G20210A prothrombin gene polymorphism and prothrombin activity in subjects with or without angiographically documented coronary artery disease

Risk factors profile of young and older patients with myocardial infarction

Myocardial infarction (MI) among young adults (<45 years) represents a considerable proportion of the total heart attack incidents. The underlying pathophysiologic characteristics, atherosclerotic plaque features, and risk factors profile differ between young and older patients with MI. This review article discusses the main differences between the younger and elderly MI patients as well as the different pathogenic mechanisms underlying the development of MI in the younger. Young patients with MI often have eccentric atherosclerotic plaques with inflammatory features but fewer lesions, and are more likely to be smokers, obese, and have poor lifestyle, such as inactivity and alcohol intake. Compared to older MI patients, younger are more likely to be men, have familial-combined hyperlipidaemia and increased levels of lipoprotein-a. In addition, MI in younger patients may be related to use of cannabis, cocaine use, and androgenic anabolic steroids. Genomic differences especially in the pathways of coagulation and lipid metabolism have also been identified between young and older patients with MI. Better understanding of the risk factors and the anatomic and pathophysiologic processes in young adults can improve MI prevention and treatment strategies in this patient group. Awareness could help identify young subjects at increased risk and guide primary prevention strategies. Additional studies focusing on gene pathways related to lipid metabolism, inflammation, and coagulation are needed.

[Acute coronary syndrome in a young female patient: findings beyond coronary lesions]

Nous exposons le cas d’une patiente de 47 ans qui présente un syndrome coronarien aigu et une probable embolie artérielle du membre inférieur droit dans l’étude duquel nous détectons la présence de la mutation du gène de la prothrombine G201210A associée à la présence de facteur anticoagulant lupique. La patiente a bénéficié d’une transplantation cardiaque avec bonne évolution clinique.

Prothrombin G20210A (rs1799963) polymorphism increases myocardial infarction risk in an age-related manner: A systematic review and meta-analysis

G20210A polymorphism (rs1799963) within the prothrombin gene is associated with a higher circulation level of prothrombin, thus increasing the likelihood of developing myocardial infarction (MI). Opinions differ regarding the correlation between prothrombin G20210A genotype and MI risk, which prompted us to conduct a meta-analysis to determine this association. PubMed, EMBASE, Web of Science and CNKI were searched for pertinent reports. A total of 34 studies involving 14 611 MI cases and 84 358 controls were analyzed in this quantitative analysis. We found a statistically significant association between prothrombin G20210A polymorphism and MI in the allele model (A vs. G, OR = 1.43, 95%CI: 1.18–1.72), heterozygote model (GA vs. GG, OR = 1.41, 95%CI: 1.16–1.72) and dominant model (GA + AA vs. GG, OR = 1.41, 95%CI: 1.15–1.72). The association remains significant in Caucasians but not in non-Caucasians. Moreover, prothrombin G20210A polymorphism increases MI risk in an age-related manner. A further significant association was found in a subpopulation younger than 55 years (allele model, OR = 1.76, 95%CI: 1.32–2.35; heterozygote model, OR = 1.70, 95%CI: 1.24–2.33; dominant model, OR = 1.70, 95%CI: 1.24–2.34). Sensitivity analysis and publication bias analysis revealed stable and statistically robust results. Our meta-analysis demonstrated that prothrombin G20210A polymorphism may represent a risk factor for MI.

Prothrombin Complex Concentrates for Bleeding in the Perioperative Setting

Prothrombin complex concentrates (PCCs) contain vitamin K-dependent clotting factors (II, VII, IX, and X) and are marketed as 3 or 4 factor-PCC formulations depending on the concentrations of factor VII. PCCs rapidly restore deficient coagulation factor concentrations to achieve hemostasis, but like with all procoagulants, the effect is balanced against thromboembolic risk. The latter is dependent on both the dose of PCCs and the individual patient prothrombotic predisposition. PCCs are approved by the US Food and Drug Administration for the reversal of vitamin K antagonists in the setting of coagulopathy or bleeding and, therefore, can be administered when urgent surgery is required in patients taking warfarin. However, there is growing experience with the off-label use of PCCs to treat patients with surgical coagulopathic bleeding. Despite their increasing use, there are limited prospective data related to the safety, efficacy, and dosing of PCCs for this indication. PCC administration in the perioperative setting may be tailored to the individual patient based on the laboratory and clinical variables, including point-of-care coagulation testing, to balance hemostatic benefits while minimizing the prothrombotic risk. Importantly, in patients with perioperative bleeding, other considerations should include treating additional sources of coagulopathy such as hypofibrinogenemia, thrombocytopenia, and platelet disorders or surgical sources of bleeding. Thromboembolic risk from excessive PCC dosing may be present well into the postoperative period after hemostasis is achieved owing to the relatively long half-life of prothrombin (factor II, 60-72 hours). The integration of PCCs into comprehensive perioperative coagulation treatment algorithms for refractory bleeding is increasingly reported, but further studies are needed to better evaluate the safe and effective administration of these factor concentrates.

Association Between the G20210A Polymorphism of Prothrombin Gene and Myocardial Infarction in Tunisian Population

The prothrombin is the precursor of the serine protease thrombin, a key enzyme in homeostasis. Prothrombin G20210A polymorphism (rs1799963) was described as a moderate risk factor for venous thrombosis because this mutation is associated with prothrombin elevated levels which may lead to an imbalance between the procoagulant, anticoagulant, and fibrinolytic system. 20210A carriers have an increased risk of thrombosis. In this study, we proposed to determine the prevalence of 20210A prothrombin variant among Tunisian population, and to evaluate the potential relevance of this variant with myocardial infarction. This study included 1290 unrelated Tunisians (1007 male and 283 female) divided in two groups: Four hundred and eighty-seven MI patients (mean age: 52.64 ± 8.98 years) and 803 apparently healthy controls (mean age: 51 ± 8.99). The prothrombin G20210A polymorphism was carried out by polymerase chain reaction/restriction fragment length polymorphism (PCR-RFLP) analysis. The distribution of genotypes was in accordance with Hardy-Weinberg equilibrium (p > 0.05). A significant difference in genotype distribution and allele frequency was observed between patients and controls. Male patients with MI had a frequency of 97 % for GG genotype and 3 % for GA+AA genotypes. The control group had a frequency of 99 % for the GG genotype and 1 % for the GA+AA genotypes which is significantly lower than the frequency found in patients (p = 0.01). The same genotype frequencies were found in women (p = 0.032). The MI patient group showed a significantly higher frequency of 20210A allele compared to controls 0.02 versus 0.01 [OR = 3.60 (95 % CI = 1.29-10.53), p = 0.005] in men and 0.015 versus 0.068 [OR = 4.68 (95 % CI = 1.60-14.26), p = 0.001] in women. Our work showed a significant but not independent association between the G20210A polymorphism of the prothrombin gene and MI in the Tunisian population.

Factor II activity is similarly increased in patients with elevated apolipoprotein CIII and in carriers of the factor II 20210A allele

Background

Few studies have so far investigated the relationship between apolipoprotein CIII (Apo CIII) and coagulation pathway in subjects with or without coronary artery disease (CAD).

Methods and Results

Serum Apo CIII concentrations and plasma coagulant activities of factor II (FII:c), factor V (FV:c), and factor VIII (FVIII:c), and activated factor VII (FVIIa) were analyzed in a total of 933 subjects, with (n=687) or without (n=246) angiographically demonstrated CAD and not taking anticoagulant drugs. Activated factor X (FXa) generation assay was performed on plasma from subgroups of subjects with low and high levels of Apo CIII. A statistical incremental concentration of FII:c, FV:c, and FVIIa levels was observed through the quartiles of Apo CIII distribution in the population considered as a whole. Significant results were confirmed for FII:c in CAD and CAD‐free subgroup when separately considered. Subjects within the highest Apo CIII quartile (>12.6 mg/dL) had high FII:c levels not statistically different from those of carriers of 20210A allele (n=40; 4.28%). In a multiple linear model, Apo CIII was the best predictor of FII:c variability, after adjustment for age, gender, plasma lipids, CRP, creatinine, diagnosis, and carriership of 20210A allele. FXa generation was increased and its lag time shortened in plasmas with high Apo CIII levels. However, after thrombin inhibition by hirudin, differences between low and high Apo C‐III samples disappeared.

Conclusions

Elevated concentrations of Apo CIII are associated with an increase of thrombin activity to an extent comparable with the carriership of G20210A gene variant and mainly modulating the thrombin generation.

Polymorphisms in Factor II and Factor V thrombophilia genes among Circassians in Jordan

Thrombosis is a major cause of morbidity and mortality worldwide. Genetic factors are one component of thrombosis. We studied the prevalence of two mutations that are known risk factors in the pathogenesis of arterial and venous thrombosis in the genetically isolated Circassian population in Jordan. Factor II G20210A and Factor V Leiden single nucleotide polymorphisms were analysed by polymerase chain reaction and restriction fragment length polymorphism method in 104 random unrelated subjects from the Circassian population in Jordan. The prevalence rates among the Circassian population in Jordan for Factor II G20210A was 12.2% and for Factor V Leiden was 7.7%. We have shown that the population is in Hardy-Weinberg equilibrium and that the prevalences of both mutations are within the range of other ethnic groups. This is the first study to describe Circassian health related genetic characteristics in Jordan. Such population-based studies will contribute to understanding the interaction between genetic and environmental risk factors. It will remain to be seen whether carriers of Factor II G20210A and Factor V Leiden are more likely to develop thrombosis. This issue should be studied in the future to determine the need for screening of these mutations particularly in thrombophilia patients.

Analysis of polymorphisms Leiden Factor V G1691A and prothrombin G20210A as risk factors for acute myocardial infarction

Thrombotic risk increases in elderly, therefore, the understanding of the genetic predisposition of hypercoagulability could make the difference in the prevention of venous and/or arterial thrombotic events. Laboratory evaluation of hyperfibrinogenemia, increased Factor VII levels, antiphospholipid antibodies presence and hyperhomocysteinemia are considered to have a consistent high predictivity for arterial thrombophilic diseases. Anyway, a large debate exists on the validity of testing Leiden Factor V (FV) G1691A and/or prothrombin (FII) G20210A polymorphisms in patients affected by arterial thrombotic diseases, despite of the several observations described. Here we report data strongly suggesting that at least the FII G20210A polymorphism might be considered an important risk factor for acute myocardial infarction in aged patients (55-80 years old). On the other hand, in spite of a not different genotypic and allelic distribution for the Leiden FV G1691A mutation, the presence of one or both the two polymorphisms is significantly higher among cases than in controls. In conclusion, our data suggest that FII G20210A and/or Leiden FV might be involved as risk factor for arterial disorders in about 5% of old subjects, justifying the opportunity of a genetic screening and an eventual preventive treatment, in particular in old subjects in which other and major risk factors, as hypertension and atherosclerosis, are detected.

Genetic polymorphisms and atrial fibrillation: Insights into the prothrombotic state and thromboembolic risk

The pathophysiology of thromboembolism in atrial fibrillation (AF) is a multifactorial and complex process. Abnormalities of haemostasis, fibrinolysis, endothelium, and platelets have all been described in AF. This prothrombotic state observed in AF appears to be additive to the presence of clinical and echocardiography risk factors for thromboembolism. Nonetheless, the precise mechanistic pathway(s) leading to the prothrombotic state in AF remain to be elucidated. Of note, there are limited data on the influence of genetic polymorphisms in thromboembolic risk associated with AF. On the other hand, the response to coumarin derivatives depends on several factors, such as sex, age, diet, or interacting drugs. Optimal anticoagulation control is usually hampered by significant interindividual variability in dose requirements for a given target level of anticoagulation. There is increasing evidence that interindividual sensitivity and side-effects to coumarinics may be largely determined genetically. Thus, genetic polymorphisms could explain the individual risk of developing an adverse drug reaction (bleeding) or drug inefficacy (thrombosis) with oral anticoagulation. In this article, we provide an overview of the limited data about the possible influence of genetic polymorphisms on thromboembolic risk in AF, as well as the genetic influences on anticoagulant drug responsiveness.

Varied association of prothrombin G20210A polymorphism with coronary artery disease susceptibility in different ethnic groups: evidence from 15,041 cases and 21,507 controls

Published data on the association between prothrombin G20210A polymorphism and coronary artery disease (CAD) risk are inconclusive. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 42 case-control studies including 15,041 cases and 21,507 controls were included in this meta-analysis. Overall, significantly elevated CAD risk was associated with prothrombin G20210A polymorphism (OR, 1.22; 95% CI 1.07-1.40; P=0.003) when 39 eligible studies were pooled into the meta-analysis. In the subgroup analysis, borderline statistically increased risk was found for myocardial infarction in 22 case-control studies (OR, 1.27; 95% CI 1.00-1.61; P=0.05). When stratified by ethnicity, significantly elevated risk was found in Europeans (OR, 1.19; 95% CI, 1.02-1.38; P=0.02). However, no statistical differences were found among Americans and Asians. In summary, this meta-analysis indicated that prothrombin G20210A allele is a low-penetrant risk factor for developing CAD in Europeans.

The factor V G1691A, factor V H1299R, prothrombin G20210A polymorphisms in children with family history of premature coronary artery disease

Atherosclerosis, the major cause of coronary artery disease (CAD), has a very long asymptomatic development phase, which begins in childhood. In this study, we describe the factor V G1691A, factor V H1299R and prothrombin G20210A gene polymorphisms in children with a family history of premature CAD. Evidence of these polymorphisms in these children may predict the probability of having atherosclerosis in the future. Our study included a total of 140 children, 72 males and 68 females between the ages of 4.9 and 15.7 years. Among these children, 73 had a parental history of premature CAD and the remaining 67 belonged to our control group. The participants were screened for the mutations factor V G1691A, factor V H1299R and prothrombin G20210A by polymerase chain reaction amplified DNA products with specific oligonucleotide probes. Our results suggested that frequencies of the mutated allele of factor V G1691A and prothrombin G20210A are higher in children with a parental history of premature CAD. In conclusion, factor V G1691A and prothrombin G20210A polymorphisms which were detected in higher frequencies in children with a parental history of premature CAD may indicate a risk for developing atherosclerosis and might be useful in screening for CAD in children; however, large population-based research is necessary to investigate further genetic risk assessment for CAD.

Prothrombin gene G20210A mutation in acute deep venous thrombosis patients with poor response to warfarin therapy

AIM

The pathogenesis of deep venous thrombosis (DVT) involves an interaction between hereditary and acquired factors. Prothrombin gene mutation is one of the hereditary risk factors. We evaluated the frequency of the prothrombin gene mutation in patients with DVT and its relation to oral warfarin anticoagulant therapy response.

METHODS

Prothrombin gene mutation was looked for in 40 DVT patients with poor response to warfarin. The results were compared with 40 DVT patients with a normal response to warfarin and 30 healthy blood donors. Blood samples were also assessed for protein C, protein S, anti-thrombin III and anticardiolipin antibodies (ACA) levels.

RESULTS

Prothrombin gene mutation was found in normal and poor DVT responders (6/40 and 13/40, respectively; p = NS) as well as in healthy controls (1/30). Patients with recurrent DVT or a family history of DVT were significantly (p<0.0001) more likely to have the prothrombin mutation than other DVT patients. Non prothrombin abnormalities (protein C, anti-thrombin III and ACA) were more common in poor responders than controls (p<0.0037) as were ACA (p<0.034).

CONCLUSIONS

Prothrombin gene mutation is present in several DVT patients, especially those with recurrent DVT or a family history of DVT. This mutation may contribute to a poor response to warfarin.

Gene polymorphisms in APOE, NOS3, and LIPC genes may be risk factors for cardiac adverse events after primary CABG

Introduction

Coronary artery disease progression after primary coronary artery bypass grafting may, beside classical atherosclerosis risk factors, be depending on genetic predisposition.

Methods

We investigated 192 CABG patients (18% female, age: 60.9 ± 7.4 years). Clinically cardiac adverse events were defined as need for reoperation (n = 88; 46%), reintervention (n = 58; 30%), or angina (n = 89; 46%). Mean follow-up time measured 10.1 ± 5.1 years. Gene polymorphisms (ApoE, NOS3, LIPC, CETP, SERPINE-1, Prothrombin) were investigated separately and combined (gene risk profile).

Results

Among classical risk factors, arterial hypertension and hypercholesterinemia significantly influenced CAD progression. Single ApoE, NOS3 and LIPC polymorphisms provided limited information. Patients missing the most common ApoE ε3 allele (5,2%), showed recurrent symptoms (p = 0,077) and had more frequently reintervention (p = 0,001). NOS3 a allele was associated with a significant increase for reintervention (p = 0,041) and recurrent symptoms (p = 0,042).

Homozygous LIPC patients had a higher reoperation rate (p = 0.049).

A gene risk profile enabled us to discriminate between faster and slower occurrence of cardiac adverse events (p = 0.0012).

Conclusion

Single APOE, LIPC and NOS3 polymorphisms permitted limited prognosis of cardiac adverse events in patients after CABG. Risk profile, in contrast, allowed for risk stratification.

Factor VLeiden and prothrombin G20210A gene polymorphisms in patients with coronary artery disease

PURPOSE

The precise molecular mechanisms culminating in coronary artery disease (CAD) are not well understood, despite a wealth of knowledge on predisposing risk factors and pathomechanisms. CAD and myocardial infarction (MI) are complex genetic diseases; neither the environment alone, nor a single gene, cause disease, rather, a mix of environmental and genetic factors lead to atherosclerosis of the coronary arteries.

MATERIALS AND METHODS

In the present study, our aim was to investigate the roles of prothrombin G20210A mutation and Factor VLeiden mutation in atherosclerotic coronary artery disease. 287 subjects (106 control subjects, who were angiographically normal, and 181 angiographically documented coronary atherosclerotic patients who exhibited coronary artery narrowing to a degree of >or=50%) were included in this study. The mutations were assessed with LightCycler Real-Time PCR mutation detection kits (Roche Diagnostics, GmbH, Germany).

RESULTS

6.6% of control subjects, and 6.1% of patients with (50% coronary artery narrowing were determined to have the Factor VLeiden heterozygote mutation. 6.6% of control subjects had the Prothrombin G20210A heterozygote mutation, while 7.7% of patients with (50% coronary artery narrowing had this mutation. The OR for Factor VLeiden was 1.52 (CI: 0.240-9.602) and for Prothrombin G20210A mutation, the OR was 1.415 (CI: 0.287-6.962).

CONCLUSION

Although both the heterozygote Factor VLeiden and Prothrombin gene mutations were more frequent in patients with CAD than in control subjects, there was no statistical relationship found to exist between coronary artery disease and the Factor VLeiden and Prothrombin G20210A mutations.

Involvement of -308 TNF-alpha and 1267 Hsp70-2 polymorphisms and zinc status in the susceptibility of coronary artery disease (CAD) in old patients

Coronary artery disease (CAD) is characterized by an inflammatory status and it represents the major cause of death in elderly. Zinc deficiency and inflammatory genes within major histocompatibility complex (MHC) region are implicated in ischaemic heart diseases. TNF-alpha is present in coronary artery plaques and may provoke plaque instability. Hsp70 plays instead a pro-atherogenic role, via proinflammatory cytokine production, in atherosclerotic lesions contributing to plaque rupture. Contradictory data report the association between -308 TNF-alpha polymorphism and CAD, while no investigations exist on Hsp70-2 gene in CAD. In the current study, we analysed -308 TNF-alpha and 1267 Hsp70-2 polymorphisms and zinc status in 190 healthy old controls and 216 old patients with carotid stenosis subdivided in two groups: the first one 105 patients with CAD (C group), and the second one 111 patients without cardiovascular events (D group). We found a lack of association between -308 TNF-alpha polymorphism and CAD. Conversely, 1267 Hsp70-2 polymorphism was associated with CAD. In particular, significant higher frequency of AB + BB genotypes (B + genotype) was observed in C patients than controls (71.4 vs.56.9%, P = 0.017, odds ratio = 1.898). However, when C patients were subdivided into four subgroups on the basis of presence/absence of 1267B Hsp70-2 and -308A TNF-alpha alleles, B + A + patients showed higher prothrombin activity as well as Hsp70-2, TNF-alpha, IL-6 gene expressions in carotid atheroma when compared to B - A - genotypes. The zinc status (plasma and Zn/Fe ratio in erythrocytes) is not affected by these polymorphisms. However, zinc deficiency is present in CAD condition. In conclusion, 1267 HSP70-2 polymorphism and zinc deficiency, rather than -308 TNF-alpha, are independently associated with CAD. B + A+ and B + A- carriers seem more predisposed to ischaemic events; conversely, B - A- genotype may be considered a protective marker against CAD.

G20210A Prothrombin gene variant in Turkish patients with angiographically documented coronary artery disease

BACKGROUND

G-->A substitution at position 20210A in the 3'-untranslated region in prothrombin gene is associated with raised plasma prothrombin. G20210A prothrombin variant has been associated with high prothrombin levels and an increased risk of venous thrombosis. To determine the prevalence of the G20210A prothrombin variant among Turkish and to evaluate the potential relevance of this variant to Turkish patients with angiographically documented coronary artery disease (CAD).

METHODS

We conducted a case-control study on 268 unrelated subjects who referred to the cardiology department of the university hospital for coronary angiography. One hundred-thirty seven patients with angiographically documented CAD and 131 subjects without angiographically documented CAD were studied to examine the association of the G20210A prothrombin variant with CAD. Blood samples from the patients and controls were analyzed for the G20210A prothrombin variant by DNA analysis, using polimeraz chain reaction.

RESULTS

G20210A prothrombin variant was found in 6 of 137 (4.4%) patients with CAD and 1 of 131 (0.8%) in control subjects (p = 0.064). There were no significant differences in terms of diabetes mellitus, hypertension, dyslipidemia, sex and family history of CAD with and without the G20210A prothrombin variant in the patient group.

CONCLUSIONS

In agreement with the results of recent meta-analyses, our data from northeast Anatolia show a 5-fold higher prevalence of the G20210A prothrombin variant among the patients with angiographically-documented CAD when compared with those without angiographic signs of significant CAD and its variant cannot be considered as a risk factor for CAD in this region.

Prevalence of normal coronary angiography in the acute phase of suspected ST-elevation myocardial infarction: experience from the PRAGUE studies

BACKGROUND

Acute ST-elevation myocardial infarction in patients with normal coronary arteries has previously been described, but coronary angiography in these patients was performed after the acute phase of the infarction. It is possible that these patients did not have normal angiograms during the acute phase (transient coronary thrombosis or spasm were usually suspected to be the cause). Information on the prevalence of truly normal coronary angiograms during the acute phase of a suspected ST-elevation myocardial infarction is lacking.

PATIENTS AND METHODS

The Primary Angioplasty in patients transferred from General community hospitals to specialized PTCA Units with or without Emergency thrombolysis-1 (PRAGUE-1) and PRAGUE-2 studies enrolled 1150 patients with ST-elevation acute myocardial infarction, in whom 625 coronary angiograms were performed within 2 h of the initial electrocardiogram. A simultaneous registry included an additional 379 coronary angiograms performed during the ST-elevation phase of a suspected myocardial infarction. Thus, a total of 1004 angiograms were retrospectively analyzed. A normal coronary angiogram was defined as one with the absence of any visible angiographic signs of atherosclerosis, thrombosis or spontaneous spasm.

RESULTS

Normal coronary angiograms were obtained for 26 patients (2.6%). Among these, the diagnosis at discharge was a small myocardial infarction in seven patients (0.7%), acute (peri)myocarditis in five patients, dilated cardiomyopathy in four patients, hypertension with left ventricular hypertrophy in three patients, pulmonary embolism in two patients and misinterpretation of the electrocardiogram (ie, no cardiac disease) in five patients. Seven patients with small infarctions underwent angiography within 30 min to 90 min of complete relief of the signs of acute ischemia, and thus, angiograms during pain were not taken. None of the 898 patients catheterized during ongoing symptoms of ischemia had a normal coronary angiogram. Spontaneous coronary spasm as the only cause (without underlying coronary atherosclerosis) for the evolving infarction was not seen among these 898 patients. Thus, the causes of the seven small infarcts in patients with normal angiograms remain uncertain.

CONCLUSIONS

The observed prevalence of normal coronary angiography in patients presenting with acute chest pain and ST elevations was 2.6%. Most of these cases were misdiagnoses, not infarctions. A normal angiogram during a biochemically confirmed infarction is extremely rare (0.7%) and was not seen during the ongoing symptoms of ischemia.

Acute myocardial infarction following an arthropod bite: is hereditary thrombophilia a contributing factor?

Acute myocardial infarction (AMI) due to arthropod envenomation has rarely been reported in the literature. In the present report, we describe two cases who developed AMI following an arthropod bite. Coronary angiograms revealed normal coronary arteries in both patients. Both events were probably secondary to coronary artery thrombosis and/or coronary artery vasospasm. Both patients were subsequently found to be heterozygous for prothrombin mutation (G20210A). As a result, we recommend ruling out the possibility of hereditary thrombophilias in young patients with AMI developing after an arthropod bite.

Gene polymorphisms in patients below 35 years of age who underwent coronary artery bypass surgery

OBJECTIVE

Genetic bases for novel prothrombotic, inflammatory risk factors may play a role in the early onset of coronary artery disease.

METHODS

Twenty-one patients below 35 years of age who underwent coronary bypass grafting between 2002 and 2004 constituted the study group and were compared with 50 healthy, age and sex-matched controls. Gene analysis for genetic polymorphisms of angiotensin-converting enzyme, prothrombin G20210A, tumour necrosis factor-alpha G308A, factor V Leiden and interleukin-6 genes was carried out.

RESULTS

The control group was 98% homozygous for the factor V Leiden GG allele and 2% heterozygous for the GA allele. On the other hand, the study group was 76.2% homozygous for the GG allele, and 23.8% heterozygous for the GA allele (P<0.05). Homozygosity for factor V Leiden mutation (AA) was not encountered in either group. With regard to interleukin-6, 70.0% of the control group demonstrated homozygosity for the GG allele and 30.0% showed heterozygosity (GC). The study group was 52.4% homozygous for the GG allele and heterogenicity was similar in this group (28.6% GC). On the other hand, 19.0% of this group demonstrated CC homogenicity (P<0.05). No difference was observed with regard to gene polymorphisms.

CONCLUSIONS

Gene polymorphisms with regard to prothrombotic factor V Leiden mutation and inflammatory marker interleukin-6 may play a role in the pathogenesis of early-onset coronary artery stenosis in patients below 35 years of age.

The role of genetics in the risk of thromboembolism: prothrombin 20210A and oral contraceptive therapy

PURPOSE

To provide an overview of the prothrombin 20210A mutation, its effects on the incidence of venous thromboembolism (VTE) in users of oral contraceptive therapy (OCT), and screening recommendations for the primary care practice setting.

DATA SOURCES

Several databases, including MEDLINE, EMBASE, BIOSIS, Cochrane Library, and SciSearch, were searched for articles published between 1996 and 2003. An integrative review of studies addressing prothrombin 20210A was done using available case-series and case-control studies. No randomized controlled trials on prothrombin 20210A were available in the literature from the years searched.

CONCLUSIONS

Prothrombin 20210A increases the risk of developing a VTE for those who carry the genetic mutation. The presence of either concomitant circumstantial factors (e.g., surgery or immobilization) or a combination of genetic factors (e.g., factor V Leiden and prothrombin 20210A) raises the frequency of VTEs to an even greater extent. The risk increases exponentially in users of OCT. Screening guidelines for the use of OCT in prothrombin 20210A carriers remain unclear due to the paucity of empirical evidence related to the topic.

IMPLICATIONS FOR PRACTICE

Practitioners caring for a prothrombin 20210A carrier should maintain a high degree of suspicion with even vague signs or symptoms of a possible VTE. Practitioners should consider completing a full diagnostic workup for VTE on that patient, particularly if that patient is taking OCT. Until evidence becomes available as to the best anticoagulation practice after an initial or recurrent VTE in a prothrombin 20210A carrier, standard treatment guidelines for anticoagulation should be followed.

G20210A is a functional mutation in the prothrombin gene; effect on protein levels and 3'-end formation

BACKGROUND

The prothrombin G20210A mutation is associated with increased plasma prothrombin levels and risk of thrombosis. The mechanism by which this mutation leads to increased prothrombin expression is as yet unclear and still the subject of debate.

OBJECTIVES

The aim of this study was to investigate the effect of the G20210A mutation on mRNA and protein expression.

METHODS

We made a set of constructs containing the prothrombin 5'-regulatory region, the firefly luciferase reporter gene and the prothrombin 3'-UTR+ downstream region. The latter element contained either the 20210G or A allele and was inserted either as a single unit (constructs G1 and A1) or in tandem (A1A2, G1G2, A1G2, G1A2). Constructs were transiently expressed in HepG2 cells. Expression was evaluated by luciferase assays and reverse transcriptase-polymerase chain reaction (RT-PCR), followed by quantification of the products and determination of the ratio of poly(A)site usage. RT-PCR sequencing was used for determination of the actual site of polyadenylation in mRNAs from constructs G1 and A1 and from endogenous prothrombin mRNAs from HepG2 cells and human liver tissue.

RESULTS

The A1 constructs expressed 1.2-fold more protein than the G1 constructs. The double constructs expressed 1.4-fold more protein (A1A2 vs. G1G2). Similar results were found in a set of constructs in which an SV40 promoter replaced the prothrombin 5'-regulatory region. Ratios of poly(A) site usage (expressed as ratio poly(A) site 1 and 2) for the tandem constructs were similar for constructs with two Gs or As at both poly(A)sites; 2.92 (95% confidence interval 2.39-3.45) and 2.75 (2.55-2.95). pA1/pA2 ratios were 1.46 (1.11-1.81) for G1A2 and 6.29 (5.48-7.10) for A1G2 constructs with different poly(A) sites, indicating that the poly(A)site with the 20210A variant is favored over the normal site. In 20210G mRNAs, the G at 20210 was the last non-A nucleotide in the majority of mRNAs, whereas in most 20210A mRNAs, the last non-A nucleotide was the C at 20209. Over 70% of the prothrombin 20210G mRNAs from HepG2 cells and human liver tissue is polyadenylated at position 20210.

CONCLUSIONS

The 20210A variant has a more effective poly(A) site, leading to increased mRNA and protein expression, irrespective of the promoter and gene. It does not affect the position of poly(A) attachment.

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.

Combined carrier status of prothrombin 20210A and factor XIII-A Leu34 alleles as a strong risk factor for myocardial infarction: evidence of a gene-gene interaction

Studies associating the prothrombin 20210G>A (FII 20210A), factor V Leiden (FVL), and factor XIII Leu34 (FXIII-A Leu34) alleles with myocardial infarction (MI) have yielded conflicting results. Complicated gene-gene interactions, small sample sizes, and heterogeneous genetic and environmental backgrounds may contribute to opposing findings. Simultaneous analysis of multiple gene variants in a large sample size from a genetically isolated population may overcome these weaknesses. Genotyping was performed in 500 MI patients and 500 control subjects from the genetically isolated Newfoundland population to determine the prevalence of the FII 20210A, FVL, and FXIII-A Leu34 variants and their association with MI. Gene-gene interactions were also analyzed. The prevalence of the FII 20210A allele was higher in MI patients (3.2%) than in control subjects (1.0%; P =.015). The FII 20210A allele was also 5.6-fold higher in MI patients younger than 51 years than in age-matched control subjects (P =.04). FVL showed 3.9-fold higher prevalence in young patients than in patients older than 50 years (P =.004) and 2.7-fold higher than in age-matched control subjects (P =.007). Furthermore, the prevalence of combined carriers of the FXIII-A L34 and FII 20210A alleles was 12-fold higher in MI patients than in control subjects (P =.002) and with 92% penetrance. There was disequilibrium of the FXIII-A Leu34 allele to MI patients carrying the FII 20210A allele as a genetic background. Based on our data, we determined that (1) the FII 20210A allele is a risk factor for MI, possibly important for early onset; (2) FVL may predispose for early-onset MI; (3) the FXIII-A Leu34 allele predisposes for MI in males only; however, (4) interaction between the FII 20210A and FXIII-A Leu34 alleles forms a synergistic coeffect that strongly predisposes for MI, placing combined carriers at high risk for MI.

Prospective study of the G20210A polymorphism in the prothrombin gene, plasma prothrombin concentration, and incidence of venous thromboembolism

Case-control studies have indicated increased risk of venous thrombosis associated with the prothrombin gene G20210A polymorphism and with elevated plasma prothrombin levels. We sought to confirm these results in a prospective population-based study of 21,690 persons. We measured G20210A and prothrombin antigen on pre-event blood samples of 302 participants who developed venous thromboembolism (VTE) and 626 participants who remained free of VTE. Approximately 4.0% of cases and 2.4% of controls carried the G20210A polymorphism, but only one of 137 African Americans did. The odds ratio in whites was 1.87 (95% CI = 0.85, 4.11)--higher for those who reported a prior history of VTE (OR = 5.44) than those reporting no VTE history (OR = 1.41) and in those with idiopathic VTE (OR = 2.51) than those with secondary VTE (OR = 1.38). There was no association between venous thromboembolism and plasma prothrombin antigen level. We estimated that the G20210A polymorphism may account for approximately 2.5% of venous thromboembolism events in United States whites.

Prevalence of the 20210 G-->A prothrombin variant and its association with coronary artery disease in a Middle Eastern Arab population

BACKGROUND

No reports are available on the distribution of the 20210 G-->A prothrombin variant among Middle Eastern Arabs. Additionally, to date, studies that attempt to establish this polymorphism as an independent risk factor or as a predictor for coronary artery disease (CAD) have yielded conflicting results.

OBJECTIVE

To determine the prevalence of the 20210 G-->A prothrombin variant among Middle Eastern Arabs and to evaluate the potential relevance of this variant to Arab patients with angiographically documented CAD.

METHODS AND RESULTS

We used the polymerase chain reaction and restriction enzyme digestion to determine the prevalence of this polymorphism in 613 individuals from Arabic ethnic origin with CAD and from 593 healthy blood donors (BDs) from an identical ethnic background. Within the BD group (n = 593), 10 individuals (1.7%) were heterozygous, 583 individuals (98.3%) were normal, and none were homozygous for the 20210 G-->A prothrombin variant. Within the CAD group (n = 613), 13 individuals (2.1%) were heterozygous, 600 individuals (97.9%) were normal, and none were homozygous for the 20210 G-->A prothrombin variant. A chi(2) analysis was used to evaluate any significance in the distribution of genotypes. A value of 1.23 was obtained. Values less than 3.84 indicate no statistically significant difference between the heterozygous carriers of the 20210A allele in both study groups.

CONCLUSIONS

In our population of Middle Eastern Arabs, the presence of the 20210 G-->A prothrombin variant is not associated with patients with angiographically documented CAD. Therefore, this variant cannot be considered as an independent risk factor or as a predictor for CAD in this population.

Interaction of hemostatic genetics with hormone therapy: new insights to explain arterial thrombosis in postmenopausal women

Genetic variants of key hemostatic mediators increasingly have been proposed as risk factors for atherothrombosis. The Hormone and Estrogen/Progestin Replacement Study group recently reported that the initiation of estrogen replacement in postmenopausal women with known coronary heart disease is associated with an early increase in cardiovascular events. A putative genetic susceptibility factor has been proposed a potential mediator of this increased event risk. This review outlines the recent literature to support the premise for this important proposal. Genetic profiling has great potential to improve the safety and efficacy of individualized pharmacotherapy in postmenopausal women and other at-risk populations for the prevention of cardiovascular disease.