Northwestern Greece and association with venous thromboembolism.

AIM: The G20210A mutation of the prothrombin gene is a genetic risk factor for venous thromboembolism (VTE). Variability exists in the mutation prevalence in both normal individuals and VTE patients. The aim of this study was to determine the mutation prevalence in Northwestern Greece and evaluate its association with VTE. METHODS: Presence of the G20210A mutation was investigated using DNA analysis in 176 consecutive patients with a history of venous thrombosis or pulmonary embolism and in 300 healthy controls, all Caucasian residents of Northwestern Greece. RESULTS: The mutation was present 12 patients (6.8%) and 8 controls (2.7%). The odds ratio for presence of the mutation versus the normal genotype in VTE was 2.7 (95% CI: 1.1 to 6.7), which was statistically significant. The prevalence of the G20210A prothrombin gene mutation in Northwestern Greece is 2.7% (95% CI: 0.8% to 4.4%) with an allele frequency of 1.3% (95% CI: 0.4% to 2.3%). CONCLUSION: The G20210A mutation of the prothrombin gene is associated with VTE in the Caucasian residents of this geographic region.     

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.     

Factor V Leiden mutation and PAI-1 gene 4G/5G genotype in thrombotic patients with Behcet's disease.

Behcet's disease is a chronic systemic vasculitis with particular systemic features including thrombotic events. The present study was designed to analyse the role of the factor V Leiden and the prothrombin G20210A mutations and plasminogen activator inhibitor-1 4G/5G polymorphism on the thrombotic risk of patients with Behcet's disease. A total of 50 unrelated patients with Behcet's disease (34 male, 16 female) were the subjects of the study. Twenty-seven of 50 patients with a history of thrombosis comprised group 1, and 23 patients with no thrombosis comprised group 2. In group 1, nine of the 27 patients (33%) were found to have the factor V Leiden mutation (7.1% in healthy population), and the 4G/4G genotype was found in 23% of the patients (26% in control). No patient had the prothrombin G20210A mutation (2.2% in healthy control). In group 2, two patients (9%) had the factor V Leiden and one patient (4%) had the prothrombin G20210A mutations. The 4G/4G polymorphism was found in 30.5% of the patients. The differences in the frequencies of factor V Leiden mutation between group 1 and group 2 (odds ratio, 5.3; 95% confidence interval, 1.0-27.5) and between group 1 and the healthy population were statistically significant ( 0.05). No statistically significant association was found for the prothrombin G20210A mutation and the 4G/5G genotype between the two groups or between each group and the healthy population, indicating that the prothrombin G20210A mutation and the 4G/4G polymorphism do not play a role in the development of thrombosis in Behcet's disease. These data suggested that the factor V Leiden mutation might be a risk factor for the development of thrombosis in Behcet's disease patients.