Inherited Thrombophilia Associated With Ischemic Pediatric Stroke in Parent-Child Pairs

BACKGROUND

We aimed to examine inherited thrombophilia frequencies by extending genetic profile to previously rarely or not investigated polymorphisms in children with ischemic pediatric stroke (IPS) and their parents.

METHODS

The study included 33 children: 23 with perinatal arterial ischemic stroke (PAIS), eight with childhood arterial ischemic stroke (CAIS), and two with sinovenous thrombosis and their parents (33 mother-child, 12 father-child, and 12 mother-father-child pairs). Genotyping of FV-Leiden, FV-H1299R, FII-G20210A, β-fibrinogen-455G>A, FXIII-A-Val34Leu, PAI-1(4G/5G), HPA-1, MTHFR-C677T, MTHFR-A1298C, ACE(I/D), and APOE(ε2-4) was performed using CVD Strip assay (ViennaLab, Austria).

RESULTS

At least one and up to seven simultaneously present polymorphisms were observed in all children with IPS, mothers, and fathers. More than five simultaneously present polymorphisms were identified threefold more frequently in children with IPS (10 of 33; 30%) compared with the child control group (17 of 150; 11%), yielding a statistically significant difference between the two groups (odds ratio [OR] = 3.40; 95% confidence interval [CI] = 1.39 to 8.35; P = 0.012). Stronger association was revealed for PAIS (OR = 4.17; 95% CI = 1.55 to 11.29; P = 0.008) and CAIS subgroups (OR = 7.82; 95% CI = 1.79 to 34.20; P = 0.012). Complete match of polymorphisms was not identified in any parent-child pair. A partial match (one to four mutual polymorphisms) was found in 11 of 12 parent-child pairs where until three mutual polymorphisms was present in 11 of 12 (91.7%) father-child compared with 21 of 33 (63.6%) mother-child pairs.

CONCLUSIONS

According to obtained results the simultaneous presence of more than five polymorphisms is associated with a higher risk for IPS occurrence, suggesting the risk enhancement for PAIS in the presence of pregnancy complications or for CAIS in conjunction with maternal comorbidity and positive family history. The presence of up to three mutual polymorphisms more frequently in father-child than mother-child pairs suggests significant paternal contribution of inherited thrombophilia to increased risk of IPS.

Testing for Factor V Leiden (FVL) and Prothrombin G20210A Genetic Variants

Laboratory testing for Factor V Leiden and Prothrombin G20210A genetic variants permits defining the increased relative risk for venous thromboembolism in selected patients. Laboratory DNA testing for these variants may be undertaken by a variety of methods, including fluorescence-based quantitative real-time PCR (qPCR). This is a rapid, simple, robust, and reliable method to identify genotypes of interest. This chapter describes the method that employs PCR amplification of the patient DNA region of interest and genotyping by allele-specific discrimination technology on a quantitative real-time PCR (qPCR) instrument.

Methylenetetrahydrofolate Reductase Gene Polymorphism (C677T) as a Risk Factor for Arterial Thrombosis in Georgian Patients

Methylenetetrahydrofolate reductase (MTHFR) gene polymorphism (C677T)] is a well-recognized genetic risk factor for venous thrombosis; however, its association with arterial thrombosis is still under debate. Herein, we evaluated the prevalence of MTHFR C677T polymorphism in Georgian patients in comparison with healthy individuals and its association with arterial thrombosis. We enrolled 214 participants: 101 with arterial thrombosis (71.3% males; mean age: 66.3 ± 12.1 years) and 113 controls (67.3% males; mean age: 56.6 ± 11.3 years). Genomic DNA was extracted from dry blood spot on Whatman filter paper. Polymerase chain reaction was performed to determine MTHFR C677T polymorphism. Frequency of C677T allele polymorphism in controls was 21.2%, which corresponded to heterozygous and homozygous stage frequencies of 35.4% and 3.5%, respectively. In patient group, an allelic frequency of 33.2% was found, which corresponded to the presence of 48.5% of heterozygous and 8.9% of homozygous individuals. Comparing the frequency of mutated alleles between the 2 groups, a significantly high frequency of mutated alleles was found in patient group (P < .05). In conclusion, high frequency of MTHFR C677T polymorphism found in arterial thrombosis patient group suggests that this polymorphism might increase the risk of arterial thrombosis in Georgian patients.

Thrombophilia genetic testing in Romanian young women with acute thrombotic events: role of Factor V Leiden, Prothrombin G20210A, MTHFR C677T and A1298C polymorphisms / Evaluarea genetică a trombofiliilor la femei tinere din România cu evenimente acute trombotice: rolul Factorului V Leiden, Protrombinei G20210A, polimorfismelor MTHFR C677T și A1298C

Objective: The present case-control study aimed at evaluating the contribution of thrombophilic polymorphisms to acute venous (VTE) as well as arterial thrombotic events (ATE) in a population of young women with few traditional thrombotic factors (CVRF).

Methods: We consecutively enrolled patients under 45 years of age, with less than 3 CVRF, evaluated for VTE or ATE, women and men as a comparator. The control group consisted of healthy young women. A thrombophilia panel and genetic testing for Factor V Leiden (FVL), G20210A Prothrombin and MTHFR polimorphisms were done.

Results: A total of 323 persons were enrolled: 71 women and 121 men with thromboembolic events, and 131 healthy female as controls. Hyperhomocysteinemia was more frequent in ATE (30.4%) than VTE female patients (6.25%), p<0.01. Genetic testing was available in 45 women and 84 men with acute thrombotic events and in all controls. Homozygous FVL was associated with VTE in young women (10.3% vs 0% controls, p<0.01). Prothrombin G20210A polymorphism had the lowest prevalence – 5.4% and only heterozygosity was found. MTHFR C677T heterozygosity showed no significant difference between women patients and controls (62.2 % vs 43.5% respectively, p=0.1). The homozygous status, less frequent (6.6%), was not associated with ATE or VTE. Homozygous MTHFR A1298C was associated with VTE in women (17.2% patients vs 4.5% controls, OR 4.34, p 0.02, CI 1.22-15.3).

Conclusion: In young women with few CVRF, mild hyperhomocysteinemia, homozygosity for FVL and for MTHFR A1298C polymorphisms increase the risk for VTE but not ATE. MTHFR polymorphisms are found with increased frequency in both healthy persons and patients therefore, their significance as an important thrombotic risk modifier remains unclear.

Analysis of Case-Parent Trios Using a Loglinear Model with Adjustment for Transmission Ratio Distortion

Transmission of the two parental alleles to offspring deviating from the Mendelian ratio is termed Transmission Ratio Distortion (TRD), occurs throughout gametic and embryonic development. TRD has been well-studied in animals, but remains largely unknown in humans. The Transmission Disequilibrium Test (TDT) was first proposed to test for association and linkage in case-trios (affected offspring and parents); adjusting for TRD using control-trios was recommended. However, the TDT does not provide risk parameter estimates for different genetic models. A loglinear model was later proposed to provide child and maternal relative risk (RR) estimates of disease, assuming Mendelian transmission. Results from our simulation study showed that case-trios RR estimates using this model are biased in the presence of TRD; power and Type 1 error are compromised. We propose an extended loglinear model adjusting for TRD. Under this extended model, RR estimates, power and Type 1 error are correctly restored. We applied this model to an intrauterine growth restriction dataset, and showed consistent results with a previous approach that adjusted for TRD using control-trios. Our findings suggested the need to adjust for TRD in avoiding spurious results. Documenting TRD in the population is therefore essential for the correct interpretation of genetic association studies.

Association of C677T MTHFR and G20210A FII prothrombin polymorphisms with susceptibility to myocardial infarction

Myocardial infarction (MI) is a common complex pathology, localized in the main leading causes of mortality worldwide. It is the result of the interaction of genetic and environmental factors. The aim of the present study was to investigate the potential association of C677T 5,10-methylenetetrahydrofolate reductase (MTHFR) (rs1801133) and G20210A factor II prothrombin (FII) (rs1799963) polymorphisms with the susceptibility of MI. Following extraction by the standard salting-out procedure, DNA samples of 100 MI patients and 182 apparently healthy controls were genotyped by polymerase chain reaction-restriction fragment length polymorphism using HinfI and HindIII restriction enzymes, respectively. The results show a significant association of the G20210T FII polymorphism with the MI risk. The frequencies of the heterozygote genotype GA, homozygous mutated AA and the G20210A allele was higher among patients compared to controls (GA: 59 vs. 5.5%, P<0.001; AA: 10 vs. 0%, P=0.003; and 20210A: 39.5 vs. 2.7%, P<0.003), suggesting that this polymorphism may be a potential genetic marker for MI. No significant association was observed between the C677T MTHFR and MI occurrence, and there was more heterozygote CT in the patient group compared to the controls. As a multifactorial disease, the development of MI may be the result of numerous factors that influence synergistically its occurrence. Thus, further studies are merited to try to better assess these associations (gene-gene and gene-environment interactions).

Frequency and association of 1691 (G>A) FVL, 20210 (G>A) PT and 677 (C>T) MTHFR with deep vein thrombosis in the population of Bosnia and Herzegovina

The 1691 (G>A) factor V Leiden (FVL) and 20210 (G>A) prothrombin (PT) mutations are the two most common genetic risk factors in venous thromboembolism. The 677 (C>T) methylene tetrahydrofolate reductase (MTHFR) mutation is the most frequently mentioned as an independent genetic risk factor for venous thromboembolism. As there are limited published data on the prevalence of the 1691, 20210 and 677 mutations in our population, the aim of this study was to determine the frequencies and association of these deep vein thrombosis mutations in the Bosnian population.

This study included 111 thromboembolic patients and 207 healthy subjects with absence of known risk factors for venous thromboembolism. Genotyping of the 1691, 20210 and 677 mutations was done by polymerase chain reaction (PCR), followed by restriction digestion with MnlI, HindIII and HinfI enzymes.

Out of the 111 patients, 18.0% were heterozygous and 2.70% were homozygous for the 1691 mutation. Among 207 healthy controls, 3.86%, were heterozygous for the 1691 mutation. This study confirmed the association of the 1691 mutation with deep vein thrombosis in the Bosnian population odds ratio (OR) [95% confidence interval (CI)] = 6.0 (2.62-14.14); p = 0.0001). The 20210 mutation was detected in 2.70% of patients and it was totally absent in the control group. Allele and genotype frequency of 677 did not differ significantly between the cases and controls (χ² = 1.03; p = 0.309).

Genetic risk factors in patients with deep venous thrombosis, a retrospective case control study on Iranian population

Background

Venous thromboembolism (VTE) could be manifested as deep venous thrombosis (DVT) or pulmonary embolism (PE). DVT is usually the more common manifestation and is usually formation of a thrombus in the deep veins of lower extremities. DVT could occur without known underlying cause (idiopathic thrombosis) which could be a consequence of an inherited underlying risk factor or could be a consequence of provoking events, such as trauma, surgery or acute illness (provoked thrombosis). Our aim in this study was to assess the impact of some previously reported genetic risk factors including, methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C, plasminogen activator inhibitor-1(PAI-1) 4G/5G, prothrombin 20210 and FV Leiden on occurrence of DVT in a population of Iranian patients.

Methods

This long-term study was conducted on 182 patients with DVT and also 250 age and sex matched healthy subjects as control group. The diagnosis of DVT was based on patient’s history, clinical findings, D-dimer test, and confirmed by Doppler ultrasonography. After confirmation of DVT, both groups were assessed for the five mentioned mutations. The relationship between mutations and predisposition to DVT was calculated by using logistic regression and expressed as an OR with a 95 % confidence interval (CI).

Results

Our results revealed that FV Leiden (OR 6.7; 95 % CI = 2.2 to 20.3; P = 0.001), MTHFR C677T (OR 6.0; 95 % CI = 2.2 to 16.4; P < 0.001), MTHFR A1298C (OR 8.3; 95 % CI = 4.4 to 15.8; P < 0.001), and PAI-1 4G/5G (OR 3.8; 95 % CI = 2.1 to 7.2; P < 0.001) mutations were all significantly associated with an increased risk of DVT. Prothrombin 20210 was found in none of the patients and controls.

Conclusion

Our findings suggest that genetic risk factors have a contributory role on occurrence of DVT.

Prothrombotic risk mutations and polymorphisms in patients with hemophilia A – a preliminary study / Polimorfismele și mutațiile cu risc protrombotic la pacienții cu hemofilie A - studiu preliminar

Introduction. In search for explanations of the clinical heterogeneity in patients with haemophilia (PwH) with the same mutation or degree of factor VIII deficiency, the coexistence of single or associated prothrombotic risk mutations has been widely evaluated. Objective. The evaluation of the frequency of prothrombotic risk mutations and polymorphisms in PwH in comparison with the general population. Method. The study was performed on 113 consecutive PwH consisting of PCR technology aiming to detect: factor V Leiden - G 1691A (FVL) and prothrombin (PT) - G 20210 A mutations, methylentetrahydrofolat - reductase (MTHFR) and plasminogen activator inhibitor type 1 (PAI-1) polymorphisms. Results. Within the whole study group, 52.21% patients have been identified with associated prothrombotic risk mutations or polymorphisms, 40.70% with one and 7.08% without any such alterations. The global frequency was characterized by the predominance of PAI-1 polymorphism present in 82.29% and MTHFR in 52.21% of patients. Heterozygous variants of PT G20210A, FV G1691A, MTHFR and PAI-1 were found in 7.96%, 9.73%, 39.82% and 53.98% cases, respectively. According to the disease severity, in 89 patients with severe hemophilia, the following frequencies of polymorphisms were found: for MTHFR 52.80%, for FV G1691A 5.61%, for PT G20210A 8.99% and for PAI-1 polymorphism 79.77%. Conclusions. The frequency of FV, PT and PAI-1 genes alterations in our group of hemophilia patients is higher than in the normal population. Nevertheless, considering their uneven distribution in different ethnic groups and geographical regions, more studies on a larger age- and sex-matched patient population are needed.

Prevalence of genetic prothrombotic risk factors: 1691G > A FV, 20210G > A PT and 677C > T MTHFR mutations in the Bosnian population

BACKGROUND

Venous thrombosis (VT) affects 1-2 out of 10(3) individuals each year. Mutations of 1691G > A FV gene, 20210G > A PT gene and 677C > T gene MTHFR are common in Europe and increase the risk of venous thrombosis. To the authors' knowledge, this is the first report on the prevalence of these mutations in the general population of Bosnia and Herzegovina.

AIM

The aim of this study was to simultaneously analyse main VT associated polymorphisms and compare the results with those published for other European populations.

DATA SOURCES

Electronic databases including Medline and Embase were searched from 1995 to December 2013.

SUBJECTS AND METHODS

The subjects of the study consisted of 100 unrelated healthy people from Bosnia and Herzegovina (82 female and 18 male). The mean age of the cohort was 58.8 (± 10.7) years. PCR-RFLP was used for measurement of allele frequencies.

RESULTS

All three SNPs were found to be polymorphic, with allele frequencies of 6.0%, 6.0% and 37.5% for 1691A FV, 20210A PT and 677T MTHFR, respectively.

CONCLUSION

Further studies on larger cohorts with an adequate female-to-male ratio are necessary to confirm a high prevalence of hereditary thrombophilia in the Bosnian population.

Association between the plasminogen activator inhibitor-1 4G/5G polymorphism and risk of venous thromboembolism: a meta-analysis

INTRODUCTION

The plasminogen activator inhibitor-1 (PAI-1) 4G/5G polymorphism was considered to be associated with risk of venous thromboembolism (VTE), while evidence remains inadequate. To provide a more accurate estimation of this relationship, we performed an updated meta-analysis of all eligible studies.

MATERIALS AND METHODS

A systematical search was performed in PubMed, EMBASE, Wanfang, China National Knowledge Infrastructure (CNKI) and Cqvip databases to identify relevant studies published before March 6(th) 2014. The odds ratios (ORs) with 95% confidence intervals (CIs) were pooled using the fixed/random-effects model using Review Manager 5.1 and STATA 12.0.

RESULTS

A total of 34 studies with 3561 cases and 5693 controls were analyzed. Overall, significant association between the PAI-1 4G/5G variant and VTE risk in total population (dominant model: OR=1.32, 95%CI: 1.13-1.54) was observed. And this variant was also related to the deep vein thrombosis risk (dominant model: OR=1.60, 95%CI: 1.24-2.06, P=0.0003). In the subgroup analyses on ethnicity, significant results were obtained in both Asians (dominant model: OR=2.08, 95%CI: 1.29-3.35, P=0.003) and Caucasians (dominant model: OR=1.31, 95%CI: 1.10-1.56, P=0.003). However, no significant association was found in patients with provoked VTE. In terms of subgroup analyses on co-existence of other thrombotic risk factors, the PAI-1 4G/5G polymorphism was significantly associated with VTE risk in patients with factor V Leiden mutation (dominant model: OR=1.72, 95%CI: 1.17-2.53), but not in patients with cancer or surgery.

CONCLUSION

Our findings demonstrate the role of PAI-1 4G/5G polymorphism being a risk candidate locus for VTE susceptibility, especially in patients with other genetic thrombophilic disorders.

Factor V Leiden and FII 20210 testing in thromboembolic disorders

Factor V Leiden and prothrombin (F2) c.20210G>A mutation detection are very important in order to define the increased relative risk for venous thromboembolism in selected patients. Use of DNA-based methods to detect both mutations has become widely available in clinical diagnostic laboratories, including fluorescence-based quantitative real-time PCR (qPCR). The latter is a rapid, simple, robust and reliable method to identify genotypes of interest. There are several chemistries used for qPCR; this article describes their principles and applicability for Factor V Leiden and prothrombin (F2) c.20210G>A mutation detection.

Hypercoagulable state, pathophysiology, classification and epidemiology

Hypercoagulable state is not a uniform disease. It is a complex condition with an abnormal propensity for thrombosis that may or may not lead to thrombosis, depending on complex gene-gene and gene-environment interactions. The prevalence of the hypercoagulable state depends on the ethnicity and clinical history of the population being studied. The consequences of a hypercoagulable state due to thrombosis of veins and arteries are the most important cause of sickness and death in developed countries at present. Primary hypercoagulable state is an inherited condition caused by the reduced level of natural anticoagulants due to a qualitative defect or quantitative deficiency of an antithrombotic protein, or increased concentrations or function of coagulation factors. Most of the inherited abnormalities recognized to date have little or no effect on arterial thrombosis and are associated primarily with venous thromboembolism. Arterial thrombosis usually develops as a complication of atherosclerosis and patients usually have more than one traditional risk factor. Secondary hypercoagulable states generally occur as a result of a large number of transient or permanent acquired conditions that increase the tendency for formation of blood clots. New epidemiological data and clinical trials suggest that many acquired risk factors in the pathophysiology of arterial and venous thrombosis overlap and coexist for both disorders.

Diagnostic algorithm for thrombophilia screening

Thrombophilia screening is aimed at detecting the most frequent and well-defined causes of venous thrombosis, such as activated protein C resistance/factor V Leiden mutation, prothrombin G20210A gene mutation, deficiencies of natural anticoagulants, such as antithrombin, protein C and protein S, the presence of antiphospholipid antibodies, hyperhomocysteinemia and increased factor VIII activity. At this time, thrombophilia screening is not recommended for those possible congenital or acquired risk factors, whose association with increased risk of thrombosis has not been proven sufficiently. Laboratory investigations should include a step-wise approach to the diagnosis of thrombotic disorders with respect to the assays and methods of analysis that are used. The assays recommended for the first diagnostic step of screening should establish, whether the subject has one of the common causes of thrombophilia. If one or more abnormal results are obtained, the second diagnostic step includes the assays recommended for confirmation and/or characterization of the defect. When performing the investigation of thrombophilia, it is important to consider all pre-analytical and other variables that may affect the results of thrombophilia testing, including time of testing, age, gender, liver function, hormonal status, pregnancy or the acute phase response to inflammatory diseases. This is necessary, in order to avoid, any misinterpretation of the results. This review summarizes the current knowledge concerning thrombophilia investigations, with special focus on the diagnostic algorithm regarding patient selection, the assays and methods of analysis used and all the variables that should be considered when employing tests for the diagnosis of thrombophilia.