Factor II G20210A and Factor V G1691A Gene Mutations and Peripheral Arterial Occlusive Disease

Systematic review and meta-analysis of the genetics of peripheral arterial disease

Background

Peripheral artery disease (PAD) impacts more than 200 million people worldwide. The understanding of the genetics of the disease and its clinical implications continue to evolve. This systematic review provides a comprehensive summary of all DNA variants that have been studied in association with the diagnosis and progression of PAD, with a meta-analysis of the ones replicated in the literature.

Methods

A systematic review of all studies examining DNA variants associated with the diagnosis and progression of PAD was performed. Candidate gene and genome-wide association studies (GWAS) were included. A meta-analysis of 13 variants derived from earlier smaller candidate gene studies of the diagnosis of PAD was performed. The literature on the progression of PAD was limited, and a meta-analysis was not feasible because of the heterogeneity in the criteria used to characterize it.

Results

A total of 231 DNA variants in 112 papers were studied for the association with the diagnosis of PAD. There were significant variations in the definition of PAD and the selection of controls in the various studies. GWAS have established 19 variants associated with the diagnosis of PAD that were replicated in several large patient cohorts. Only variants in intercellular adhesion molecule-1 (rs5498), IL-6 (rs1800795), and hepatic lipase (rs2070895) showed significant association with the diagnosis of PAD. However, these variants were not noted in the published GWAS.

Conclusions

Genetic research in the diagnosis of PAD has significant heterogeneity, but recent GWAS have demonstrated variants consistently associated with the disease. More research focusing on the progression of PAD is needed to identify patients at risk of adverse events and develop strategies that would improve their outcomes.

Peripheral Arterial Disease Genetics: Progress to Date and Challenges Ahead

PURPOSE OF REVIEW

In this paper, we review the progress made thus far in research related to the genetics of peripheral arterial disease (PAD) by detailing efforts to date in heritability, linkage analyses, and candidate gene studies. We further summarize more contemporary genome-wide association studies (GWAS) and epigenetic studies of PAD. Finally, we review current challenges and future avenues of advanced research in PAD genetics including whole genome sequencing studies.

RECENT FINDINGS

Studies have estimated the heritability of PAD to be moderate, though the contribution to this heritability that is independent of traditional cardiovascular risk factors remains unclear. Recent efforts have identified SNPs associated with PAD in GWAS analyses, but these have yet to be replicated in independent studies. Much remains to be discovered in the field of PAD genetics. An improved understanding of the genetic foundation for PAD will allow for earlier diagnosis of disease and a more complete pathophysiological understanding of the mechanisms of the disease leading to novel therapeutic interventions. Future avenues for success will likely arise from very large-scale GWAS, whole genome sequencing, and epigenetic studies involving very well-characterized cohorts.

Association analysis of genetic polymorphisms of factor V, factor VII and fibrinogen β chain genes with human abdominal aortic aneurysm

Increased activity of the coagulation system is associated with the increased risk of many arterial thrombotic diseases and atherosclerosis. The purpose of this study was to evaluate the influence of selected polymorphisms in genes coding for coagulation factor V (1691 G/A, the so-called Leiden mutation), factor VII (−323 0/10 bp insertion/deletion) and fibrinogen β chain (−455 G/A) on the risk of abdominal aortic aneurysm, a particular form of atherothrombosis. We conducted a case-control study of 153 Polish patients hospitalized due to abdominal aortic aneurysm (AAA) and compared the results to those obtained from matched healthy control subjects. The polymorphisms were ascertained through genotyping by polymerase chain reaction and restriction digestion of amplified fragments. The study revealed that individuals carrying heterozygous genotype GA for the fibrinogen β chain −455 G/A mutation had at least a 2-fold greater likelihood of AAA development compared to control subjects (OR=3.01; 95% CI 1.83–4.96). The cases possessing homozygous mutant genotype (AA) had no significant risk of developing AAA compared to the control subjects (OR=1.12; 95% CI 0.33–2.44; p=0.83). Concerning factor V 1691 G/A and factor VII −323 0/10 bp mutations, we did not find any statistically significant correlation between them and AAA occurrence. In conclusion, we suggest that the −455G/A polymorphism of the fibrinogen β chain gene is a potential genetic marker to identify the risk of AAA.

Peripheral artery disease and genetics: is there a cause-and-effect relationship?

Peripheral artery disease (PAD) is a major health problem worldwide, affecting millions of patients. Although cardiovascular risk factors, such as diabetes, tobacco use, hypertension, and hypercholesterolemia have been associated with the development of PAD, the possible existence of an inherited genetic predisposition to PAD has been investigated in numerous familial aggregation studies. A link between genetics and PAD may open new avenues for the prevention of this morbid and mortal disorder. This is an overview of the potential association between genetics and PAD.

The fibrinogen gamma 10034C>T polymorphism is not associated with Peripheral Arterial Disease

Conversion of fibrinogen to fibrin plays an essential role in hemostasis and results in stabilization of the fibrin clot. Fibrinogen consists of three pairs of non-identical polypeptide chains, encoded by different genes (fibrinogen alpha [FGA], fibrinogen beta [FGB] and fibrinogen gamma [FGG]). A functional single nucleotide polymorphism (SNP) in the 3' untranslated region of the FGG gene (FGG 10034C>T, rs2066865) has been associated with deep venous thrombosis and myocardial infarction. Aim of the present study was to analyze the role of this polymorphism in peripheral arterial disease (PAD). The study was designed as case-control study including 891 patients with documented PAD and 777 control subjects. FGG genotypes were determined by exonuclease (TaqMan) assays. FGG genotype frequencies were not significantly different between PAD patients (CC: 57.3%, CT: 36.7%, TT: 5.8%) and control subjects (CC: 60.9%, CT: 33.5%, TT 5.6%; p=0.35). In a multivariate logistic regression analysis including age, sex, smoking, diabetes, arterial hypertension and hypercholesterolemia, the FGG 10034 T variant was not significantly associated with the presence of PAD (Odds ratio 1.07, 95% confidence interval 0.84 - 1.37; p = 0.60). The FGG 10034C>T polymorphism was furthermore not associated with age at onset of PAD. We conclude that the thrombophilic FGG 10034 T gene variant does not contribute to the genetic susceptibility to PAD.

A field synopsis and meta-analysis of genetic association studies in peripheral arterial disease: The CUMAGAS-PAD database

In an electronic search of the literature, the authors systematically retrieved all published studies that investigated genetic susceptibility to peripheral arterial disease (PAD). They created a comprehensive database of all eligible studies, collecting detailed genetic and bioinformatics data on each polymorphism. Data from eligible studies were synthesized using meta-analysis techniques. Gene variants were classified into distinct pathophysiologic pathways, and their potential involvement in PAD pathogenesis was determined. Forty-one publications that examined 44 gene polymorphisms were included. For 37 polymorphisms, the variant form had a functional effect. Twenty-three polymorphisms in 22 potential PAD candidate genes (F2, FGB, MTHFR, ITGB3, ACE, AGT, IL6, CCL2, ICAM1, SELE, MMP9, PPARG, MMP1, ADD1, P2RY12, LIPC, PLA2G7, SCARB1, MMP3, MTTP, LPA, CHRNA3) showed a significant association in individual studies. Eighty-eight percent of the studies had statistical power of less than 50%, and in 15 studies the genotype distribution in the control group did not conform to Hardy-Weinberg equilibrium. Data on 12 polymorphisms (F5 1691 G/A, MTHFR 677C/T, F2 20210 G/A, ITGB3 1565 T/C, ACE I/D, AGT 704C/T, AGT -6G/A, AGT 733C/T, IL6 -174 G/C, MMP9 -1562C/T, ICAM1 1462A/G, CHRNA3 831C/T) were synthesized, and a positive association was found for 3 (IL6 -174 G/C, ICAM1 1462A/G, CHRNA3 831C/T).

[Thrombophilias and peripheral arterial occlusive disease]

Peripheral arterial occlusive disease is a frequent disease due to the classical vascular risk factors such as smoking, diabetes mellitus, dyslipidemia, and hypertension. Despite these risk factors, many thrombophilias (physiological inhibitors defects, Factor V Leiden and 20210A prothrombin gene variant, antiphospholipid antibodies, mild hyperhomocysteinemia 15-30micromol/l) can be evoked in some clinical forms of peripheral arterial occlusive disease. This paper provides a synthesis of the published data about this topic. Screening for these thrombophilias is justified in patients with venous thromboembolic disease, or signs of antiphospholipid syndrome and possibly in different situations such as premature atheroma of lower limbs, chronic ischaemia, evolutive disease despite adapted treatment and revascularisation failures without evident technical explanation. Except for the antiphospholipid syndrome, there is currently no consensus for systematic screening of thrombophilia and treatment in patients with peripheral arterial occlusive disease.

Genetic susceptibility to peripheral arterial disease: a dark corner in vascular biology

Peripheral arterial disease (PAD) is characterized by reduced blood flow to the limbs, usually as a consequence of atherosclerosis, and affects approximately 12 million Americans. It is a common cause of cardiovascular morbidity and an independent predictor of cardiovascular mortality. Similar to other atherosclerotic diseases, such as coronary artery disease, PAD is the result of the complex interplay between injurious environmental stimuli and genetic predisposing factors of the host. Genetic susceptibility to PAD is likely contributed by sequence variants in multiple genes, each with modest effects. Although many of these variants probably alter susceptibility both to PAD and to coronary artery disease, it is likely that there exists a set of variants specifically to alter susceptibility to PAD. Despite the prevalence of PAD and its high societal burden, relatively little is known about such genetic variants. This review summarizes our limited present knowledge and gives an overview of recent, more powerful approaches to elucidating the genetic basis of PAD. We discuss the advantages and limitations of genetic studies and highlight the need for collaborative networks of PAD investigators for shedding light on this dark corner of vascular biology.

Inherited Thrombophilia in Arterial Disease: A Selective Review

Thrombophilia may be defined as an acquired or congenital abnormality of hemostasis predisposing to thrombosis. Because arterial thrombosis is usually linked with classical risk factors such as smoking, hypertension, dyslipidemia, or diabetes, a thrombophilia workup is usually not considered in case of arterial thrombosis. The most accepted inherited hemostatic abnormalities associated with venous thromboembolism are factor V Leiden (FVL) and factor II (FII) G20210A mutations, as well as deficiencies in antithrombin (AT), protein C (PC), and protein S (PS). This review focuses on the link between these abnormalities and arterial thrombosis. Overall, the association between these genetic disorders and the three main arterial complications (myocardial infarction [MI], ischemic stroke [IS], and peripheral arterial disease [PAD]) is modest. Routine screening for these disorders is therefore not warranted in most cases of arterial complications. However, when such an arterial event occurs in a young person, inherited abnormalities of hemostasis seem to play a role, particularly when associated with smoking or oral contraceptive use. These abnormalities also seem to play a role in the risk of premature occlusion after revascularization procedures. Therefore thrombophilia tests may be informative in a very restricted population with arterial events. Anticoagulants rather than antiplatelet therapy may be preferable for these patients, although this remains to be proven.

Role of thrombophilic gene polymorphisms in branch retinal vein occlusion

OBJECTIVE

Branch retinal vein occlusion (BRVO) is a common cause of severe visual loss. Numerous risk factors, including arterial hypertension, diabetes mellitus, and arteriosclerosis, have been identified. Gene polymorphisms affecting hemostasis may also play a role in the pathogenesis of BRVO. The present study was therefore done to determine the prevalence of genetic polymorphisms in factors implicated in hypercoagulability among patients with BRVO.

DESIGN

Retrospective case-control study.

PARTICIPANTS

The study cohort consisted of 294 patients with BRVO and 294 control subjects, matched for age and gender.

METHODS

Determination of genotypes was done by allele-specific digestion of polymerase chain reaction products, or by 5' exonuclease assay (TaqMan).

MAIN OUTCOME PARAMETERS

Genotypes of factor V R506Q (factor V Leiden), prothrombin 20210G>A, fibrinogen beta -455G> A, factor XII (FXII) 46C>T, and ITGA2 807C>T (platelet glycoprotein Ia [GPIa] 807C>T) and ITGB3 L59P (platelet GPIIIa PlA1/PlA2) polymorphisms.

RESULTS

Genotype distributions of the investigated gene polymorphisms did not differ significantly between patients and control subjects. In contrast, significantly increased prevalences of arterial hypertension and hypercholesterolemia were found among patients with BRVO. In a logistic regression analysis, the presence of arterial hypertension was associated with an odds ratio (OR) of 2.32 (95% confidence interval [CI], 1.62-3.32), whereas hypercholesterolemia yielded an OR of 2.54 (95% CI, 1.74-3.70) for BRVO.

CONCLUSION

Our data indicate that the prevalences of the investigated gene polymorphisms do not differ significantly in patients with BRVO and control subjects. This suggests that these polymorphisms are not major risk factors for BRVO.

Factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations are not associated with chronic limb ischemia: the Linz Peripheral Arterial Disease (LIPAD) study

OBJECTIVE

Factor V G1691A (Leiden), prothrombin G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T mutations are considered risk factors for venous thromboembolism. It remains to be characterized whether the presence of these relatively common mutations poses a risk for peripheral arterial disease (PAD). Therefore, we intended to test, by conducting a case-control study, the hypothesis that PAD was associated with an increased prevalence of factor V G1691A, prothrombin G20210A, and MTHFR C677T mutations.

METHODS

The study comprised 433 patients admitted for inpatient diagnostics and treatment of PAD in patients with chronic limb ischemia. Patients with acute ischemia or malignancy were excluded. A total of 433 control subjects matched to the patients with PAD in a 1:1 design by sex, age (+/-2 years), and diabetes mellitus status were recruited. Factor V G1691A, prothrombin G20210A, and MTHFR C677T genotypes were assessed by polymerase chain reaction.

RESULTS

For the factor V G1691A polymorphism, the genotype frequencies in PAD patients were 92.8% GG (normal homozygotes = wild type) and 7.2% GA (mutant heterozygotes), and in control subjects they were 94.0% GG and 6.0% GA (chi 2 test; P = .493). The distribution of the prothrombin G20210A genotypes was 96.3% GG (normal homozygotes = wild type) and 3.7% GA (mutant heterozygotes) in PAD patients and was 97.2% GG and 2.8% GA in control subjects (chi 2 test; P = .442). Genotype frequencies for the MTHFR C677T polymorphism were 47.8% CC (normal homozygotes = wild type), 43.4% CT (mutant heterozygotes), and 8.8% TT (mutant homozygotes) in PAD patients, compared with 47.1% CC, 44.1% CT, and 8.8% TT in control subjects (chi 2 test; P = .977). Accordingly, as determined by logistic regression analysis, no significant odds ratios for heterozygous or homozygous genotypes of the three polymorphisms could be observed.

CONCLUSIONS

PAD was not associated with an increased prevalence of factor V G1691A, prothrombin G20210A, and MTHFR C677T mutations in the population studied. Thus, there is no indication that of one of these mutations may be a risk factor for chronic limb ischemia. However, the role of these mutations in acute limb ischemia remains to be clarified.

Thrombophilic risk factors for symptomatic peripheral arterial disease

OBJECTIVE

Peripheral arterial disease (PAD) is a common manifestation of systemic atherosclerosis. Over the last years, several novel mediators relevant to the process of atherogenesis have been identified, but few and conflicting data are available on the possible association with PAD symptoms. The aim of this study was to determine an extended thrombophilic risk profile of patients with symptomatic PAD.

METHODS

Two hundred eighty patients with symptomatic PAD admitted to the Department of Vascular Surgery of the University of Florence were compared with 280 control subjects without PAD, matched for age and gender. The following metabolic and genetic risk factors were evaluated: lipoprotein(a), homocysteine, antiphospholipid antibodies, plasminogen activator inhibitor-1, factor V Leiden mutation, prothrombin variant, and 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism.

RESULTS

Multivariate logistic regression analysis, adjusted for traditional cardiovascular risk factors, showed a significant association between PAD symptoms and prothrombin variant, altered levels of homocysteine, lipoprotein(a), plasminogen activator inhibitor-1, and antiphospholipid antibodies. Moreover, the presence of high levels of lipoprotein(a) and another metabolic risk factor raised the likelihood of PAD symptoms (dyslipidemia and elevated lipoprotein[a]: odds ratio [OR], 29; 95% confidence interval [CI], 6.2 to 136.2; P <.0001; hyperhomocysteinemia and elevated lipoprotein[a]: OR, 37.7; 95% CI, 3.7 to 381.5; P <.0001). A significant correlation between the number of altered thrombophilic parameters and the Fontaine stage was observed ( R = 0.16; P = .006).

CONCLUSION

There is an independent association between altered levels of important thrombophilic risk factors and PAD symptoms. The clinical significance of this association needs to be tested in prospective population-based trials.

The factor II G20210A gene polymorphism, but not factor V Arg506Gln, is associated with peripheral arterial disease: results of a case-control study

BACKGROUND

The FIIG20210A polymorphism has been associated with arterial wall thickness and atherothrombotic diseases in selected subgroups. The FVArg506Gln polymorphism does not seem to be associated with arterial diseases. Few data are available on these polymorphisms and the risk of peripheral arterial disease (PAD).

OBJECTIVES

To study the association between the FIIG20210A and FVArg506Gln polymorphisms and PAD and its clinical severity. To examine the potential interactions with traditional vascular risk factors.

PATIENTS AND METHODS

We studied 184 consecutive male patients under 70 years of age with symptomatic PAD and 330 age-matched male controls free of symptomatic PAD and with no cardiovascular history. We evaluated the FIIG20210A and FVArg506Gln polymorphisms in all subjects.

RESULTS

Mean age was 57.1 +/- 7.2 years (cases) and 56.7 +/- 7.6 years (controls). The FII20210A allele was more frequent in PAD patients with odds ratios (OR) of 3.77 (1.39-10.2) in univariate analysis and 4.30 (1.3-14.7) after adjustment for diabetes, smoking, hypertension and hypercholesterolemia. In smokers or past smokers the magnitude of the association was markedly increased but there was no evidence of an interaction between tobacco exposure and FIIG20210A. In case subjects, the FII20210A allele was also associated with critical ischemia [OR = 4.1 (1.1-15.7), P = 0.039 in multivariate analysis]. FVArg506Gln was not associated with PAD [OR = 0.65 (0.27-1.54) and 0.77 (0.28-2.1) in univariate and multivariate analyses, respectively].

CONCLUSIONS

The FIIG20210A gene polymorphism may be a risk factor for PAD and its severity. In contrast, the FVArg506Gln polymorphism is not associated with PAD.

Association between factor V Leiden, prothrombin G20210A, and methylenetetrahydrofolate reductase C677T mutations and events of the arterial circulatory system: a meta-analysis of published studies

BACKGROUND

The association between the inherited gene mutations of factor V, prothrombin, and homocysteine metabolism and venous thromboembolic events is accepted widely; however, their influence on the arterial circulatory system remains controversial.

METHODS

We performed a MEDLINE search to identify published case-control and cohort studies correlating the factor V Leiden, prothrombin (PT) G20210A, and methylenetetrahydrofolate reductase (MTHFR) C677T (TT genotype) mutations with myocardial infarction, ischemic stroke, or peripheral vascular disease. Studies were included only when they adhered to specific diagnostic criteria for ischemic events and met the published methodological criteria. Odds ratios (ORs) with accompanying 95% CIs were calculated for each mutation and clinical end points with a random-effects model (DerSimonian and Laird method).

RESULTS

The association between inherited gene mutations and arterial ischemic events was modest: factor V Leiden mutation (OR, 1.21; 95% CI, 0.99-1.49), PT G20210A mutation (OR, 1.32; 95% CI, 1.03-1.69), and MTHFR TT mutation (OR, 1.20; 95% CI, 1.02-1.41). Subgroup analyses of younger patients (<55 years old) and of women revealed slightly stronger associations overall.

CONCLUSIONS

Genetic abnormalities specific to factor V, prothrombin,and homocysteine metabolism increase the risk for myocardial infarction and ischemic stroke, particularly among younger patients and women. Because the overall association is only modest, screening studies should be limited to carefully selected patient populations. The individual propensity for arterial and venous thrombosis is likely influenced by differing local mechanisms, systemic mechanisms, or both.

Laboratory evaluation of hypercoagulability with venous or arterial thrombosis

OBJECTIVE

To provide recommendations for hypercoagulation testing for patients with venous, arterial, or neurovascular thrombosis, as reflected in the medical literature and the consensus opinion of recognized experts in the field.

DATA SOURCES, EXTRACTION, AND SYNTHESIS

The authors extensively examined the literature and current practices, and prepared a draft manuscript with preliminary recommendations. The draft manuscript was circulated to each of the expert participants (n = 30) in the consensus conference prior to the convening of the conference. The manuscript and recommendations were then presented at the conference for discussion. Recommendations were accepted if a consensus of the 28 experts attending the conference was reached. The discussions were also used to revise the manuscript into its final form.

CONCLUSIONS

The resulting article provides 17 recommendations for hypercoagulation testing in the setting of venous, arterial, or neurovascular thrombosis. The supporting evidence for test selection is analyzed and cited, and consensus recommendations for test selection are presented. Issues for which a consensus was not reached at the conference are also discussed.

The role of prothrombotic mutations in patients with Buerger's disease

Thromboangiitis obliterans (TAO), or Buerger's disease, is a segmental occlusive inflammatory disorder of the arteries and veins, and etiopathogenesis is still obscure. In the present study we investigated the prevalence of prothrombin 20210 G-->A, factor V 1691 G-->A (Factor V Leiden), and factor V 4070 A-->G (His 1299 Arg) mutations, found to be associated with increased risk for vascular thrombosis, in 36 patients with TAO. We performed a case-control study of these mutations. The odds ratio for prothrombin 20210 A allele compared with G allele was 7.98 (95% confidence intervals 2. 45-25.93). Only this prothrombotic genetic factor was associated with the risk of TAO (p=0.032). In conclusion, carrying the prothrombin 20210 G-->A may be an important prothrombotic risk factor of TAO. This genetic predisposition must be screened in these patients routinely, and clinical importance must be supported by further investigations.