Prevalence of the Factor V Leiden Mutation Arg534Gln in Western Region of Saudi Arabia: Functional Alteration and Association Study With Different Populations.

The rare Gln534 (Factor V Leiden; FVL) allele (1:169,519,049 T>C) is associated with an increased risk of venous thrombosis. The purpose of this study was to measure the prevalence of Factor V Leiden mutation in thrombophilia patients with deep vein thrombosis. Also, we investigated the functional and structural characteristics of this mutation p.(Arg534Gln) to be examined the cumulative impact on venous thrombosis risk as well correlated with different populations by Genome Wide Association Studies (GWAS). A total of 108 patients with idiopathic deep vein thrombosis were examined for Factor V Leiden gene mutation. Our preliminary data show that about 10% of patients were detected with the heterozygous and homozygous form of the Factor V Leiden mutation. An association analysis confirmed that the Factor V SNP variant (rs6025) was highly associated (P-value 4.91 x10-^ -39) with an increased risk of venous thrombosis. Also, we found that the recognized SNP was important among HapMap populations. Our results indicated that among the 3 populations (Asian, African, and American) studied, this association was highest in the African population based on the r(2) significant threshold (P-value 5e-190). In addition, this mutation was located at the domain F5/8 type A 2, which can disturb this domain and abolish its function. Because of aspartic acid nearby wild type position as form in the salt bridge due to this discharge will disturb the ionic interaction made by the wild type residue Arg534. This residue was not found to be in contact with other domains of which the function was known. However, contact with other molecules or domains (THPH2: MIM: 188055) were still possible and might be affected by this mutation that may cause thrombophilia due to activated protein C resistance.

Evaluation of Factor V Leiden and prothrombin G20210A mutations in Sudanese women with severe preeclampsia.

BACKGROUND: Preeclampsia (PE) is a common pregnancy complication and one of the main causes of maternal and fetal morbidity and mortality, worldwide. While the pathogenesis of PE is unclear, it has been suggested that hypercoagulability due to Factor V Leiden (FVL) and prothrombin gene mutation (FII G20210A) play a role in its progression. PURPOSE: This study aimed to determine if there is an association between FVL and FII G20210A mutations and severe PE. PATIENTS AND METHODS: This case-control study enrolled 50 women with severe PE and 50 healthy pregnant women as the control, at Khartoum North Teaching Hospital, in Khartoum State, Sudan, from January 2017 to June 2017. The presence of point mutations in FVL and FII G20210A were determined for each of the participants. Deoxyribonucleic acid (DNA) was extracted, and then an allele-specific polymerase chain reaction (PCR) was used to detect the point mutations in FVL and FII G20210A. RESULTS: The results revealed a significant difference between the subjects in the severe PE group and the control group for the means of parity, gestational age/ week and hemoglobin concentration (P < 0.05). No statistically significant body mass index (BMI) differences were found between the groups (P > 0.05). Women with severe PE were found to have a significant difference in FVL (16%; P value = 0.0058; OR: 20.20; 95%CI: 1.132-360.5) and FII G20210A (14%; P value = 0.0125; OR: 17.41; 95%CI: 0.9659-314.0) in comparison to the women in the control group (0%). CONCLUSION: Our findings intensely indicate that there is a statistically proven significant association between FVL, FII G20210A mutations and the development of severe preeclampsia in Sudanese pregnant women.

Placenta-mediated pregnancy complications are not associated with fetal or paternal factor V Leiden mutation.

OBJECTIVE: Maternal thrombophilia is a risk factor for adverse pregnancy outcomes. The aim of this study was to elucidate the controversial role of fetal and paternal thrombophilia in the development of severe placenta-mediated pregnancy complications. STUDY DESIGN: The study group comprised 126 mothers, 72 fetuses and 58 fathers. 111 mothers, 50 fetuses and 91 fathers acted as controls. 106 couples were selected to study the thrombophilias of paternal inheritance, 58 from the study group and 48 from the control group. The prevalence of factor V Leiden mutation, prothrombin G20210 A mutation and homozygous 10-methylenetetrahydrofolate reductase C677 T mutations were compared between the study and control groups to study whether maternal, fetal or paternal thrombophilias increase the risk of severe preeclampsia, intrauterine growth restriction, placental abruption and stillbirth. RESULTS: The total prevalence of fetal thrombophilic mutations was 8.3% in the study group and 14.0% in the control group. Paternal prevalence of thrombophilic mutations was 6.8% and 4.3%, respectively. There were no statistical differences between fetal or paternal thrombophilic mutations between the study and control groups. CONCLUSION: Fetal or paternal factor V Leiden mutation is not associated with severe placenta-mediated pregnancy complications.

Prevalence of Factor V Genetic Variants Associated With Indian APCR Contributing to Thrombotic Risk.

Phenotypic resistance to activated protein C (APC) is a complex mechanism associated with increased thrombosis risk. Activated protein C resistance (APCR) is mainly influenced by FVLeiden mutation, and various other single nucleotide polymorphisms (SNPs) in FV gene are known to be associated with APCR. The aim of present study was to investigate the incidence and assess possible mechanisms of APCR in Indian patients with deep vein thrombosis (DVT). Three hundred and ten Doppler-proven patients with DVT were screened for APCR, and 50 APCR positive patients and 50 controls were typed for FVLeiden, Hong Kong, Cambridge, HR2 haplotype, Glu666Asp, Ala485Lys, and Liverpool using either polymerase chain reaction (PCR)-restriction fragment length polymorphism or allele specific PCR. FVLeiden was commonest cause of APCR (50%) in Indian patients with DVT being statistically significant ( P = .001) compared to controls. FV Liverpool, FV Glu666Asp and FV Ala485Lys were studied for the first time in Indian population. FV Liverpool, FV Glu666Asp, Hong Kong, and Cambridge were found to be absent. High frequency of Ala485Lys in patients shows that it might be a risk factor contributing to APCR in Indian patients with DVT. HR2 haplotype was not associated with APCR; however, presence of homozygous HR2 haplotype in patients only indicates the role it might play in Indian APCR population. In conclusion, contribution of FVLeiden causing APCR in Indian population is not as strong as previously reported in Western countries. The presence of other SNPs observed in the present study requires such studies on larger sample size to understand the molecular basis of defect.

A Study on Hereditary Thrombophilia and Stroke in a Cohort from Sri Lanka.

BACKGROUND: Thrombophilia is an enhanced tendency of arterial or venous blood clot formation. The frequently assessed hereditary thrombophilia mutations associated with stroke are methylenetetrahydrofolate reductase (MTHFR) c.677C>T, Factor V (F5) c.1691G>A (Leiden), and prothrombin (F2) c.20210G>A. The aim of this study was to describe the prevalence of the 3 mutations in ischemic stroke patients in Sri Lanka. METHODS: A database of clinical details and genetic test results of stroke patients referred for thrombophilia screening from June 2006 to April 2014 was maintained prospectively and analyzed retrospectively. RESULTS: A total of 400 ischemic stroke patients (319 arterial, 66 venous, and 15 location unreported) were screened for hereditary thrombophilia. Patients with the MTHFR c.677C>T, F5 c.1691G>A, and F2 c.20210G>A mutations were 17.3%, 3.3%, and .5% of the total cohort, respectively. F5 mutation was present in a statistically significant number of patients with venous thrombosis (P = .005) compared to patients with arterial thrombosis. The MTFHR and F2 mutations showed no such significant association. The mean age of patients with MTHFR, F5, and F2 mutations was 29 (±15), 34 (±11), and 38 (±5.6) years, respectively. CONCLUSION: MTHFR c.677C>T is the predominant mutation and the only mutation that had patients with the homozygous mutant genotype. Venous thrombosis showed a significant association with the F5 c.1691G>A mutation.

Age-specific onset and distribution of the natural anticoagulant deficiency in pediatric thromboembolism.

BACKGROUND: The early diagnosis of inherited thrombophilia in children is challenging because of the rarity and hemostatic maturation. METHODS: We explored protein C (PC), protein S (PS), and antithrombin (AT) deficiencies in 306 thromboembolic patients aged ≤20 y using the screening of plasma activity and genetic analysis. RESULTS: Reduced activities were determined in 122 patients (40%). Low PC patients were most frequently found in the lowest age group (0-2 y, 45%), while low PS or low AT patients were found in the highest age group (16-20 y; PS: 30% and AT: 20%). Genetic study was completed in 62 patients having no other causes of thromboembolism. Mutations were determined in 18 patients (8 PC, 8 PS, and 2 AT genes). Six of eight patients with PC gene mutation were found in age 0-2 y (75%), while six of eight patients with PS gene mutation were in 7-20 y. Two AT gene-mutated patients were older than 4 y. Four PC-deficient and two PS-deficient patients carried compound heterozygous mutations. All but one PC gene-mutated patient suffered from intracranial thromboembolism, while PS/AT gene-mutated patients mostly developed extracranial venous thromboembolism. CONCLUSION: Stroke in low PC infants and deep vein thrombosis in low PS/AT school age children could be targeted for genetic screening of pediatric thrombophilias.

Activated Protein C-Resistance Determination and Vascular Access Thrombosis in Populations with High Prevalence of Factor V Leiden.

BACKGROUND/AIMS: Factor V Leiden heterozygosity occurs in 3-8% of the general European and US populations. Activated protein C resistance (APC-R)--a non-molecular laboratory test--can efficiently demonstrate the presence of this mutation and can be performed on most coagulation analyzers. On the other hand, fistula or graft thrombosis is a common and costly complication in hemodialysis patients. Our aim was to establish the value of APC-R determination in hemodialysis patients by assessing the risk of access thrombosis in patients with increased APC-R. METHODS: A total of 133 patients (81 men, mean age 64.5 ± 14.9 years and 52 women, mean age 63.6 ± 15 years) were selected. Participants were divided into 2 groups: those with access thrombosis (54 patients, 40.6%) and those with no access thrombosis (79 patients, 59.4%), and they were tested for the most common congenital or acquired thrombophilia risk factors. RESULTS: Overall, 12 patients (9%) had an increased APC-R and 10 of them had at least 1 episode of access thrombosis (83.3%). Univariate analysis to estimate crude odds ratio (OR) showed an OR of 8.8 (95% CI 1.8-41.8) times higher risk for access thrombosis in these patients. No significant differences were found after adjusting for age, hypertension, diabetes mellitus, coronary artery disease, cerebrovascular disease, peripheral arterial disease and malignancy. Sex was also a factor influencing thrombosis, presenting a higher OR for women (OR 2.2, 95% CI 1.1-4.4). CONCLUSION: This study revealed a significant association between access thrombosis and increased APC-R in hemodialysis patients. This indicates that the determination of APC-R should be considered--especially, in populations with a high prevalence of Factor V Leiden--as proper anticoagulant therapy in these patients may reduce the risk of access thrombosis.

Venous Thromboembolism after Allogeneic Pediatric Hematopoietic Stem Cell Transplantation: A Single-Center Study.

INTRODUCTION: Venous thromboembolism (VTE) in children who undergo hematopoietic stem cell transplantation (HSCT) has high morbidity. The aim of this study is to assess the incidence of VTE in allogeneic pediatric HSCT recipients and the contribution of pretransplant prothrombotic risk factors to thrombosis. METHODS: We retrospectively evaluated 92 patients between April 2010 and November 2012 undergoing allogeneic HSCT who had completed 100 days post-HSCT. Before HSCT, coagulation profiles; acquired and inherited prothrombotic risk factors including factor V Leiden, prothrombin G20210A, methylenetetrahydrofolate reductase (MTHFR) C677T, and MTHFR A1298C mutations; and serum homocysteine and lipoprotein(a), plasma antithrombin III, protein C, and protein S levels were obtained from all patients. RESULTS: In the screening of thrombophilia, 8 patients (9%) were heterozygous for factor V Leiden, 5 (6%) were homozygous for MTHFR 677TT, 12 (14%) were homozygous for MTHFR 1298CC, and 2 (2%) were heterozygous for prothrombin G20210A mutation. We observed VTE in 5 patients (5.4%); a prothrombotic risk factor was found in 3 out of these 5 patients, while 4 out of 5 patients had central venous catheters. It was determined there was no significant relationship between VTE and inherited prothrombotic risk factors. DISCUSSION AND CONCLUSION: VTE after HSCT seems to be a low-frequency event that may be due to low-dose, low-molecular-weight heparin prophylaxis, and the role of inherited prothrombotic risk factors cannot be entirely excluded without a prospective study.

Risk factors and recurrent thrombotic episodes in patients with cerebral venous thrombosis.

BACKGROUND: The prevalence of thrombophilic abnormalities in patients with cerebral vein thrombosis has been reported to be similar to that in patients with deep vein thrombosis of the lower limb. The role of gender-specific risk factors (pregnancy, oral contraceptives) is well established, whereas that of other acquired risk conditions is debated. MATERIALS AND METHODS: We screened 56 patients with cerebral vein thrombosis and 184 age- and sex-matched apparently healthy controls for prothrombin (factor II, FII) G20210A and factor V Leiden polymorphisms; protein S, protein C, and antithrombin deficiency; anticardiolipin antibodies; hyperhomocysteinaemia and other putative risk factors. RESULTS: The G20210A polymorphism was found in 29.1% of patients and in 5.7% of controls (odds ratio [OR] 7.1; P<0.0001; adjusted OR 12.67, P<0.0001). Frequencies of factor V Leiden and hyperhomocysteinaemia were not significantly different in patients and controls, nor were the other thrombophilic tests and some established cardiovascular risk factors, such as smoking, obesity or overweight and arterial hypertension. Conversely, 53.7% of the women who developed cerebral vein thrombosis did so while assuming oral contraceptives (OR 6.12; P<0.0001), with a further increase of risk in FII G20210A carriers (OR 48.533). Some associated diseases (onco-haematological disorders and infections) also had a significant role. Over a median 7-year follow-up, irrespective of the duration of antithrombotic treatment, 9/56 (16%) patients had further episodes of venous/arterial thrombosis. No significant risk factor for recurrent thrombosis was identified. DISCUSSION: In spite of the limitations of the sample size, our data confirm the role of FII G20210A mutation in this setting and its interactions with acquired risk factors such as oral contraceptives, also highlighting the risk of recurrent thrombosis in cerebral vein thrombosis patients.

Prevalence of thrombophilia according to age at the first manifestation of venous thromboembolism: results from the MAISTHRO registry.

Thrombophilia is a well-established risk factor for a venous thromboembolic event (VTE), and it has been proposed that hereditary thrombophilia may substantially contribute to the development of VTE in young patients. We aimed to analyse the prevalence of thrombophilia with special regard to the age of VTE manifestation. The study cohort consisted of 1490 patients (58% females) with a median age 43 years at the time of their first VTE. At least one thrombophilic disorder was identified in 50·1% of patients. The probability of detecting a hereditary thrombophilia declined significantly with advancing age (from 49·3% in patients aged 20 years and younger to 21·9% in patients over the age of 70 years; P < 0·001). This may be primarily attributed to the decreasing frequencies of the F5 R506Q (factor V Leiden) mutation and deficiencies of protein C or protein S with older age at the time of the initial VTE event. Moreover, thrombophilia was more prevalent in unprovoked compared with risk-associated VTE (57·7% vs. 47·7%; P = 0·001). The decline in the prevalence of hereditary thrombophilia with older ages supports the use of a selected thrombophilia screening strategy dependent on age and the presence or absence of additional VTE risk factors.

Can inherited thrombophilia modulate the clinical phenotype of patients with antiphospholipid syndrome?

OBJECTIVES: The current case-control study was aimed to determine the prevalence and the clinical significance of inherited thrombophilia - factor V Leiden and G20210A prothrombin polymorphisms - in patients with antiphospholipid syndrome (APS). METHODS: 100 patients with APS (77 with primary APS and 23 with systemic lupus erythematosus [SLE]-APS), and 100 patients with first lower extremity deep venous thrombosis (DVT), and 200 healthy individuals as a control groups were analysed. Patients and control group were tested for factor V Leiden and prothrombin G20210A gene polymorphism. RESULTS: Factor V Leiden variant was found in 1% of APS patients, in 3% of healthy individuals (p=0.49), and 16% of patients with first DVT (p<0.0005). Prothrombin gene polymorphism was found in 6% of APS patients and in 2.5% of healthy subjects (p=0.21), and 13% of patients with DVT (p=0.14). In primary APS patients, factor V Leiden was present in 1.3% (1/77) and prothrombin gene polymorphism in 6.5% (5/77). No patient with SLE-APS had factor V Leiden and prothrombin gene variant was present in only one patient (4.3%). Patients with prothrombin polymorphism had higher prevalence of venous thrombosis, with no statistical significance (80% vs. 47.9%, p=0.35). There were no differences in the prevalence of recurrent thrombosis before or after APS diagnosis in patients with or without prothrombin gene polymorphism. CONCLUSIONS: Factor V Leiden and G20210A prothrombin variant seem to play no role in either the development of APS or in the type of involved vessel, with no increased risk of re-thrombosis during follow-up.

Deep vein thrombosis and/or pulmonary embolism concurrent with superficial vein thrombosis of the legs: cross-sectional single center study of prevalence and risk factors.

AIM: The aim of this paper was to assess the prevalence of concurrent deep vein thrombosis (DVT) and/or pulmonary embolism (PE) in the patients with superficial vein thrombosis (SVT) of the legs and to find factors significantly and independently associated with coincident DVT/PE. METHODS: In the setting of a tertiary referral hospital, patients with SVT, attending vascular clinic, underwent physical examination, laboratory testing and leg vein ultrasound (in the case of clinically suspected PE also perfusion/ventilation lung scan or/and helical CT pulmonary angiography). In statistical analysis, we used unpaired t-test, non-parametric Wilcoxon rank sum test, stepwise logistic regression and multivariable logistic regression model. RESULTS: We examined 138 patients (age 61.4 ± 13.9 years, 36.2% men), with ST mostly on varicose veins (89.9%). The prevalence of concurrent DVT/PE was 34.1%. Neither the clinical manifestation nor SVT localization differed significantly between the group with isolated SVT and that with coincident DVT/PE. Of all the assessed patients characteristics (age and sex, BMI, history of SVT, DVT or PE, hypercoagulable states, cardiovascular risk factors) only two factors were significantly and independently associated with the presence of concurrent DVT/PE. Log BMI was significantly higher in the patients with isolated SVT. Factor V Leiden (FVL) was proved as an independent risk factor for concomitant DVT/PE with odds ratio 2,531 (95% CI 1,064-6,016). CONCLUSION: The prevalence of concurrent DVT/PE in patients with SVT, referred to hospital vascular clinic was 34.1%. Lower BMI (log BMI, respectively) and the presence of FVL were significantly and independently associated with concurrent DVT/PE. Our results should be further investigated in a larger prospective study.

Factor V leiden and ischemic stroke risk: the Genetics of Early Onset Stroke (GEOS) study.

BACKGROUND: Factor V Leiden (FVL) has been associated with ischemic stroke in children but not in adults. Although the FVL mutation is associated with increased risk for venous thrombosis, its association with ischemic stroke in young adults remains uncertain. Therefore, we examined the association between FVL and ischemic stroke in participants of the Genetics of Early Onset Stroke (GEOS) study. METHODS: A population-based case control study identified 354 women and 476 men 15 to 49 years of age with first-ever ischemic stroke and 907 controls. Participant-specific data included vascular risk factors, FVL genotype and, for cases, the ischemic stroke subtype by modified Trial of ORG 10172 in Acute Stroke criteria. Logistic regression was used to calculate odds ratios for the entire population and for subgroups stratified by risk factors and ischemic stroke subtype. RESULTS: The frequency of the FVL mutation was similar between ischemic stroke patients (3.6%; 95% confidence interval [CI] 2.5%-5.1%) and nonstroke controls (3.8%; 95% CI 2.7%-5.2%). This frequency did not change significantly when cases were restricted to patients with stroke of undetermined etiology (4.1%; 95% CI 2.6%-6.4%). CONCLUSIONS: Among young adults, we found no evidence for an association between FVL and either all ischemic stroke or the subgroup with stroke of undetermined etiology.

Prevalence of activated protein C resistance (Factor V Leiden) in Lagos, Nigeria.

OBJECTIVES: Hereditary resistance to activated Protein C (Factor V Leiden) is the commonest genetic defect known to confer a predisposition to thrombosis. This study aims to determine the prevalence of activated protein C resistance (APCr) in Lagos, and to determine if any association exists between APCr and ABO, Rhesus blood types, and hemoglobin phenotypes. MATERIALS AND METHODS: A functional APCr test was conducted on healthy adult volunteers to get a Factor-V-related activated protein C ratio (APC-V ratio). APCr due to Factor V mutation was indicated when the APC-V ratio is below a cut-off value that was determined by calibration. Subjects' hemoglobin, red cell ABO, and Rhesus phenotypes were determined by standard methods. RESULTS: Six (2%) of 297 participants with normal baseline coagulation screening tests had functional resistance to activated protein C (APC-V ratio < 2). None of the six subjects with APCr had history of venous thromboembolism. One of the six subjects was a female but the male sex did not demonstrate a risk of inheritance of APCr (P = 0.39). Four (67%) of the six subjects with APCr were non-O blood group. Whereas only two (0.9%) of 226 non-A subjects (blood groups 0 and B) had APCr, 4 (6%) of 71 subjects with A gene (blood groups A and AB) had APCr. The inheritance of A gene appears to constitute a risk to inheritance of APCr (P = 0.03). No association was demonstrable between APCr and hemoglobin phenotypes. CONCLUSION: Only 2% of the studied population had resistance to APC. The inheritance of blood group A may be a predisposition to APCr.

Prevalence of coagulation factor II G20210A and factor V G1691A Leiden polymorphisms in Chechans, a genetically isolated population in Jordan.

BACKGROUND: Coagulation factor II G20210A and coagulation factor V (Leiden) G1691A single nucleotide polymorphisms (SNPs) are major inherited risk factors of venous thromboembolism. In view of the heterogeneity in their world distribution and lack of sufficient information about their distribution among Chechans, we addressed the prevalence of these SNPs in the Chechan population in Jordan, a genetically isolated population. METHODS AND RESULTS: Factor II G20210A and factor V Leiden SNPs were analysed by polymerase chain reaction and restriction fragment length polymorphism (PCR-RFLP) method and Amplification refractory mutation detection system (ARMS) respectively in 120 random unrelated subjects from the Chechan population in Jordan. Among the subjects studied for factor II G20210A mutation there were three individuals carrying this mutation as heterozygous (one female and two male), giving a prevalence of 2.5 % and an allele frequency of 1.25 %. No homozygous factor II allele was found. Factor V Leiden G1691A mutation was detected as heterozygous in 22 of 120 of individuals (17 female and five male) indicating a prevalence of 18.3 % and allele frequency of 9.2 %. No homozygous allele was found. CONCLUSION: Our results indicated that prevalence of factor II G20210A mutation in the Chechan population is similar to prevalence in Jordan and Caucasian populations (1-6 %) while the prevalence of factor V Leiden was higher in the Chechan population compared to Jordan and Caucasian populations (2-15 %).

Thrombophilia among Chinese women with venous thromboembolism during pregnancy.

AIMS: To assess the prevalence of thrombophilia among Chinese women with venous thromboembolism (VTE) developed during pregnancy. METHODS: Based on information from a tertiary teaching unit, all recorded cases of deep vein thrombosis (DVT) and pulmonary embolism (PE) during pregnancy diagnosed between 1997 and 2005, were assessed for prevalence of thrombophilia. Fifty-five healthy women, who had at least one normal pregnancy but without any previous history of VTE, were recruited as controls. RESULTS: A total of 44 subjects completed thrombophilia screening, of whom 5 (11%) were confirmed to have thrombophilia [protein C (PC) deficiency (2), protein S (PS) deficiency (1), combined PC & PS deficiency (1) and antithrombin III deficiency (1)]. Homozygous 5,10-methylenetetrahydrofolate reductase (C677T) gene mutation was found in 6 (14%) subjects but not in the controls. There was no antiphospholipid syndrome, activated PC resistance, factor V Leiden or prothrombin gene mutations. CONCLUSION: In the Chinese population, PS and PC deficiencies are common thrombophilia for VTE during pregnancy and thrombophilia screening should be recommended in all pregnant women who suffer from VTE.