High prevalence of hyperhomocyst(e)inemia in patients with juvenile venous thrombosis

Successful Treatment of Massive Pulmonary Embolism with Rescue Fibrinolysis in Young Patient with Homocystinemia - Case Report

Pulmonary embolism (PE) is the most frequently missed diagnosis in the urgent clinical department with serious consequences. Patients with unprovoked PE have increased risk of recurrent PE. Approximately 5 to 8% of PE patients have inherited thrombophilias. A solated homocystinemia is a rare cause of unprovoked acute pulmonary embolism. Timely diagnosis and proper treatment can prevent complications, costs and mortality and provide patient better quality of life. We are presenting a 42-year-old woman was admitted to our emergency department with the first episode of severe dyspnea and chest pain. She had no history of previous cardiovascular or respiratory disease and no history of previous pulmonary embolism (PE) or deep vein thrombosis (DVT). Urgent echocardiography showed indirect signs of pulmonary embolism which was confirmed by the pulmonary artery CT angiography performed one day after the patient’s admission. After two days of heparin infusion, she developed a hemodynamic instability with cardiogenic shock and was treated successfully with fibrinolysis. After the clinical stabilization, she was put on the rivaroxaban therapy, which was recommended for additional six months. The thrombophilia profile was done two weeks after stopping the therapy with rivaroxaban. The thrombophilia panel came back positive for high levels of homocysteine (67 μmol/L), with other thrombophilia results within normal limits. The patient was stable during the follow-up period. Pulmonary embolism should be always suspected in younger patients with acute severe dyspnea even without provocable risk factors. High suspicion level and fast diagnosis are lifesaving. In younger patients presented with unprovoked pulmonary embolism, clinicians should consider inherited prothrombotic factors and homocystinemia as a potential cause. Rescue fibrinolysis is a lifesaving therapy in hemodynamic worsening in intermediate high-risk PE patients. A longer anticoagulation therapy should be considered in these cases with novel oral anticoagulants that are recommended as safer and superior therapy.

Serological Parameters and Vascular Investigation for a Better Assessment in DVT during Pregnancy-A Systematic Review

Pregnancy and the postpartum period represent a condition characterized by a thrombotic predisposition. The majority of pregnant women do not face acute or severe thrombotic events. In general, mild inconveniences such as leg swelling or moderately painful thrombotic events (phlebitis) are encountered. However, when pregnancy is associated with inherited or acquired deficits that affect homeostasis, the risk of acute or even life-threatening events can increase significantly. The major consequence is the loss of the fetus or the venous thromboembolism that endangers the mother's life. Venous thromboembolism is caused by deep vein thrombosis, therefore timely detection and especially the assessment of the extent of the thrombotic event are crucial. In this paper we have summarized the most important paraclinical investigations. The study emphasizes the importance of selecting the methods of investigation. The right choice allows establishing a correct diagnosis and individualizing the treatment.

Contribution of MTHFR gene variants in lupus related subclinical atherosclerosis

OBJECTIVE

Elevated concentrations of homocysteine have been previously identified as an independent risk factor for subclinical atherosclerosis in patients with systemic lupus erythematosus (SLE). Given that heightened homocysteine levels are known to be strongly influenced by genetic factors, in the current study we investigated the contribution of high homocysteine levels as well as of functional polymorphisms of the gene encoding for the enzyme 5, 10- methylenetetrahydrofolate reductase (MTHFR) to atherosclerotic disease characterizing SLE patients.

METHODS

Peripheral DNA samples from 150 SLE patients, 214 rheumatoid arthritis (RA) patients and 561 age/sex matched apparently healthy volunteers (HC) were genotyped by PCR-based assays for the detection of the MTHFR gene polymorphisms (c. 677C > T and c. 1298A > C). All SLE patients and 30 age sex matched RA patients underwent assessment for subclinical atherosclerosis [ultrasound measurement of intima-media thickness scores (IMT) and detection of carotid and/or femoral (C/F) plaque] and complete clinical and laboratory evaluation including serum homocysteine levels. Data were analyzed using univariate and multivariate models (SPSS 21.0).

RESULTS

Hyperhomocysteinemia was detected in 26.0% of SLE patients compared to 6.7% of age/sex matched RA controls (p = 0.02). Higher serum B12 levels and decreased frequency of the MTHFR 677TT variant in RA patients could potentially account for the observed differences between the groups. In SLE patients, both hyperhomocysteinemia and MTHFR 677TT genotype were identified as independent contributors for plaque formation, following adjustment for traditional cardiovascular risk factors and disease related features, including age, sex, BMI, cholesterol and triglyceride levels, presence of arterial hypertension, smoking (pack/years), disease duration and total steroid dose [OR 95% (CI): 5.8 (1.0-35.8) and 5.2 (1.1-24.0), respectively]. MTHFR 677TT genotype, but not hyperhomocysteinemia was also found to confer increased risk for arterial wall thickening, after the above confounders were taken into account [OR (95%) CI: 4.9 (1.2-20.6)].

CONCLUSIONS

Hyperhomocysteinemia and MTHFR 677TT genetic variant emerged as independent risk factors for subclinical atherosclerosis in SLE patients, implying genetic influences as potential contributors to the increased burden of atherosclerotic disease characterizing SLE.

Venous thromboembolism and hyperhomocysteinemia as first manifestation of pernicious anemia: a case series

BACKGROUND

Hyperhomocysteinemia has been suspected of favoring thrombosis. Several case-control studies and even a meta-analysis have confirmed a link between venous thrombosis and hyperhomocysteinemia. Homocysteine is due to genetic and acquired factors (poor diet in folate and vitamin B12, older age, renal impairment, thyroid diseases, and malignancies) induced by the intake and the concentrations of vitamin B9 or B12 in the majority of cases.

CASES PRESENTATION

We report the cases of four Moroccan patients who presented with acute vein thrombosis of different sites: a 34-year-old man, a 60-year-old man, a 58-year-old man, and a 47-year-old woman. All patients had a low level of cobalamin with marked hyperhomocysteinemia with normal serum and red cell folic acid. Venous thrombosis revealed pernicious anemia in all patients. Their low levels of cobalamin, atrophic gastritis, and positive results for gastric parietal cell antibodies confirmed the diagnosis of pernicious anemia. There was no evidence of immobilization, recent surgery, malignancy, antiphospholipid antibody, myeloproliferative disorder, or hormone replacement therapy. No deficiencies in protein C and protein S were detected; they had normal antithrombin III function and factor V Leiden; no prothrombin gene mutations were detected. Treatment included orally administered anticoagulation therapy and cobalamin supplementation. The outcome was favorable in all cases.

CONCLUSIONS

These reports demonstrate that pernicious anemia, on its own, can lead to hyperhomocysteinemia that is significant enough to lead to thrombosis. Understanding the molecular pathogenesis of the development of thrombosis in patients with hyperhomocysteinemia related to Biermer disease would help us to identify patients at risk and to treat them accordingly. The literature concerning the relationship between homocysteine and venous thrombosis is briefly reviewed.

Cardiovascular disease in systemic lupus erythematosus: A comprehensive update

Heightened rates of both cardiovascular (CV) events and subclinical atherosclerosis, documented by imaging and vascular function techniques are well established in systemic lupus erythematosus (SLE). While traditional CV factors such as smoking, dyslipidemia, diabetes mellitus (DM), hypertension, central obesity and hyperhomocysteinemia have been reported to be prevalent in lupus patients, they do not fully explain the high rates of ischemic events so far reported, implying that other factors inherent to disease itself could account for the enhanced risk, including disease duration, activity and chronicity, psychosocial factors, medications, genetic variants and altered immunological mechanisms. Though the exact pathogenesis of atherosclerosis in the setting of lupus remains ill defined, an imbalance between endothelial damage and atheroprotection seems to be a central event. Insults leading to endothelial damage in the setting of lupus include oxidized low density lipoprotein (oxLDL), autoantibodies against endothelial cells and phospholipids, type I interferons (IFN) and neutrophil extracellular traps (NETs) directly or through activation of type I IFN pathway. Increased oxidative stress, reduced levels of the normally antioxidant high density lipoprotein (HDL), increased levels of proinflammatory HDL (piHDL) and reduced paraoxonase activity have been related to increased oxLDL levels. On the other hand, impaired atheroprotective mechanisms in lupus include decreased capacity of endothelial repair-partly mediated by type I IFN- and dampened production of atheroprotective autoantibodies. In the present review, traditional and disease related risk factors for CV disease (CVD) in the setting of chronic autoimmune disorders with special focus on SLE will be discussed.

High Plasma Homocysteine: A Risk Factor for Arterial and Venous Thrombosis in Patients with Normal Coagulation Profiles

A high plasma homocysteine concentration is associated with premature vascular disease and thrombosis. The association between high homocysteine concentrations and thrombosis in patients with a normal coagulation profile is unknown. Sixty adults (37 men and 23 women, mean age 46 years) with documented thrombosis were compared with age-and sex-matched controls. Those with risk factors for thrombosis or abnormal coagulation profiles were excluded. Homocysteine concentrations were higher in cases than controls (21.8 ± 13.8 vs 11.0 ± 4.7 μmol/L, p < 0.001). A cut point for defining high homocysteine concentrations was determined at 13 μmol/L and conferred an increased odds ratio for thrombosis overall (7.8, 95% CI 3.0-20.2, p < 0.001) as well as in men (8.9, 95% CI 3.0-26.1; p < 0.001) and women (37.8, 95% CI 6.5-213.9; p < 0.01). A high plasma homocysteine is a risk factor for thrombosis in patients with a normal coagulation profile. This common abnormality should be sought in patients with otherwise unexplained thrombotic episodes. Key Words: Homocysteine—Thrombosis—Clotting.

Hyperhomocysteinemia and Venous Thrombosis

Deep vein thrombosis (DVT) leads to venous ulcers in later life. Venous ulcers are the majority of chronic lower extremity wounds. Recent evidence suggests that hyperhomocysteinemia is an independent risk factor for venous thrombosis. Other evidence suggests that dietary supplementation with folic acids and vitamins helps to change hyper-homocysteinemia. This may be the key to wound management in the future.

Long-term prognostic significance of homocysteine in middle-aged and elderly

OBJECTIVE

We investigated the association among increased levels of plasma homocysteine (Hcy), all-cause mortality, and cardiovascular events.

METHODS

Hcy was measured in 670 middle-aged and elderly subjects with no previous manifest cardiovascular disease. The follow-up period was 15 years.

RESULTS

Subjects with Hcy ≥ 10.8 μmol/l (n = 231) had a significant higher incidence of all-cause mortality (p < 0.001) and CV events (p < 0.001) compared with subjects with Hcy < 10.8 μmol/l (n = 439). However, there was no association on high levels of Hcy and VTE events or stroke.

CONCLUSION

Increased levels of Hcy are associated with all-cause mortality and CV events.

Risk factors associated with retinal vein occlusion

AIMS

Retinal vein occlusion (RVO) is the most frequent retinal vascular disease after diabetic retinopathy in which arterial risk factors are much more relevant than venous factors. The objective was to evaluate the role of risk factors in the development of the first episode of RVO.

SUBJECTS AND METHODS

One hundred patients with RVO [mean age 56 years, 42% females and mean body mass index (BMI) 27.5 kg/m(2)] were recruited consecutively from the outpatient clinic of a tertiary hospital in Valencia (Spain). All subjects underwent clinical assessment including anthropometric and blood pressure measurements and laboratory test including homocysteine, antiphospholipid antibodies (aPLAs) and thrombophilia studies. In half of the subjects, a carotid ultrasonography was performed. Three control populations matched by age, sex and BMI from different population-based studies were used to compare the levels and prevalence of arterial risk factors. One cohort of young patients with venous thromboembolic disease was used to compare the venous risk factors.

RESULTS

Blood pressure levels and the prevalence of hypertension were significantly higher in the RVO population when compared with those for the general populations. There was also a large proportion of undiagnosed hypertension within the RVO group. Moreover, carotid evaluation revealed that a large proportion of patients with RVO had evidence of subclinical organ damage. In addition, homocysteine levels and prevalence of aPLAs were similar to the results obtained in our cohort of venous thromboembolic disease.

CONCLUSIONS

The results indicate that hypertension is the key factor in the development of RVO, and that RVO can be the first manifestation of an undiagnosed hypertension. Furthermore, the majority of these patients had evidence of atherosclerotic disease. Among the venous factors, a thrombophilia study does not seem to be useful and only the prevalence of hyperhomocysteinaemia and aPLAs is higher than in the general population.

Three different presentation of same pathophysiology

We report three male patients of younger age group presented with acute vein thrombosis of different sites, right lower limb, cortical venous sinuses thrombosis with cerebral vascular accident and third case is mesenteric vein thrombosis. All patients were Vegetarian, had low level of cobalamin with marked hyper homocysteinemia with normal serum and red cell folic acid. The low Cobalamin level was not suspected secondary to pernicious anemia, based on the fact that there was no evidence of atrophic gastritis and an absence of antiparietal cell antibodies. There were no evident of immobilization, recent surgery, malignancy, antiphospholipid antibody, myeloproliferative disorder, and hormone replacement therapy. No deficiencies in protein C, protein S, or antithrombin III, normal factor V Leiden, no prothrombin gene mutation 20210A and no clone for paroxysmal nocturnal hemoglobin-urea were detected, no cause was found for the thrombosis apart from their secondary hyperhomocysteinemia.

Hyperhomocysteinemia and methylenetetrahydrofolate reductase C677T polymorphism in cerebral veno-sinus thrombosis

There is limited data on the role of hyperhomocysteinemia as a risk factor for cerebral veno-sinus thrombosis (CVT) in Indians. We examined the association between plasma homocysteine (Hcy), methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism, and CVT in 185 patients with aseptic CVT (puerperal 80 and nonpuerperal 105) and 248 healthy controls (puerperal 67 and nonpuerperal 181). Fasting Hcy was higher in patients compared to controls (20.25 ± 5.97 vs 9.81 ± 5.19 μmol/L, P < .001) and associated with 4.54-fold (95% confidence interval [CI]: 2.74-7.53) increase in risk of CVT. Risk was higher in puerperal (odds ratio [OR]: 8.7, 95% CI: 2.73-26.91) compared to nonpuerperal CVT (OR: 3.82, 95% CI: 2.09-6.96). Plasma Hcy was higher in MTHFR 677TT compared to 677CT and 677CC genotypes (34.44 ± 32.8 vs 25.81 ± 33.3 vs 18.50 ± 23.7 μmol/L, respectively, P < .001), but the risk associated with MTHFR 677TT was insignificant (OR: 1.91, 95% CI: 0.53-7.06). We conclude that hyperhomocysteinemia is a risk marker for Indian patients with aseptic CVT. MTHFR 677TT genotype is not linked with CVT but is a determinant of plasma Hcy.

Plasma homocysteine levels, methylene tetrahydrofolate reductase polymorphisms, and the risk of thromboembolism in children

INTRODUCTION

Hyperhomocystenemia (HHcy) is a risk factor for thrombosis in adults. Polymorphisms in methylene tetrahydrofolate reductase (MTHFR) enzyme may cause HHcy. Data on their role in pediatric thromboembolism (TE) are sparse.

MATERIALS AND METHODS

Charts of patients from 1989 to 2007, with documented TE, were reviewed. Homocysteine (Hcy) levels were defined both as per the adult normal range and the age-specific normal ranges from literature.

RESULTS

A total of 141 patients (67 females, 74 males) were identified. With age-specific normal ranges for Hcy, 15 patients were found to have HHcy: 6 had CT, 9 patients had CC, and none had TT MTHFR genotype. When adult normal range was used, HHcy (>12 μmol/L) was seen in 7 patients: 4 had CT and 3 had the CC genotype. Again, none had TT genotype. In addition, the mean Hcy levels were unaffected by sex and ethnicities, but universal folic acid supplementation (post 1996) lowered the mean.

CONCLUSIONS

(1) Age-specific ranges for Hcy should be used in pediatrics for accurate diagnosis of HHcy. (2) MTHFR C677T polymorphism is not a risk factor in pediatric TE. (3) Folic acid supplementation could play a role in lowering the prevalence of HHcy.

A cross-sectional study to detect the prevalence of hyperhomocysteinemia in cases of deep vein thrombosis

Hyperhomocysteinemia is a known risk factor for the development of deep vein thrombosis (DVT). Various studies have been conducted in the western countries to know the prevalence of hyperhomocysteinemia in patients with DVT and in general population. There is no documented literature of the prevalence of hyperhomocysteinemia in Indian population. Thus the aim of this study was to determine the prevalence of hyperhomocysteinemia in cases of DVT in our population. To evaluate the prevalence of hyperhomocysteinemia, a prospective cross sectional study done on a total of 70 patients admitted in KLES Dr Prabhakar Kore hospital, Belgaum, India. DVT was confirmed by Doppler examination. Serum homocysteine was measured and the data analysed. Statistical significance was calculated using chi square test. A total of 70 patients were studied of which 53 were males and 17 were females. The prevalence of hyperhomocysteinemia among the cases of DVT was 31.428%.The prevalence among males was 35.85% and among females was 17.64%.There was statistically significant association between hyperhomocysteinemia and presence of ischaemic heart disease with a p value of 0.005 on chi square analysis. The prevalence of hyperhomocysteinemia in cases of deep vein thrombosis in our population was 31.428%. There was a statistically significant association between hyperhomocysteinemia and ischaemic heart disease.

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.

Acquired and congenital risk factors associated with cerebral venous sinus thrombosis

The mechanistic paradigm underlying venous thrombosis at atypical locations stems from the observation that most events occur as a result of pathology of the organ system drained by the involved venous segment. Cerebral venous sinus thrombosis stands apart as an exception to this general rule. Although brain and sinus pathology are well established causes, these combined variables account for approximately one third of cases. The marked female preponderance and strong association with gender specific risk factors including hormonal manipulation, pregnancy and the puerperium are particularly notable. Factor V Leiden and prothrombin G20210A mutations and hyperhomocysteinemia represent important risk factors particularly when combined with acquired variables. The association with oral contraception use and the prothrombin G20210A gene mutation may offer insights into the anatomic predilection for cerebral venous sinus involvement as compared to venous thrombosis of the lower extremities. The intent of this review is to summarize the corporate literature of both acquired and congenital risk factors associated with cerebral venous sinus thrombosis in order to assist clinicians in their search for underlying mechanisms and to risk stratify patients for anticoagulation treatment duration and risk of recurrent thrombosis.

Hyperhomocysteinaemia, low folate concentrations and methylene tetrahydrofolate reductase C677T mutation in acute mesenteric venous thrombosis

OBJECTIVES

Acute mesenteric venous thrombosis (AMVT) was first reported by Fagge and was recognised as a distinct clinical entity by Warreen in 1935. However, its pathogenesis is still unclear. Elevated plasma levels of homocysteine (Hcy) are associated with an increased risk of deep vein thrombosis. This case-control study examines the potential association among hyperhomocysteinaemia (hyper-Hcy), low serum folate and vitamin B(12) levels and the common C677T mutation of the MTHFR gene in patients with AMVT.

MATERIALS AND METHODS

Sixty-three patients with AMVT and 75 sex- and age-matched healthy controls were recruited, and their plasma Hcy, folate and vitamin B(12) levels were measured by high performance liquid chromatography (HPLC) and immunological assays. The polymorphism of MTHFR C677T was detected by PCR-RFLP.

RESULTS

The mean plasma Hcy levels were significantly higher in patients with AVMT compared with controls (23.5 standard deviation (S.D.) 8.8 vs. 12.6+/-6.6micromoll(-1), P<0.01). The fasting Hcy correlated negatively with folate (AMVT: r=-0.42, P<0.01;

CONTROL

r=-0.40, P<0.01). The frequency of homozygous (TT) genotype in MTHFR C677T mutation was significantly higher in patients with AMVT than that in control subjects (33% vs. 17%; chi square (chi(2))=6.31, P<0.05; odds ratio (OR)=2.80; 95% confidence interval (CI): 1.25-6.25). Compared with the control subjects, the mean serum vitamin B(12) levels were lower in patients, but it was not statistically significant (365+/-88pmoll(-1) vs. 408+/-108pmoll(-1), P>0.05).

CONCLUSIONS

Hyper-Hcy and low serum folate levels were associated with an increased risk of AMVT. The homozygous (TT) genotype of MTHFR gene mutation may be a crucial hereditary risk factor in the development of AMVT for a Chinese population.

Genetic variations and their influence on risk and treatment of venous thrombosis

Venous thrombosis (VT) is a highly prevalent disease. Risk factors can be genetic or acquired. The well-established genetic polymorphisms predisposing to thrombophilic disorders can be divided into rare 'loss-of-function mutations' in anticoagulant proteins and common 'gain-of-function mutations' in procoagulant proteins, which are weaker risk factors. In addition to functional polymorphisms, defects in common pathways affecting biosynthesis or clearance of plasma coagulation factors and their relations to VT risk have been detected. Recently, investigations regarding genetic variations and response to drug treatment, relevant for the pathogenesis as well as therapy of venous thromboembolism have been performed. The methodical advances in genetic research have led to the identification of a number of new variants with still unclear association to VT. This review aims to discuss the established genetic risk factors as well as some candidate predictors of VT. Further, the recent developments in pharmacogenomics are reviewed.

Thrombophilia states and markers of coagulation activation in the prediction of pediatric venous thromboembolic outcomes: a comparative analysis with respect to adult evidence

Venous thromboembolism (VTE) in children is an important clinical concern for which risk factors include clinical conditions that incite venous stasis, endothelial damage, or thrombophilia (i.e., hypercoagulability) states. Acquired thrombophilia and markers of coagulation activation are common in pediatric VTE, while potent genetic thrombophilia states are less frequently encountered; nevertheless, the latter are more likely to present in the pediatric age than in older adulthood. Sequelae of VTE and its treatment in childhood survivors include bleeding, persistent or progressive thrombosis, recurrent VTE, and (when venous return from a limb is affected) the development of post-thrombotic syndrome (PTS). The focus of the present review is to discuss the role of tests of thrombophilia and coagulation activation as key predictors of outcome in this disease. Based upon this understanding, coupled with existing knowledge of clinical prognostic factors, new risk-stratified approaches of antithrombotic therapy have emerged for clinical investigation in the field of pediatric VTE.

Thrombophilia and pregnancy complications: cause or association?

Both acquired and inherited thrombophilia is associated with an increased risk of pregnancy failure (i.e. sporadic and recurrent miscarriage, late fetal loss), as well as hypertensive pregnancy complications such as pre-eclampsia and HELLP syndrome. The question of whether this relationship can be considered causal is rather philosophical. For practical purposes, the consistency and strengths of associations, potential mechanisms and, most importantly, the possibility to intervene with anticoagulants are reviewed. Relevant methodological issues in the case of thrombophilia and pregnancy complications consist of differences between observational and experimental research and quality issues in randomized controlled trials. The mechanisms associating thrombophilia and pregnancy complications are likely to involve effects on trophoblast differentiation rather than mere hypercoagulability. Therapeutic options comprise aspirin as well as (low molecular weight) heparin. For women with antiphospholipid antibody syndrome, this treatment is often suggested although the evidence is limited. For women with inherited thrombophilia and unexplained recurrent pregnancy loss, at present there is no evidence supporting treatment. Observational research is hampered by severe methodological flaws or inconsistent results. Two published randomized trials have not used an adequate comparator (i.e. no treatment or placebo). Currently, randomized controlled trials with no treatment or placebo are being carried out and results should be awaited before implementing a potentially harmful intervention in pregnant women with inherited thrombophilia and a history of pregnancy complications.

Hyperhomocysteinemia and thrombosis: an overview

CONTEXT

Homocysteine, a sulfur-containing amino acid, absent in natural diets, is a metabolic intermediary in transmethylation and transsulfuration reactions. Such reactions are essential to normal cellular growth, differentiation, and function. Excess homocysteine is associated with vascular disease and related disorders.

OBJECTIVE

To review homocysteine metabolism, the pathogenesis and classification of hyperhomocysteinemia, and the published literature investigating the association of homocysteine and methylenetetrahydrofolate reductase defects with arterial and venous thromboembolism and related disorders. The role of vitamin supplementation in patients with hyperhomocysteinemia is addressed.

DATA SOURCES

Published medical and scientific literature. Articles addressing the objectives were selected and reviewed. Pertinent studies and conclusions were summarized, grouped, and contrasted.

CONCLUSIONS

The association of hyperhomocysteinemia and arterial and venous thrombosis is controversial. Severe hyperhomocysteinemia is associated with atherosclerosis. The effect of mild hyperhomocysteinemia is less certain. Coinheritance of methylenetetrahydrofolate reductase defects and factor V Leiden is likely to increase the risk of venous thromboembolism. The association of methylenetetrahydrofolate reductase defects combined with no additional thrombophilic risk factors with venous thrombosis is less clear. High doses of folic acid to lower homocysteine levels might not be necessary.

Pregnancy Failure and Heritable Thrombophilia

Heritable thrombophilia is associated with an increased risk for pregnancy failure, defined as sporadic and recurrent miscarriage, late fetal loss, and other vascular pregnancy complications such as preeclampsia and intrauterine growth retardation. The pathogenesis is likely to include effects on trophoblast differentiation and not solely hypercoagulability. This is in line with the observation that most recurrent miscarriages occur early. Therapeutic options include aspirin as well as low-molecular-weight heparin. However, in women with heritable thrombophilia and unexplained recurrent pregnancy loss, evidence is not available as published trials have not used an adequate comparator (no treatment or placebo). Currently, randomized controlled trials with no treatment or placebo are being carried out and results should be awaited before implementing a potentially harmful intervention in pregnant women with heritable thrombophilia and a history of pregnancy failure. Both infertility and pregnancy failure are extremely distressing for couples with the desire to have children. Pregnancy failure comprises (recurrent) early miscarriage, as well as late pregnancy loss. The role of heritable thrombophilia in pregnancy failure is reviewed, with a focus on recurrent miscarriage, in terms of epidemiology, etiology, and potential therapeutic implications.

Changes in haemostasis during normal pregnancy: does homocysteine play a role in maintaining homeostasis?

Homocysteine, derived from the demethylation of the ammo acid methionine, is either further catabolised by trans-sulfuration to cysteine or remethylated to methionine. Remethylation to methionine requires the cofactors, folate and vitamin B12. Folate is an effective homocysteine-lowering agent and, thus, homocysteine and folate status are inversely related. Hyperhomocysteinaemia is a strong independent risk factor for venous thromboembolism (VTE) and is associated with adverse pregnancy outcomes such as pre-eclampsia, placental abruption, early pregnancy loss and neural-tube defects. Pregnancy is a risk factor for VTE as a result of prothrombotic changes in levels of haemostatic factors. However, despite this hypercoagulable state, the incidence of pregnancy-associated VTE is relatively low. Hyperhomocysteinaemia is associated with abnormalities in markers of coagulation activation, and recent research suggests that folic acid supplementation, as well as lowering homocysteine, lowers markers of coagulation activation and increases levels of coagulation inhibitors. Tissue factor (TF) is the initiator of blood coagulationin vivo, and homocysteine induces TF expressionin vitro. During pregnancy, monocyte TF expression is lower than that in the non-pregnant state, and this lowering of TF may act to counterbalance increases in coagulation activation. Furthermore, despite a high folate requirement, several studies have reported that homocysteine is lower in normal pregnancy than in the non-pregnant state. Although the exact mechanism of homocysteine lowering during pregnancy is unclear, one possible outcome of lower homocysteine may be the protection of women from pregnancy complications and VTE, and thus lower homocysteine may contribute to maintaining homeostasis in haemostasis.

Thromboembolic disease after total hip arthroplasty: who is at risk?

The strong activation of the clotting cascade that occurs during total hip arthroplasty places patients at increased risk for venous thromboembolism. The risk is higher in those patients with the following predisposing factors, listed in approximate order of importance: hip fracture; malignancy, particularly if associated with chemotherapy; antiphospholipid syndrome; immobility; history of venous thromboemholism; administration of tamoxifen; raloxifene; oral contraceptives or estrogen; morbid obesity; stroke; atherosclerosis; and an American Society of Anesthesiologists physical status classification of 3 or greater. The following risk factors are weak or controversial: advanced age; diabetes mellitus; congestive heart disease; atrial fibrillation; varicose veins; and smoking. However, 50% of patients who develop thromboembolism after total hip arthroplasty have no clinical predisposing factors. In a matched, controlled study, we defined the major genetic predispositions that increase the risk of venous thromboembolism after total hip arthroplasty: deficiency of antithrombin III (< 75%) and protein C (< 70%), and prothrombin gene mutation. Preoperative genetic screening in conjunction with the recognized clinical risk factors can help categorize postoperative venous thromboembolism risk and differentiate patients who can be protected with milder and safer prophylaxis (eg, aspirin, intermittent pneumatic compression) compared with those at higher risk who need to be anticoagulated.

Plasma homocysteine and hematological factors in patients with venous thromboembolic diseases in Kuwait

BACKGROUND

Venous thromboembolic disease (VTE) is a common cause of morbidity in Kuwait, but the risk factors have not been studied. Hyperhomocysteinemia has been suggested as one of the risk factors. We postulate that hyperhomocysteinemia acts synergistically with hematological variables to increase VTE risk. This study evaluates the roles of hyperhomocysteinemia and hematological variables in patients with VTE.

METHODS

We measured fasting plasma total homocysteine (tHcy), activated protein C resistance, protein C (PC), protein S (PS) and antithrombin (AT) in 201 patients with VTE and 166 healthy controls. We also measured factor VIII, factor II, lupus anticoagulant, anticardiolipin, serum vitamin B12, folate, creatinine, lipid profile, glucose, full blood count and red cell folate. The glomerular filtration rate (GFR) was calculated from creatinine.

RESULTS

When patients on warfarin were excluded, 13.1% of patients (18 out of 137) had a deficiency in PC, 16.8% (23 out of 137) had a deficiency in PS, and when patients on heparin were excluded, 8.3% of patients (14 out of 168) had low AT. Spearman's rank correlation analysis showed that tHcy had significant correlations with age, creatinine and PS, and significant inverse correlations with GFR, high-density lipoprotein cholesterol and serum folate. Partial correlation analysis after correcting for age and sex showed that tHcy retained a significant correlation with creatinine, GFR and serum folate. Binary logistic regression analyses of the determinants of hyperhomocysteinemia included age, creatinine, GFR and serum folate. Multivariate logistic regression analysis showed significant association of tHcy with VTE (OR = 5.6; p < 0.0001) in the presence of known risk factors for VTE.

CONCLUSION

We conclude that elevated tHcy is a significant risk factor for the development of VTE, and therefore, it should be included in the workup for patients at risk of VTE, but the determinants of tHcy should be kept in mind.

Acquired Thrombophilia during Pregnancy

Acquired thrombophilic states are common causes of thrombosis and other forms of pregnancy-associated complications. A growing body of evidence is available to guide the use of anticoagulants in patients who have antiphospholipid antibodies; unfortunately, the results of these studies are conflicting, and solid, evidence-based treatment recommendations cannot be made. Other forms of acquired thrombophilia are uncommon or of unknown clinical significance. Treatments aimed at mitigating the impacts of these states lack clear evidence to support their use.

Deep vein thrombosis in an athletic military cadet

STUDY DESIGN

Resident's case problem.

BACKGROUND

A 21-year-old healthy athletic male military cadet with complaint of worsening diffuse left knee pain was evaluated 4 days after onset. The knee pain began 2 hours after completing a long car trip, worsened over the subsequent 3 days, and became almost unbearable during the return trip. The patient reported constant pain, limited knee motion, and difficulty ambulating. In addition, he was unable to perform physical military training or attend academic classes due to the severe left knee pain. Past medical history revealed a mild left lateral calf strain 21/2 weeks prior, which completely resolved within 24 hours of onset.

DIAGNOSIS

Our physical examination led us to either monoarticular arthritis, pseudothrombophlebitis (ruptured Baker's cyst), or a lower leg deep vein thrombosis (DVT) as the cause of knee pain. Diagnostic imaging of this patient revealed a left superficial femoral vein thrombosis and popliteal DVT, with bilateral pulmonary emboli (PE).

DISCUSSION

A systematic differential diagnosis was undertaken to rule out a potentially fatal DVT diagnosis as the cause of knee pain, despite minimal DVT risk factors. The physical therapist in a direct-access setting must ensure timely evaluation and referral of a suspected DVT, even when patient demographics cause the practitioner to question the likelihood of this diagnosis. The physical examination findings, clinical suspicion, and established clinical prediction rules can accurately dictate the appropriate referral action necessary.

Heterozygous methylenetetrahydrofolate reductase 677C-T gene mutation with mild hyperhomocysteinemia associated with intrauterine iliofemoral artery thrombosis

Neonatal thrombosis is a serious event that can cause mortality or severe morbidity. Newborn-related factors, including genetic prothrombotic risk factors, may affect the occurrence of neonatal thrombosis. In this report, a case of intrauterine iliofemoral arterial thrombosis associated with mild hyperhomocysteinemia caused by methylenetetrahydrofolate reductase 677C-T gene mutation is presented. We suggest that methylenetetrahydrofolate reductase gene mutation might be investigated in neonates and their families presenting with thromboembolic disease.

Hereditary thrombophilia in ethnic Omani patients

Hereditary thrombophilias are a group of inherited conditions that predispose to thrombosis. Mutations like factor V Leiden, prothrombin gene variant 20210A, and hereditary hyperhomocysteinemia are associated with an increased risk for thromboembolism as compared to mutations in natural inhibitors of coagulation. There is also evidence that multiple defects co-exists in persons with a tendency for thrombosis. We studied prothrombotic determinants, namely protein C, protein S, and AT along with factor V Leiden (1691G-->A), prothrombin gene mutation (20210G-->A), CBS 844ins68 mutation, and MTHFR mutation (677C-->T) in consecutive ethnic Omani patients with first episode of a thrombophilic event, namely, deep vein thrombosis (DVT), and/or pulmonary embolism (PE) or thrombosis at an unusual site. Fasting plasma homocysteine was also analyzed. Factor V Leiden and the prothrombin gene mutation were not seen in any patient nor in any control subject studied. The thermolabile MTHFR mutation (677C-->T) was present in 14 patients (35.89%) whereas the CBS 844ins68 mutation was documented in 6 patients (15.38%); 3 patients were common in both groups. Six patients had low protein C (15.38%), two patients had low protein S (5.12%), but none had low AT levels. Interestingly, one patient had triple abnormality, namely, PC deficiency with both CBS 844ins68 mutation as well as the MTHFR mutation (677C-->T) whereas another two patients had the latter two mutations together. This data set, although small, reflects the importance of multiple screening strategies. The yield appears high, emphasizing the referral pattern to a tertiary health center. Of these patients, 43.58% had either or both the hyperhomocysteinemic mutations studied, whereas in 38.46% of these patients, no underlying cause for thrombophilia could be documented.

The John Charnley Award: heritable thrombophilia and development of thromboembolic disease after total hip arthroplasty

We retrospectively assessed whether heritable thrombophilia-hypofibrinolysis was more common in patients developing venous thromboembolism after total hip replacement than among control patients who did not develop venous thromboembolism, as an approach to better identify causes of venous thromboembolism after total hip arthroplasty. Twenty patients with proximal deep venous thrombosis after THA and 23 patients with symptomatic pulmonary embolism were compared with 43 control patients who did not have postoperative venous thromboembolism. Five of 42 patients with venous thromboembolism (12%) and 0 of 43 control patients (0%) had antithrombin III deficiency (< 75%). Nine of 42 patients with venous thromboembolism (21%) and 2 of 43 control patients (4.7%) had protein C deficiency (< 70%). Ten of 43 patients with venous thromboembolism (9 heterozygous, 1 homozygous; 23%) and 1 of 43 control patients (heterozygous; 2%) had the prothrombin gene mutation. Patients who had venous thromboembolism after total hip arthroplasty were more likely than matched control patients to have heritable thrombophilia with antithrombin III or protein C deficiency, or homo-heterozygosity for the prothrombin gene mutation. Screening for these three tests of heritable thrombophilia before total hip arthroplasty should improve the identification of patients with a reduced risk of venous thromboembolism who may need only mild thromboprophylaxis, and of those patients with heritable thrombophilia in whom prophylaxis should be more aggressive.

LEVEL OF EVIDENCE

Prognostic study, Level II-1 (lesser-quality RCT). See the Guidelines for Authors for a complete description of levels of evidence.

Legg-perthes disease and heritable thrombophilia

The etiology of Perthes' disease is unclear. Recent reports have suggested that inheritable thrombophilic disorders may be one of its pathogenetic causes. The G20210A prothrombin gene, factor V Leiden, and MTHFR C677T mutations have been identified as predisposing genetic factors for thrombosis. Ninety children diagnosed with Perthes' disease were studied. A family history of thrombosis and any other personal thromboembolic events were researched. PCR and endonuclease digestion were used to analyze factor V Leiden, prothrombin G20210A, and MTHFR C677T. Two hundred healthy donors were included as a control group. No patient had a family or personal history of early thrombotic events. Four children with Perthes' disease (4.4%) were heterozygous for G20210A polymorphism compared with controls (odds ratio: 2.07; 95% confidence interval: 0.40-8.46). No association between factor V Leiden and Perthes' disease was observed. Three patients (3.33%) were heterozygous for factor V Leiden (odds ratio: 1.36; 95% confidence interval: 0.32-5.84). The prevalence of different genotypes of C677T MTHFR did not show statistical differences compared with controls. Eleven patients were homozygous for this polymorphism (odds ratio: 1.02; 95% confidence interval: 0.42-2.44). This study does not support the screening of this group of polymorphism in patients with Perthes' disease.

Hyperhomocysteinaemia as a Risk Factor for Deep-vein Thrombosis

OBJECTIVE

Several studies have shown a relation between hyperhomocysteinaemia and vascular disease. To assess the risk of deep-vein thrombosis (DVT) associated with hyperhomocysteinaemia, we studied plasma homocysteine levels in patients with deep-vein thrombosis and in normal control subjects.

MATERIALS AND METHODS

We measured plasma homocysteine levels in 48 patients with deep-vein thrombosis and in 33 healthy controls matched to the patients according to age and sex. Plasma homocysteine levels were measured with high performance liquid chromatography and fluorescence detection. Hyperhomocysteinaemia was defined as a plasma homocysteine level about 15 micromol/L in both groups. The diagnosis of all patients with deep-vein thrombosis (n=48) was verified by Doppler ultrasonography.

RESULTS

Plasma homocysteine levels were found to be increased in the deep-vein thrombosis group compared the control group (p<0.001, t-test). The mean plasma homocysteine level in the patients was 17.1 SD 5.13 micromol/L (range 6.4-31.3), and that in the controls was 9.0 SD 1.27 micromol/L (range 6.0-11.5). The association between elevated homocysteine levels and venous thrombosis was stronger among men than among women.

CONCLUSIONS

The increased plasma homocysteine levels we have observed may have a causative role in the development of deep-vein thrombosis.

Detection of 677CT/1298AC "double variant" chromosomes: implications for interpretation of MTHFR genotyping results

PURPOSE

Genotyping 37,026 individuals as part of a thrombophilia evaluation, we determined and analyzed the genotypic frequencies of the 677CT and 1298AC mutations in the methylenetetrahydrofolate reductase (MTHFR) gene.

METHODS

The 677CT and 1298AC mutations in the MTHFR gene were determined by either a laboratory-developed test involving PCR amplification and restriction digestion utilizing the ABI 3100 capillary electrophoresis apparatus (Applied Biosystems Inc) or by using an Analyte Specific Reagent (ASR) supplied by Third Wave Technologies. The genotype for three specimens with triple variant MTHFR mutations were confirmed by DNA sequencing on the ABI 3100 capillary electrophoresis apparatus.

RESULTS

The MTHFR frequencies of the 677CT/1298AA, 677CC/1298AC, 677CT/1298AC, 677CC/1298AA, 677TT/1298AA, 677CC/1298CC, 677TT/1298AC, and 677CT/1298CC genotypes were 0.228, 0.208, 0.198, 0.153, 0.122, 0.088, 0.0005, and 0.0003, respectively.

CONCLUSIONS

Individuals containing double variant MTHFR mutations on one allele (cis) cannot be distinguished between compound heterozygotes (trans) for 677CT and 1298AC mutations in routine clinical testing, a genotype associated with thrombophilia. Such patients could be inappropriately counseled for being at high risk for thrombotic episodes. Until information regarding prevalence and the clinical consequences of this double variant (cis) allele becomes available, caution should be used in interpreting the genotyping results of compound heterozygosity for 677CT and 1298AC.

[Effect of hyperhomocysteinemia and methylenetetrahydrofolate reductase 677C --> T mutation in venous thromboembolism risk of young adults]

BACKGROUND AND OBJECTIVE

To investigate whether hyperhomocysteinemia and methylenetetrahydrofolate reductase (MTHFR) 677C --> T mutation are associated with venous thromboembolism in young Spanish adults.

PATIENTS AND METHOD

One hundred adult patients younger than 50 years and 177 controls with similar age and gender.

RESULTS

Hyperhomocysteinemia was present in 21% of the patients and 3.3% of the controls (p < 0.001), and MTHFR 677C --> T mutation was found in 25 and 14.7%, respectively (p = 0.03). Odds ratio (OR) for thromboembolism in hyperhomocysteinemic patients was 7.5 (95% CI, 2.9-19.2; p < 0.001), and in patients with MTHFR 677C --> T mutation the OR was 1.9 (95% CI, 1.1-3.5; p = 0.03). In a subgroup of 76 patients without other thrombogenic factors, thromboembolism persisted associated with hyperhomocysteinemia, yet an association with MTHFR 677C --> T mutation was not confirmed.

CONCLUSIONS

Hyperhomocysteinemia, but not MTHFR 677C --> T mutation, is a risk factor for venous thromboembolism in young adults without other thrombogenic factors.

Risk factors for venous thrombosis in Swedish children and adolescents

AIM

To identify prothrombotic risk profiles in children and adolescents referred to a regional coagulation centre in southern Sweden for a first thrombotic event.

METHODS

One hundred and twenty-eight consecutive children and adolescents (newborn to 20 y) referred for evaluations of a first episode of venous thrombosis were investigated. Clinical data were collected retrospectively, and the following variables were investigated: protein C, protein S, antithrombin; resistance to activated protein C; the genotypes FV-G1691A, F II-G20210A, MTHFR-C677T, MTHFR- A1298C; coagulation factors VIII and XI.

RESULTS

104/128 subjects (81%) had identifiable acquired risk factors, most often indwelling catheters and hormone therapy. Predisposing genetic factors related to thromboembolic events were revealed in 53/83 (64%) of subjects who agreed to follow-up blood sampling, and 17/83 (20%) had two or more inherited risk factors. Combinations of genetic and acquired risk factors were identified in 45/83 (54%) of the subjects, and 77/83 (93%) had at least one such risk factor. Both sexes had one peak in frequency at less than 1 y of age and then an increase during adolescence, more in females than in males. Plasma values for coagulation factors VIII and XI were age appropriate and showed a normal Gaussian distribution.

CONCLUSION

This study identified prothrombotic risk profiles in almost all children and adolescents with venous thrombosis, which underlines the importance of careful evaluation of genetic and acquired risk factors.

Gene-gene and gene-environment interactions in mild hyperhomocysteinemia

Mild/moderate hyperhomocysteinemia (HHcy), a highly prevalent condition, is independently associated with an increased risk of arterial and venous thromboembolic diseases. Early reports of the association of mild/moderate HHcy with juvenile venous thromboembolism have shown familiarity for HHcy in relatives of index cases with thrombosis. Similar to inherited thrombophilia defects, inheritance of the HHcy phenotype was accordingly retained important for the definition of HHcy as an independent risk factor for thrombosis. A number of common polymorphisms in genes coding for methylenetetrahydrofolate reductase(MTHFR), methionine-synthase, methionine-synthase reductase and cysthationine beta-synthase (CBS) have been explored for their association with homocysteine levels, fasting and post-methionine load, and with thrombotic diseases. MTHFR thermolability accounts for a 10-fold increase in the risk of mild/moderate HHcy. With the possible exception of the CBS844ins68 insertion, there is no evidence for an increased risk of HHcy for any of these polymorphisms, isolated or in association with MTHFR thermolability. Environmental factors and MTHFR thermolability are main determinants of the HHcy phenotype.If mild/moderate HHcy is a pathogenetic risk factor for thrombosis, intervention aimed to improve the vitamin status appears of major importance, irrespective of common gene polymorphisms of the homocysteine metabolism.

Homocysteine, MTHFR and risk of venous thrombosis: a meta-analysis of published epidemiological studies

CONTEXT

It has been suggested that elevated total plasma homocysteine levels are associated with the risk of venous thrombosis.

OBJECTIVE

To assess the relationship of homocysteine and the MTHFR 677TT genotype and the risk of venous thrombosis by conducting a meta-analysis of all relevant studies.

DATA SOURCES AND SELECTION

Studies (case-control or nested case-control) were identified by searches of electronic literature for relevant reports published before July 2003 on homocysteine and the MTHFR 677TT genotype and venous thrombosis as an end-point, by hand-searching reference lists of original articles (including meta-analyses) on this topic and by contact with investigators in the field.

DATA EXTRACTION

A meta-analysis of 24 retrospective (n = 3289 cases) and three prospective studies (n = 476 cases) was carried out to examine the association of homocysteine with venous thrombosis. A meta-analysis of 53 studies (n = 8364 cases) of the MTHFR 677TT genotype (that increases homocysteine) was carried out to assess if this association is causal.

DATA SYNTHESIS

A 5 micromol L(-1) higher measured homocysteine level was associated with a 27% (95% CI: 1-59) higher risk of venous thrombosis in prospective studies and a 60% (95% CI: 10-134) higher risk in retrospective studies. The 677TT genotype was associated with a 20% (95% CI: 8-32) higher risk of venous thrombosis compared with the 677CC genotype. In contrast with non-American studies, the 677TT genotype had no effect on venous thrombosis in North America, due probably to the higher intake of folate and riboflavin in North America.

CONCLUSION

This meta-analysis of prospective and retrospective studies demonstrates a modest association of homocysteine with venous thrombosis. The elevated risk associated with the MTHFR 677TT genotype provides some support for causality.

Hyperhomocysteinaemia in chronic liver diseases: role of disease stage, vitamin status and methylenetetrahydrofolate reductase genetics

BACKGROUND/AIMS

The liver plays a key role in sulphur aminoacid metabolism hence, homocysteine metabolism may be impaired in chronic liver diseases. The aim of this study was to investigate, in patients affected by chronic liver diseases, (1) the prevalence of hyperhomocysteinaemia and (2) the role of its determinants such as the stage and the aetiology of disease, vitamin status, genetic documented alterations (methylenetetrahydrofolate reductase deficiency) and presence/absence of documented malignant evolution (hepatocellular carcinoma).

MATERIAL AND METHODS

One hundred and thirty patients with chronic liver disease (34 with chronic active hepatitis, 12 with fatty liver and 88 with liver cirrhosis) and 50 healthy age-matched control subjects were included into the study.

RESULTS

Hyperhomocysteinaemia was defined as homocysteine plasma levels greater than 12.6 micromol/l. Hyperhomocysteinaemia prevalence in liver cirrhosis group was 40.9%, significantly higher (all P<0.01) with respect to controls (12%), chronic active hepatitis (14.7%) and fatty liver (25%) groups and increased with Child-Pugh stage [Child A: 22.2%, Child B (50%); Child C (58.3%)]. In chronic-active hepatitis and liver cirrhosis, the prevalence of subjects with methylenetetrahydrofolate reductase C677-->T mutation (both as CT and as TT) and hyperhomocysteinaemia results in significantly higher levels with respect to controls. Methylenetetrahydrofolate reductase C677-->T mutation and disease stage showed to be the most important predictive factors of hyperhomocysteinaemia in liver cirrhosis whereas the influence of homocysteine-related vitamin status seems to have a secondary role.

CONCLUSIONS

In conclusion hyperhomocysteinaemia is highly prevalent in liver cirrhosis but not in other chronic liver diseases; it may contribute to fibrogenesis and vascular complication of liver cirrhosis.

Hyperhomocysteinemia, low folate and vitamin B12 concentrations, and methylene tetrahydrofolate reductase mutation in cerebral venous thrombosis

BACKGROUND AND PURPOSE

Elevated plasma levels of homocysteine are associated with an increased risk of deep-vein thrombosis. Through a case-control study, we examined the potential association among homocysteine, folate and vitamin B12 levels, and the common C677-->T mutation in the methylene tetrahydrofolate reductase (MTHFR) gene in patients with cerebral venous thrombosis (CVT).

METHODS

Forty-five patients with CVT and 90 control subjects were studied. Plasma levels of homocysteine (fasting and after methionine load), folate, and vitamin B12 were measured. Genotyping of the MTHFR gene was also performed. The estimated risk of CVT associated with hyperhomocysteinemia, low vitamin levels, and MTHFR mutation were expressed as odds ratio (OR) and its 95% CI (crude and after adjusting by other independent variables).

RESULTS

The adjusted OR for CVT associated with high (>90th percentile) fasting levels of homocysteine was 4.6 (1.6 to 12.8). The association between low plasma folate values (<10th percentile) and presence of CVT was 3.5 (1.2 to 10.0) after adjustment for confounding factors. There was a higher frequency of MTHFR mutation in patients with CVT (22% versus 10%), but it was not statistically significant (P=0.098). Patients with MTHFR mutation and low folate levels presented the highest homocysteine levels.

CONCLUSIONS

High plasma concentrations of homocysteine and low plasma folate levels were associated with an increased risk of CVT in this population in which low socioeconomic conditions and deficient nutritional status may contribute to its relatively high incidence.

Hyperhomocysteinemia and other thrombophilic risk factors in 26 patients with cerebral venous thrombosis

Despite the continuous description of new conditions pre-disposing for cerebral venous thrombosis (CVT), no apparent cause is found in about 30% of cases. Hyperhomocysteinemia (hyper-Hcy) is an established risk factor for deep venous thrombosis and stroke but has not been clearly associated with increased risk of CVT. We assessed the prevalence of hyper-Hcy and other thrombophilic risk factors in a population of 26 consecutive patients with non-pyogenic CVT, by review of a prospectively maintained database. The prevalences of hyper-Hcy and prothrombin G20210A, factor V G1691A and methylenetetrahydrofolate reductase (MTHFR) C677T mutations in these patients were compared with those in 100 healthy controls and 100 patients with cerebroarterial disease. The prevalence of hyper-Hcy was greater in patients with CVT (10/26, 38.5%) than healthy controls (13/100; OR 4.18, 95% CI 1.58-11.16) and comparable with that in patients with cerebroarterial disease (42/100). No significant differences were found in the prevalences of prothrombin or MTHFR mutation. No factor V mutation was found. Our findings indicate that hyper-Hcy is associated with an increased risk of CVT. Additional prospective cohort studies on large series of patients are required to clarify the time relationship between hyper-Hcy and the thrombotic event.

Heterozygous methylene tetrahydrofolate reductase mutation with mild hyperhomocysteinemia associated with deep vein thrombosis

Hyperhomocysteinemia is known to be associated with arterial occlusive vascular disease and venous thrombosis. Here, we report a young ethnic Omani patient with recurrent venous thrombosis who was found to be heterozygous for 677C-T mutation in the methyltetrahydrofolate reductase (MTHFR) enzyme. Moderate hyperhomocystenemia was also observed, in the presence of normal red cell folate and serum B12 levels. No other documented marker of hereditary thrombophilia could be demonstrated in this patient, in spite of extensive investigation on multiple occasions.

Effects of some pre-analytical conditions on the measurement of homocysteine and cysteine in plasma

The association of hyperhomocysteinemia and hypercysteinemia with the risk of arterial and venous thrombosis is well documented. While it is known that standardized pre-analytical conditions are necessary for reliable measurement of plasma total homocysteine, the effects of pre-analytical conditions on cysteine measurement are less well known. The aim of this study was to evaluate the effects of pre-analytical conditions on the measurement of homocysteine and cysteine. We observed that the concentration of total homocysteine in plasma increased significantly with time (38% after 6 h), whereas total cysteine decreased (5% after 2h) when blood anticoagulated with ethylenediaminetetraacetic tripotassium salt was kept at room temperature. These changes were minimized when acidic citrate dextrose was used as an anticoagulant and were abolished when blood samples were immediately placed on crushed ice, independently of the anticoagulant. Storage of plasma for 72h at room temperature induced a small (≅6%), but significant, decrease in cysteine when blood was collected in ethylenediaminetetraacetic tripotassium salt. In contrast, homocysteine was stable in plasma for 72h, independently of the anticoagulant used. In conclusion, if blood samples for plasma total homocysteine and cysteine measurement cannot be kept on ice, they should be collected in acidic citrate dextrose to minimize the artifactual changes.

Genetically Determined Procoagulant States and Heparin Use

The propensity for both arterial and venous thrombotic disorders involves a genetic predetermination that operates In concert with environmental factors or triggers. Appropriate clinical assessment and therapeutic recommendations for patients with thrombosis requires a thorough knowledge of genetic variables that influence this propensity. This review focuses on the pathophysiology, natural history, and molecular biology of defined thrombophilic risk factors relevant to the care of patients with thrombotic disorders.

[A common mutation C677T in the 5,10-methyltetrahydrofolate reductase gene is associated to idiopathic deep venous thrombosis]

PURPOSE

Moderate hyperhomocysteinemia is a risk factor for deep venous thrombosis. The homozygous C677T methylenetetrahydrofolate reductase (MTHFR) mutation is associated with increased level of total plasma homocysteine. The association between homozygous C677T mutation and deep venous thrombosis is still controversial.

METHOD

In order to evaluate this association, we studied the prevalence of C677T mutation in 168 patients with confirmed deep venous thrombosis; 31 with an idiopathic deep venous thrombosis (group A) and 137 with thromboembolic event explained by one or more clinical and/or biological risk factors (group B).

RESULTS

The distribution of genotypes was different between group A and B [++/+ -/- -(n(%))] : 9(29)/10(32)/12(39) vs 16(12)/57(42)/64(46) (chi(2) : 6.03; P: 0.049). The comparison between homozygotes and the two other genotypes showed significant statistical relationship between homozygous genotype and idiopathic character of deep venous thrombosis (chi(2) : 6.01; P : 0.014; OR : 3.09 [IC 95% : 1.06-8.53]).

CONCLUSION

These results suggest that homozygous C677T methylenetetrahydrofolate reductase mutation could be considered as a genetic risk factor for venous thrombosis.

[Hyperhomocysteinemia: an independent risk factor or a simple marker of vascular disease? 2. Epidemiological data]

Elevated plasma total homocysteine (tHcy) is considered as a risk factor for occlusive cardiovascular disease (CVD). This concept is based on the observations of premature vascular disease in patients with homocystinuria and on the association between tHcy and increased risk of CVD in prospective studies. However, some observations have raised questions about tHcy as a risk factor. First, low risk population based prospective studies tend to indicate a weak association or no association between tHcy and CVD. Second, several traditional risk factors for CVD are associated with tHcy and may confound the relation between tHcy and CVD. Third, the C667T transition of the methylenetetrahydrofolate reductase causes a moderate increase in tHcy but no or only minor increased CVD risk. Thus, only placebo-controlled intervention studies with tHcy-lowering B-vitamins and clinical endpoints can provide additional valid arguments for the debate over whether tHcy is a causal CVD risk factor.

Serum homocysteine, thermolabile variant of methylene tetrahydrofolate reductase (MTHFR), and venous thromboembolism: Longitudinal Investigation of Thromboembolism Etiology (LITE)

We sought to examine prospectively the association of serum homocysteine and the methylene tetrahydrofolate reductase (MTHFR) C677T gene polymorphism with risk of venous thromboembolism (VTE). We studied these relationships in a nested case-control study of 303 VTE cases and 635 matched controls from a population-based cohort of 21,680 adults from six U.S. communities. The highest quintile of serum homocysteine carried a non-statistically significant adjusted odds ratio of 1.55 (95% CI, 0.93-2.58) compared to the lowest quintile in the overall cohort but a significant association among adults aged 45-64 years (OR = 2.05, 95% CI, 1.10-3.83) and an inverse association in those > or = 65 years of age. Carriers of the MTHFR C677T polymorphism were not at higher risk for VTE than those with normal genotype (OR = 0.74, 95% CI = 0.56-0.98). Our prospective data showed, at most, a weak relationship between homocysteine and VTE risk, with associations larger among younger participants. MTHFR C677T was not a risk factor for VTE.

Familial hyperhomocysteinemia: multiple venous thrombosis in four generations of a family

We describe a family in which four generations (eight members) had deep vein thrombosis of the lower limb and three of the alive members had documented hyperhomocysteinemia. In addition, one of the family members had evidence of arterial thrombosis in the form of cerebral infarcts. Interestingly, all affected members in the family were males.

[Cerebral-vein thrombosis: retrospective study of twenty seven cases]

PURPOSE

Among the locations of venous thrombosis, even if rare, cerebral-vein thrombosis is a severe event with a high mortality rate. No aetiology is found in 20 to 30% of the cases. In recent years, inherited coagulation disorders have been described, as risk factors for venous thrombosis. We report the results of a retrospective study of 27 patients who suffered cerebral-vein thrombosis, in which coagulation abnormalities have been searched for.

METHOD

The patients were referred to the haemostasis laboratory of the Henri Mondor hospital between august 1982 and June 1988, after a cerebral-vein thrombosis. The predisposing factors, personal and family history of thromboembolism, clinical presentation, thrombosis location, evolution under treatment and long-term outcome, have been noted. Deficiencies in antithrombine, protein C, protein S, the Factor V Leiden and the G20210A prothrombin-gene mutation, the presence of lupus anticoagulant, of anticardiolipin antibodies as well as a hyperhomocysteinaemia have been searched, either at the initial presentation, or a posteriori.

RESULTS

Fourty-one percent of patients had a coagulation abnormality. The prevalence of the different abnormalities was: inherited deficiency in AT 7.4%, in PC 8%, in PS 12.5%, factor V Leiden mutation 12%, G20210A prothrombin-gene mutation 12%. Two patients had combined defects: AT and PC deficiency in one, F V Leiden and F II G20210A mutations in one. e of the patient had lupus anticoagulant. Three patients had a significant rate of anticardiolipin antibodies. Five patients out of eight displayed a moderate hyperhomocysteinaemia. Nothing (past history, age, predisposing factors) distinguished those patients bearing a coagulation disorder from the others. The venous thromboembolic relapse rate of 15 % (4/27 patients). Three of them had an inherited thrombophilic abnormality.

CONCLUSION

We recommend an investigation of the haemostasis after every cerebral venous thrombosis.