Heterozygous Factor Research Articles

Factor V Leiden Mutation and Thrombotic Occlusion of Microsurgical Anastomosis After Free TRAM Flap

The transverse rectus abdominis muscle flap is widely used in free microvascular tissue transfer for breast reconstruction following mastectomy. Flap survival may be compromised by failure at the microsurgical anastomosis due to both venous and arterial thrombosis. It is unclear, whether hereditary thrombophilia represents a risk factor for early thrombotic occlusion following free flap procedures. We present a case of a patient with previously diagnosed activated protein C resistance caused by heterozygous factor V (position 1691 G-->A) Leiden mutation in whom a free transverse rectus abdominis muscle flap was performed. The postoperative course was complicated by repeated thrombosis of both the venous and arterial part of the anastomosis. Immediate thrombectomy and repeated arteriography allowed for partial flap salvage. More data are needed to analyze the impact of hereditary thrombophilia on microvascular anastomosis failure.

Deep Venous Thrombosis Caused by Congenital Malformation of the Inferior Vena Cava and Heterozygous Factor V Leiden Presenting as Venous Claudication

A case of an 18-year-old man with deep venous thrombosis of the lower limbs caused by hypoplasia of the inferior vena cava in combination with heterozygous factor V Leiden is presented. Both anomalies were found when the patient complained of venous claudication in both thighs. Inferior vena cava malformation is a rare condition and may predispose to the development of deep venous thrombosis. This patient was at an even higher risk for deep venous thrombosis as the inferior vena cava malformation was combined with a hypercoagulable state.

Präeklampsie-Screening im 1. und 2. Trimenon

Pre-eclampsia is a pregnancy-associated disease of the second part of the pregnancy, occurring mainly after 20th weeks gestation. The prevalence of hypertension in pregnancy is between 5 to 11% and affects mainly women under 20 years of age. An inadequate invasion of trophoblasts with consequential placental ischemia as a result of insufficiently dilated uterine spiral arteries is thought to be an initial cause in the pathogenesis of pre-eclampsia. The clinical symptoms of pre-eclampsia, such as loss of intravascular volume and edema, are caused by generalized endothelial dysfunction. These symptoms are potentiated by hypertension and reduced colloid osmotic pressure in the plama. The organs being affected by pre-eclampsia are those of the vascular-, hepatic-, renal-, cerebral- and coagulatory systems. The prognosis is much more severe when pre-eclampsia develops very early in the pregnancy. The symptoms include elevated blood pressure (over 140 mmHg systolic, 90 mmHg diastolic) combined with proteinuria. Frequent symptoms are hyperreflexia and edema. The etiology of pre-eclampsia has not been clearly defined. Risk factors/triggers for the development of pre-eclampsia can include chronic hypertension, advanced maternal age at first pregnancy (over 35 y), nephropathy, thrombophilia (heterozygous factor V Leiden mutation, antiphospholipid syndrome, heterozygous prothrombin mutation and homozygous MTHFR), multiple gestation and prior pregnancy with preeclampsia. The incidence of preeclampsia is higher in nulliparous than multiparous women. In many countries pre-eclampsia is still most frequent cause of maternal perinatal mortality. HELLP-Syndrome (haemolysis-elevated liver enzyme- low platelets) is a severe progressive course of this disease. Eclampsia, characterized by generalized tonic-clonic convulsion, is the most dangerous complication of pre-eclampsia, and may develop before or after delivery. This form of pre-eclampsia is associated with higher maternal and fetal mortality. Constant maternal hypertension potentially alter vascular integrity of the placenta with further consequences in fetal blood supply leading to growth restriction or zero growth and subsequently resulting in low birth weight or fetal death. The sooner the disease is detected and confirmed, the better the maternal and fetal prognoses are. This is the reason why it is major importance, together with the employment of preventive measures, to identify patients with risk factors with pre-eclampsia though an adequate screening method, thereby detecting the disease earlier and ensuring better pregnancy outcomes for both mother and child.

Thrombosis risk modification in transgenic mice containing the human fibrinogen thrombin-binding gamma' chain sequence.

Thrombin binding activity in murine fibrin (Antithrombin I) is restricted to its E domains inasmuch as murine gamma' chains (mu-gamma') do not bind thrombin. This feature prompted us to produce a 'gain-of-function' transgenic mouse in which the wild-type (WT) C-terminal mu-gamma' chain fibrinogen sequence had been replaced with the C-terminal thrombin-binding human gamma' sequence. This procedure resulted in a murine fibrinogen species containing chimeric hu-gamma' chains (hu-gamma' fibrinogen). As anticipated, thrombin bound to WT fibrin at a single class of sites, whereas thrombin binding to heterodimeric hu-gamma'-containing fibrin was increased, reflecting its content of hu-gamma' chains. In an electrolytically-induced femoral vein thrombosis injury model, we found no differences in the volume of thrombus generation between WT and heterozygous hu-gamma' mice. However, heterozygous factor (F) V Leiden (FVL(+/-)) mice developed greater thrombus volumes than did WT controls (P < 0.01). In doubly heterozygous FVL(+/-), hu-gamma' mice, thrombus formation was reduced to WT levels (P < 0.05). Murine hu-gamma' fibrinogen down-regulates venous thrombosis in the presence of another known thrombosis risk factor, FV Leiden. This finding indicates that hu-gamma' chain-containing fibrinogen is a thrombosis risk modifier.

Cerebral Venous Thrombosis After Epidural Blood Patch: Coincidence or Causal Relation? A Case Report and Review of the Literature

We report on a female patient who developed post-dural puncture headache (PDPH) after epidural analgesia for delivery. Treatment with epidural blood patch led to complete headache remission and the patient was discharged. Two days later the patient was readmitted with hemihypaesthesia and mild hemiparesis of the right side. Magnetic resonance imaging showed a small left parietal cortical haemorrhage probably following cerebral venous thrombosis (CVT). Coagulation screening detected heterozygous Factor V mutation. Headache is a common symptom of PDPH and CVT. Review of the literature revealed five patients in puerperal state, who developed CVT in close temporal relationship after blood patch treatment for PDPH. Change of headache character with loss of postural influence was reported frequently before diagnosis of CVT was confirmed. These findings may indicate a causal relationship.

An unusual clinical presentation of factor XIII deficiency and issues relating to the monitoring of factor XIII replacement therapy

Congenital factor XIII deficiency is a very rare bleeding disorder. Patients with severe FXIII deficiency usually exhibit severe bleeding diatheses. Factor XIII is also involved in maintaining pregnancy, and women with factor XIII deficiency have a high risk of spontaneous abortions. We report here the case of a patient with a mild bleeding history before her pregnancy but who had three spontaneous haemorrhagic miscarriages. The patient was homozygous for G 501 R mutation of the factor XIII A subunit gene. We also detected a coinherited heterozygous factor V Leiden mutation, probably leading to a milder bleeding tendency. The patient had successful factor XIII replacement therapy throughout her fourth pregnancy. The efficacy of the factor XIII infusions was monitored using thromboelastometry and routine factor XIII measurements. This case report shows that factor XIII deficiency should be ruled out in patients with recurrent fetal loss but with a normal miscarriage workup, even in the absence of a history of severe bleeding since childhood. We also showed that thromboelastometry could be a valuable tool for the monitoring of factor XIII replacement therapy.

Factor V Leiden mutation is associated with improved 30-day survival in patients with acute respiratory distress syndrome

Activation of coagulation and inflammation are parts of the innate host response to infection that may contribute to organ dysfunction and death when control of these systems is compromised. Thus, functional single nucleotide polymorphisms within candidate genes of the inflammation and coagulation cascade are possible factors which may influence severity and/or mortality in acute respiratory distress syndrome. The aim of this study was to investigate whether the factor V Leiden mutation (Arg506Gln) is associated with altered severity and/or mortality in acute respiratory distress syndrome. Retrospective cohort, genetic association study. Tertiary care intensive care unit. Adults (white Germans) with acute respiratory distress syndrome (n = 106). Genotyping for the factor V Leiden mutation. Using Kaplan-Meier estimates to compare outcome, 30-day survival was significantly associated with the factor V Leiden mutation (p = .049). Thirty-day survival rates were 100% for Arg/Gln (n = 7) genotypes but only 58% for Arg/Arg (n = 99) genotypes, respectively. We show for the first time that a heterozygous factor V Leiden genotype is associated with improved 30-day survival in patients with acute respiratory distress syndrome.

Thrombosis in children with cardiac pathology: analysis of acquired and inherited risk factors

The present study was conducted to analyze the features and risk factors of childhood thrombotic events in patients with cardiac defect followed-up at our hospital. The clinical and laboratory findings of 59 patients diagnosed with cardiac defects and thromboses between 1997 and 2006 were retrospectively analyzed. Thirty-one children (52.5%) had venous system thromboses, 21 (35.6%) had arterial system thromboses, and seven (11.9%) had venous and arterial system thromboses. Presence of congenital heart disease and cardiomyopathy (CMP) were significant risk factors for developing intracardiac thrombosis. In addition, presence of congenital heart disease was the significant statistical risk factor for developing left atrium and right ventricle thromboses. Presence of congenital heart disease was a significant risk factor for developing a central nervous system thrombosis. Presence of pulmonary stenosis and aortic coarctation were significant risk factors for developing a peripheral arterial system thrombosis. Acquired risk factors including major surgery, angiography, central venous catheter, systemic infection, and hypoxia were identified in 49 of the 59 patients. Many patients had more than one of these acquired risk factors. Analysis of the relationship between thrombosis and type of major surgery demonstrated a statistically significant relationship between an intracardiac thrombosis and total correction of tetralogy of Fallot and a peripheral venous system thrombosis and a Blalock Taussig shunt. Twenty-three of the 52 patients (44.2%) had at least one thrombophilic mutation. Overall, a heterozygous factor V Leiden mutation was found in nine patients (17.3%), a methylenetetrahydrofolate reductase 677C-T mutation in 15 patients (28.8%), and a PT 20210G-A mutation in three patients (5.8%). Our data suggest that cardiac defects are common risk factors for developing a childhood thrombosis. The type of disorder determines the site of thrombosis. Acquired risk factors may contribute to the development of a thrombosis. The results of this study also indicate that to ensure early diagnosis, routine screening for thrombosis should be performed in patients with a cardiac defect and that screening for factor V Leiden and PT 20210G-A mutations and other genetic risk factors should be included when assessing all patients with cardiac defects who present with a thrombosis, whether or not a predisposing factor has been identified.

A rare case of arterial thrombosis in a 37-year-old male with Factor V Leiden mutation

The classic triad of symptoms seen in chronic mesenteric ischaemia is post-prandial pain, sitophobia (fear of food) and progressive weight loss. Patients with mesenteric ischaemia secondary to a prothrombotic state such as that rendered by the Factor V Leiden mutation, are substantially younger than the typical elderly patient in whom embolic disease triggered by atrial fibrillation is the main underlying cause. This is one such case report documenting arterial thrombosis in a 37-year-old male with a subsequently identified heterozygous Factor V Leiden mutation. Factor V Leiden mutation is a contributing risk factor in cases of small bowel infarction.

A Clinical Perspective of Venous Thromboembolism

A large number of individuals develop venous thromboembolism (VTE) every year.1 Each patient’s episode of DVT or PE is, naturally, unique. To highlight a variety of aspects about VTE a compilation case is presented that is composed of clinical data and images from several real patients. ### History of Present Illness A 36-year-old woman presents to the Emergency Department with severe shortness of breath and moderately intense anterior chest pain, worse on deep inspiration, which had started suddenly that morning. She also reports a 6-wk history of mild shortness of breath, for which she had been seen 4 wk earlier by her primary care physician who diagnosed her with “asthma.” Bronchodilators and steroids were prescribed but led to no significant improvement in her symptoms. She also gives a history of mild left calf pain that had started about 2 months earlier without preceding trauma, immobilization, or surgery. Her primary care physician had seen her and prescribed Ibuprofen for a “pulled muscle.” However, in the 1 week before her present presentation her leg symptoms worsened, and she had increased diffuse leg pain and swelling and slightly bluish discoloration of the whole leg. Her past medical history is only significant for an appendectomy at age 16. She has never been pregnant. She is on no medications, except for an estrogen and progestin-containing oral contraceptive, started 10 months earlier. She does not smoke. There is no family history of venous thromboembolism, although the patient reports that her paternal grandmother had a “swollen leg for many years” until she died in her 70’s, but no further details are known of the patient. ### Physical Examination The patient’s weight is 86 kg and her height 165 cm, calculating to a body mass index (weight divided by [height in meters]2) of 31.6 kg/m2, ie, she has grade 1 obesity. Her …

Thrombophilia differences in cerebral venous sinus and lower extremity deep venous thrombosis

To characterize differences in the prevalence of thrombophilic variables in a large cohort of patients with cerebral venous sinus thrombosis (CVST) and lower extremity deep vein thrombosis (DVT). An inception cohort of individuals was identified with first lifetime incident CVST between 1995 and 2005 for whom comprehensive thrombophilia testing was available. To test the hypothesis that thrombophilia prevalence differs with respect to thrombus location, test results were compared to a randomly selected group of patients with lower extremity DVT with comprehensive thrombophilia testing. During this time period, 163 patients with CVST were identified who underwent comprehensive thrombophilia testing. Thrombophilia results were abnormal in 29% including anticardiolipin antibodies (17%), heterozygous factor V Leiden (10%), and heterozygous prothrombin G20210A mutation (n = 14/122; 11%). The prothrombin mutation was more than twice as common in patients with CVST (p = 0.04). Activated protein C resistance, factor V Leiden, and protein C deficiency were more common in patients with DVT (p < 0.05 for each comparison). The anticardiolipin antibodies in patients with CVST were primarily low titer IgM isotype. The prevalence of selected thrombophilia factors differs comparing patients with cerebral venous sinus thrombosis and deep vein thrombosis. These differences may offer insights into mechanisms governing the geographic distribution of venous thrombosis.

Evidence-based indications for thrombophilia screening

Thrombophilic defects have been shown to be associated with an increased risk of venous thrombosis, fetal loss, and gestational complications. The knowledge about the clinical relevance of thrombophilic defects is increasing, and evidence-based indications for thrombophilia screening are therefore discussed in this review. Selective thrombophilia screening based on previous personal and/or family history of venous thromboembolism is more cost-effective than universal screening in all patient groups evaluated. In the majority of patients with acute venous thrombosis, the results of thrombophilia screening do not influence the duration of oral anticoagulation. The only patient population who clearly profits from thrombophilia screening in this situation are patients with a newly diagnosed antiphospholipid syndrome, because prolonged anticoagulation can avoid the high incidence of recurrence in this patient population. Because of the increased risk of venous thrombosis during pregnancy and the puerperium, thrombophilia screening is indicated in selected patients with a previous history of venous thrombosis or a positive family history. Significant associations with early and late pregnancy loss are observed for carriers of the heterozygous factor V Leiden mutation, the heterozygous prothrombin-mutation G20210A and anticardiolipin antibodies, while protein S deficiency is significantly associated with late pregnancy loss. Antithrombotic drugs like UFH, LMWH or low-dose aspirin may have a potential therapeutic benefit in patients with recurrent pregnancy loss and thrombophilia, but placebo-controlled, multicenter trials are urgently needed to clarify this issue. Although a supra-additive effect for the risk of venous thrombosis is observed between oral contraceptives and some thrombophilias, the absolute incidence of venous thromboembolism is low in premenopausal women and mass screening strategies are therefore unlikely to be effective. While antiphospholipid antibodies are known to be associated with arterial thrombosis, screening for heritable thrombophilias is not useful in arterial thrombosis, although subgroup analysis indicates that they may play a role particularly in young patients and children.

Akuter hämorrhagischer Jejunuminfarkt als Erstmanifestation einer APC-Resistenz bei Faktor-V-Leiden-Mutation - ein Fallbericht

We report on a 43-year-old patient presenting to the emergency department with acute abdominal pain the source of which turned out to be acute hemorrhagic jejunal infarction due to portal and mesenteric vein occlusion with no apparent cause. In spite of a lacking history of hereditary thrombophilic risk factors, further diagnostic procedures revealed heterozygous factor V Leiden mutation. Diagnosis, therapy and clinical course are described. An overview on acute mesenteric venous occlusion with special reference to genetically determined thrombophilic disorders is given.

Factor V Leiden mutation and type 1 diabetes mellitus

Diabetes mellitus is considered to cause a tendency for arterial thrombosis. Recent studies addressed the association between venous and arterial disease. Resistance to activated protein C is one of the most common causes of venous thrombosis and linked to a single point mutation in the factor V gene, designated as factor V Leiden mutation. There is little information regarding the status of factor V Leiden mutation in type 1 diabetes. The aim of this study is to evaluate association among activated protein C sensitivity ratio, factor V Leiden mutation, and type 1 diabetes taking into account metabolic control, lipids and diabetic complications. The study population consisted of 47 healthy subjects (27.9 +/- 1.2 years) and 48 type 1 diabetic patients (27.9 +/- 1.1 years). Activated protein C sensitivity ratio was measured by activated partial thromboplastin time based assay. The presence of factor V Leiden mutation was determined by amplifying the fragments encompassing gene mutation by PCR. Mean normalized activated protein C sensitivity ratio values and prevalence of heterozygous factor V Leiden mutation were not significantly different between groups (1.08 +/- 0.03 and 6.3% in healthy subjects; 1.01 +/- 0.03 and 6.4% in type 1 diabetic patients, respectively). The activated protein C sensitivity ratio and factor V Leiden mutation were not found to be linked with metabolic control parameters, lipids and diabetic complications in type 1 diabetic patients. There was no association among factor V Leiden mutation, activated protein C sensitivity ratio and type 1 diabetes, metabolic control parameters as well as complications of diabetes. Although the propensity to thrombosis is increased in individuals with type 1 diabetes, activated protein C sensitivity ratio and factor V Leiden mutation do not appear to be significant determinants.

Cardiovascular Disease, Chronic Kidney Disease, and Type 2 Diabetes Mellitus

<h3>Background</h3> Cardiac involvement is an uncommonly seen but might be a fatal clinical manifestation of Behcet’s syndrome (BS), if not recognized early and treated aggressively. <h3>Objectives</h3> Our aim was to retrospectively evaluate the characteristics of cardiac involvement in Behcet’s syndrome and investigate possible risk factors. <h3>Methods</h3> 800 patients with BS diagnosis according to International Study Group for Behcet’s Disease (ISG) criterias in our center were screened. 14 patients with cardiac involvement were included in this study. <h3>Results</h3> All the patients were male with positive smoking history. The age at the onset cardiac involvement was 32.5 ± 7.8 years. In 3 patients, diagnosis of BS was made simultaneously with cardiac involvement. Types of cardiac involvement were as following; intracardiac thrombosis (ICT) in 8, right coronary artery aneurysm in 2, and myocardial infarction in 4 patients. The majority of ICT was seen in right ventricle followed by right atrium (75% vs 25%). Deep vein thrombosis (DVT) was the most common accompanying other vascular involvement (57%).Thrombophilic factors were studied in 8 patients, whom only 2 cases were found positive for heterozygous factor V Leiden mutation. Cyclophosphamide was the most common used immunosuppressive agent and anticoagulation was used in 9 patients (Table 1). <h3>Conclusion</h3> Most common type of cardiac involvement is pericarditis, whereas intracardiac thrombosis has its unique characteristics (1). Male gender and smoking seems to be major significant risk factors. <h3>References</h3> [1]Wang H, Guo X, Tian Z, Liu Y, Wang Q, Li M, Zeng X, Fang Q (2016) Intracardiac thrombus in patients with Behcet’s disease: clinical correlates, imaging features, and outcome: a retrospective, single-center experience. Clinical Rheumatology 35(10):2501–2507 <h3>Disclosure of Interests</h3> None declared

Arterial thrombosis associated with factor V Leiden and methylenetetrahydrofolate reductase C677T mutation in childhood membranous glomerulonephritis

Acquired abnormalities of coagulation and fibrinolysis in nephrotic syndrome have been implicated in the pathogenesis of deep-vein and arterial thrombosis. A mutation in the factor V and methylenetetrahydrofolate reductase (MTHFR) gene, the commonest inherited risk factor for venous thrombosis, may contribute to the risk of both arterial and deep-vein thrombosis in patients with nephrotic syndrome. Here, we report on an arterial thrombosis in a young girl with idiopathic membranous glomerulonephritis associated with heterozygous factor V Leiden and homozygous MTHFR C677T mutation. We postulate that screening for factors such as factor V Leiden and MTHFR C677T mutation may be beneficial to patients associated with thromboembolism and idiopathic nephrotic syndrome.

Venous Thromboembolic Events in Women Using the NuvaRing®.

Venous thromboembolic events (VTEs) are serious adverse effects seen in some women using oral contraceptives. Although the novel vaginal ring, (NuvaRing®) has been reported to be effective and well tolerated, the risks of VTEs are unknown. We report 3 women who developed potentially life-threatening VTEs (2 with pulmonary emboli and 1 inferior vena cava thrombus) while on the NuvaRing®. VTEs occurred 22 days, 3 months and 3 months after NuvaRing® insertion. None had a personal or family history of VTEs. Extensive thrombophilia evaluation showed 1 with heterozygous factor V Leiden and 2 with a transient lupus anticoagulant. 2 had a personal history of multiple miscarriages and all 3 had an elevated body mass index &gt; 26. Searching Pubmed, Ovid and Medline, there have been 10 other reported cases of VTEs, in women using the vaginal ring (see table below). Risk factors reported by other authors include anticardiolipin antibodies, protein S deficiency, heterozygous prothrombin 20210, heterozygous factor V Leiden and prolonged air travel. With limited follow up, the true incidence of VTEs in women using the NuvaRing® is difficult to determine. However, in 2005 the Swedish Medical Products Agency reported a relative incidence of 5.3 cases per 10,000 women years for VTE complications. In summary, we report 3 women who had life-threatening VTEs associated with the use of the NuvaRing®. Longer follow-up of safety studies and post-marketing adverse event reporting are needed to determine VTE risks and incidence while using the NuvaRing®. Studies reporting VTEs in women using the NuvaRing® Source Number of patients VTE risk factors Family history Site Bjarnadottir et al, 2002 1/121 Unknown Unknown LE DVT Tuppurainen el al, 2004 1/40 Unknown Unknown LE DVT Oddsson et al, 2005 1/512 Unknown Unknown LE DVT Miller et al, 2005 1/429 Anticardiolipin antibodies, protein S deficiency Grandmother with DVT LE DVT Ahrendt et al, 2006 1/499 Double heterozygous factor V Leiden/prothrombin 20210, prolonged air travel Unknown LE DVT Roumen et al, 2006 1/854 Unknown Unknown Cerebral sinus thrombosis Samuelsson et al, 2007 1 Heterozygous prothrombin 20210 None Axillary vein DVT Swedish Medical Products Agency, 2005 4/? Unknown Unknown DVTs Shum et al, 2007 3 Obesity (3), Personal history of miscarriages (2), heterozygous factor V Leiden (1) 1 sister with miscarriage Bilateral pulmonary emboli (2), Iliac vein-IVC thrombus (1)

Phenylephrine-Induced Microvascular Occlusion Syndrome in a Patient With a Heterozygous Factor V Leiden Mutation

Cutaneous microvascular occlusion syndromes (MOS) present with noninflammatory retiform purpura with variable outcomes that are dependent on the severity, duration, and specific underlying cause. Transient cases are often associated with few sequelae, while severe forms such as symmetrical peripheral gangrene may be associated with amputation and death. A middle-aged man developed MOS after exposure to phenylephrine hydrochloride and experienced complete resolution when treatment with the vasopressor was discontinued. Further evaluation detected a previously subclinical heterozygous factor V Leiden mutation. We propose that phenylephrine-mediated vasoconstriction superimposed on an underlying thrombotic predisposition precipitated the transient MOS. The role of vasopressors in the development of cutaneous MOS is well documented in the critical care literature; however, it is underrepresented in the dermatologic literature, and, to our knowledge, there are no reports of phenylephrine use inducing MOS. We hope to raise awareness of the potential role of vasopressor medications in causing MOS.

Shigatoxin-2 does not result in thrombotic microangiopathy in heterozygous factor H-deficient mice

Shigatoxin-2 does not result in thrombotic microangiopathy in heterozygous factor H-deficient mice

Thrombophilic mutations among Southern Iranian patients with sickle cell disease: high prevalence of factor V Leiden

A hypercoagulable state in sickle cell disease (SCD) and beta thalassemia has been established and thrombosis is an important aspect of the clinical spectrum of sickle cell disease. In a case-control study, the prevalence of factor V Leiden and prothrombin G20210A mutations were investigated among SCD patients from Southern Iran. Patients comprised 60 individuals with SCD; of them 35 were with sickle cell anemia (SS) including 21 males and 14 females aged 17.2+/-8.3 years, 15 were sickle cell trait (AS) consisted of nine males and six females aged 30+/-15.4 years and 10 were sickle/beta thalassemia (S/Thal) (three males and seven females) aged 24.6+/-10.4 years. The control group were 126 apparently healthy individuals (50 males and 76 females) aged 20.1+/-9.8 years. Genotyping was done by polymerase chain reaction restriction fragment-length polymorphism (PCR-RFLP) using Mnl I and Hind III for factor V Leiden and prothrombin G20210A, respectively. Heterozygous factor V Leiden mutation was found in five of 35 (14.3%) SS patients, two of 15 (13.3%) AS individuals, one (a sickle/beta-zero thalassemia patient with IVSII.1 G-->A mutation) of 10 S/Thal patients (10%), and two of 126 (1.6%) control subjects (P<0.05). However, only one AS individual (6.7%) was found to be a carrier for prothrombin G20210A compared to five of 126 (4%) healthy individuals. Adjusted logistic regression analysis for the effects of age and sex was performed and a significant association was found between factor V Leiden mutation and sickle cell anemia with odds ratios (OR) of 6.5 (95% confidence intervals [CI] 1.19-35.33, P=0.03) in SS patients. However, increased prevalence of the factor V Leiden in AS individuals and S/Thal patients was not statistically significant compared to controls (OR 3.84, 95% CI 0.49-29.9, P=0.19 and OR 3.77, 95% CI 0.31-45.9, P=0.29, respectively). Our findings indicate a significant correlation between factor V Leiden and sickle cell anemia among Iranian patients. Association between venous thrombophilia and factor V Leiden mutation in Iranians with sickle cell anemia should be further studied.