Homocysteine, methylenetetrahydrofolate reductase C677T polymorphism and the B-vitamins: a facet of nature-nurture interplay.

BACKGROUND: Methylenetetrahydrofolate reductase 677 (MTHFR 677) polymorphism may provoke hyperhomocysteinemia when folate status is low. The influence of MTHFR 677 mutation on homocysteine (HCY) levels in relation to vitamin B12 and folate status was investigated in the current study. SUBJECTS AND METHODS: 113 vegetarians, 123 omnivorous Germans, and 117 omnivorous Syrians were recruited. MTHFR 677 genotype, HCY, methylmalonic acid (MMA), total serum vitamin B12, serum folate, and vitamin B6 were determined using conventional methods. RESULTS: Omnivorous Germans displayed the lowest HCY levels compared with vegetarians and Syrians (median 8.0, 10.4, and 11.3 micromol/l, respectively). The highest serum folate and the highest MMA levels were found in vegetarians (median folate = 30.0; MMA = 355 nmol/l). Among vegetarians and Syrians, TT subjects had higher HCY levels than other genotypes which were, however, no longer significant in the highest folate tertiles. When the data were pooled, the odds ratio (OR, 95% CI) for HCY > 12 micromol/l was 3.81 (1.55-9.34) in TT compared with CC subjects. The OR increased to 28.85 (4.63-179.62) in TT subjects who had folate in the lowest tertile, and to 21.84 (4.81-99.1) in TT subjects who had MMA in the highest MMA tertile. CONCLUSION: MTHFR 677 TT individuals are more liable to hyperhomocysteinemia under vitamin B12 deficiency than the other two genotypes. In such a case, relative folate shortage may progressively increase HCY levels. TT individuals may have increased folate and vitamin B12 requirements compared to the other CC and CT genotypes.     

The risk of venous thromboembolism associated with the factor V Leiden mutation and low B-vitamin status.

Venous thromboembolism (VTE) is a multi-factorial disease involving numerous genetic and environmental risk factors. In this study we investigated the occurrence and the risk associated with factor V Leiden, hyperhomocysteinemia and low folate and vitamin B12 levels in young patients with thrombosis. We studied 78 patients (33 females/45 males, mean age 33 years) with a history of thrombosis in a lower limb. Additionally, 98 healthy subjects (45 females/54 males, mean age 44 years) were included. Serum levels of homocysteine (Hcy), folate and vitamin B12 were assayed. Factor V Leiden and methylenetetrahydrofolate reductase (MTHFR) C677T mutations were investigated in all subjects. Factor V Leiden was highly prevalent in the patients (39% heterozygous, 10% homozygous vs. 6.3% heterozygous in controls). An increase in the risk of idiopathic VTE was associated with Hcy levels > 15.2 micromol/l (odds ratio, OR = 2.83), folate < 15.1 nmol/l (OR = 7.49) and vitamin B12 < 182 pmol/l (OR = 11.97). Low levels of folate or vitamin B12 were independently and strongly associated with the risk of VTE in a multivariate model (OR for idiopathic thrombosis = 16.44 and 10.76, respectively). Twenty patients (53%), carriers of factor V Leiden, had low levels of vitamin B12, compared to 28% of patients who were non-carriers of the mutation (p = 0.03). In contrast, none of the control carriers of the mutation had a low level of vitamin B12. The risk of VTE associated with lower levels of vitamin B12 and folate was stronger than that introduced by elevated Hcy levels. The increased risk of VTE, accompanied by factor V Leiden, may be related to confounding environmental factors.     

Endothelial nitric oxide synthase -786T>C, but not 894G>T and 4a4b, polymorphism influences plasma homocysteine concentrations in persons with normal vitamin status

BACKGROUND: Nitric oxide (NO) plays a relevant role in various events during atherogenesis. In vitro data suggest that NO may modulate homocysteine (Hcy) concentrations. The aim of this study was to investigate the role of endothelial nitric oxide synthase (eNOS) -786T>C, 894G>T, and 4a4b polymorphisms in influencing Hcy concentrations. METHODS: Blood samples were obtained from 1287 unrelated persons. Plasma Hcy was measured by fluorescence polarization immunoassay, folate and vitamin B(12) by RIA, vitamin B(6) by HPLC, and eNOS and methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms by PCR with restriction fragment length polymorphism analysis. RESULTS: MTHFR 677C>T polymorphism significantly influenced Hcy concentrations after adjustment for all confounding variables (P <0.0001 for trend). Univariate analysis showed that the eNOS -786T>C polymorphism, but not 894G>T and 4a4b, was significantly associated with the risk of having Hcy in the third tertile [>13.4 micromol/L; odds ratio (OR) = 1.2; 95% confidence interval (CI), 1.02-1.5; P = 0.03]. After adjustment for all variables known to influence Hcy, the -786T>C polymorphism still influenced Hcy concentrations (OR = 1.9; 95% CI, 1.1-3.2; P = 0.01). By analyzing the influence of eNOS polymorphisms on plasma Hcy concentrations according to vitamin concentrations (folate, vitamin B(6), and vitamin B(12)), age, and smoking habits, we found a significant association between the eNOS -786T>C polymorphism and Hcy in nonsmokers, in persons with normal vitamin status, and in persons <60 years. CONCLUSION: The eNOS -786T>C polymorphism, but not 894G>T and 4a4b, influences plasma Hcy concentrations mildly but significantly and independently.     

Screening for serum total homocysteine in newborn children

BACKGROUND: Newborn screening for total homocysteine (tHcy) in blood may identify babies with vitamin B12 (B12) deficiency or homocystinuria, but data on the causes of increased tHcy in screening samples are sparse. METHODS: Serum concentrations of tHcy, cystathionine, methionine, folate, and B12 and the methylenetetrahydrofolate reductase (MTHFR) 677C > T polymorphism were determined in 4992 capillary blood samples collected as part of the routine screening program in newborn children. Methylmalonic acid (MMA), gender (SRY genotyping), and the frequency of six cystathionine beta-synthase (CBS) mutations were determined in 20-27% of the samples, including all samples with tHcy > 15 micromol/L (n = 127), B12 < 100 pmol/L (n = 159), or methionine > 40 micromol/L (n = 154). RESULTS: The median (5th-95th percentile) tHcy concentration was 6.8 (4.2-12.8) micromol/L. B12 status, as determined by serum concentrations of B12, tHcy, and MMA, was moderately better in boys than in girls. tHcy concentrations between 10 and 20 micromol/L were often associated with low B12, whereas tHcy > 20 micromol/L (n = 43) was nearly always explained by increased methionine. tHcy did not differ according to folate concentrations or MTHFR 677C > T genotypes. None of the babies had definite CBS deficiencies, but heterozygosity led to low cystathionine, increased methionine, but normal tHcy concentrations. CONCLUSION: Increased tHcy is a common but not specific finding in newborns. The metabolite and vitamin profiles will point to the cause of hyperhomocysteinemia. Screening for tHcy and related factors should be further evaluated in regions with high prevalence of homocystinuria and in babies at high risk of B12 deficiency.     

Hyperhomocysteinemia is associated with deep venous thrombosis of the lower extremities in Tunisian patients

OBJECTIVES: To test the association between hyperhomocysteinemia (HHC) and deep venous thrombosis (DVT) of lower extremities in Tunisians. DESIGN AND METHODS: This case-control study included 90 patients with DVT of the lower extremities and 160 healthy controls. Plasma homocysteine, vitamin B(12) and folate were determined using immunoenzymatic methods. Logistic regression models were performed to test whether the association between HHC and DVT is independent and to precise determinants of HHC in DVT patients. RESULTS: Plasma total homocysteine concentrations were significantly higher in patients with DVT (17.4+/-11.5 micromol/L) and in patients with idiopathic DVT (15.2+/-6.4 micromol/L) as compared to controls (11.5+/-3.3 micromol/L). HHC was significantly associated (p<0.001) with all DVT (OR, 8.82; 95% CI, 3.96-19.6) as well as idiopathic DVT (OR, 7.40; 95% CI, 3.01-10.8). These associations persisted after adjustment for several thrombosis risk factors. In patients with DVT, HHC was related to folate and vitamin B(12) concentrations, but neither to the type of occurrence nor to the recurrence of DVT. CONCLUSION: HHC is independently associated with first DVT of lower extremities in Tunisians. Homocysteine should be assessed in patients with DVT and the effect of vitamin B supplementation should be tested among them.     

Predictors of vitamin B6 and folate concentrations in older persons: the InCHIANTI study

BACKGROUND: Low dietary intake and low serum concentrations of vitamin B6 and/or folate are associated with increased risk of vascular events, possibly because of their association with inflammation, which plays a crucial role in the pathogenesis of cardiovascular diseases. METHODS: Using data from 1320 participants in the population-based InCHIANTI study (586 men and 734 women; median age, 69 years; range, 21-102 years) for whom complete data on folate, vitamin B6, inflammatory markers, 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T sequence variant, and important covariates were available, we evaluated the association of inflammatory markers with circulating concentrations of vitamin B6 and folate, independently of dietary vitamin intake, circulating vitamin concentrations, and MTHFR C677T sequence variant. RESULTS: According to multiple linear regression analysis, C-reactive protein and interleukin-6 receptor were strongly and negatively associated with circulating vitamin B6 but not with folate concentrations, independent of age, sex, serum creatinine, serum albumin, total energy intake, smoking history, dietary nutrient intake, and circulating homocysteine and vitamin concentrations. Serum folate concentrations were related to MTHFR 677 TT genotype in persons with folate intake in the lowest tertile (< 221.2 microg/day). Vitamin C and retinol intakes were strongly and positively associated with serum folate concentrations independent of age, sex, serum creatinine, serum albumin, total energy intake, smoking history, homocysteine plasma concentrations, dietary nutrient intakes, serum vitamin B6 and vitamin B12 concentrations, and MTHFR C677T sequence variant. CONCLUSIONS: Low serum vitamin B6, but not serum folate, concentrations are independent correlates of the proinflammatory state, and both are influenced by antioxidant reserves.     

Association of homocysteine level with biopsy-proven non-alcoholic fatty liver disease: a meta-analysis

Previous studies have reported inconsistent findings regarding the association between plasmatic higher of homocysteine level and non-alcoholic fatty liver disease. We aimed to investigate this association by conducting a meta-analysis. Literature was searched on PubMed from inception to January 2015. Eight studies evaluating plasma level of homocysteine in biopsy-proven non-alcoholic fatty liver disease subjects compared to healthy controls were included. Compared with the controls, non-alcoholic fatty liver disease patients witnessed a higher level of homocysteine [standard mean difference (SMD): 0.66 µmol/L, 95% CI: 0.41, 0.92 µmol/L], and were associated with a significant increased risk for hyperhomocysteinemia [odds ratio (OR) 5.09, 95% CI: 1.69, 15.32]. In addition, patients with non-alcoholic fatty liver presented 0.45 µmol/L higher levels of homocysteine compared to healthy controls (95% CI: 0.09, 0.82 µmol/L), whereas non-alcoholic steatohepatitis patients had 1.02 µmol/L higher levels of homocysteine (95% CI: 0.28, 1.76 µmol/L). There was neither difference of folate level nor vitamin B12 level between non-alcoholic fatty liver disease subjects and healthy controls. This study revealed that non-alcoholic fatty liver disease patients presented an increased serum concentration of homocysteine, and were associated with an increased risk of hyperhomocysteinemia. Further studies are needed to demonstrate a causal role of hyperhomocysteinemia in non-alcoholic fatty liver disease.     

Association between antipsychotic drugs, antidepressant drugs and venous thromboembolism: results from the EDITH case-control study

Cohort studies suggest that exposure to antipsychotic agents may be associated with an increased risk of venous thromboembolism (VTE). Few data concerning antidepressant drugs are available. Using a different methodological approach, the aim of this study was to estimate the association between neuroleptic and antidepressant drug use and the risk of VTE. We report the results of a case-control study designed to evaluate interactions between acquired and inherited risk factors of VTE. We included 677 cases hospitalized with deep vein thrombosis and or pulmonary embolism with no major acquired risk factor for VTE, and 677 controls matched for gender and age. Drug exposure was defined as current use of drugs at admission. Neuroleptic exposure was associated with an increased risk of VTE (OR = 2.1, 95% CI 1.4-3.2). Among neuroleptics, antipsychotic agent use was associated with a 3.5-fold increased risk of VTE (OR = 3.5, 95% CI 2.0-6.2). No association was found between antidepressant drug exposure and the risk of VTE (OR = 1.1, 95% CI 0.9-1.5). In this hospital-based case-control study, exposure to antipsychotic drugs was associated with an increased risk of VTE. These results, added to previous results, suggest that clinicians should consider antipsychotic drug exposure as a potential risk factor of VTE. More studies are needed in order to further elucidate this adverse effect, and to determine the possible predisposing factors and the biological mechanisms involved.     

Impact of environmental and hereditary risk factors on the clinical manifestation of thrombophilia in homozygous carriers of factor V:G1691A

Summary.  Background : Limited data exist on the clinical manifestations of homozygous factor (F)V:G1691A mutation (FV Leiden) and the impact of environmental and genetic risk factors. Objectives : To assess the contribution of these factors on the thrombophilic phenotype. Patients and methods : In a retrospective multicenter cohort study 165 individuals with homozygous FV:G1691A mutation, of whom 129 had previous venous thromboembolism (VTE), were included. To study the role of environmental risk factors, patients were compared by the use of a standardized questionnaire to 165 sex- and age-matched individuals (reference group A); of these, two had previous VTE. To assess the role of genetic risk factors, factor (F)II:G20210A and MTHFR:C677T were determined in individuals homozygous for FV:G1691A and in 177 healthy individuals without previous VTE (reference group B). Results : The first VTE occurred significantly earlier in women (median age 25 years) than men (35.5 years). In 81% of women and 29% of men an environmental risk factor was present before first VTE. Oral contraceptives increased the risk of thrombosis 4-fold [odds ratio (OR) 4.0, 95% confidence interval (CI) 1.7, 10.4] in women with homozygous FV:G1691A. Postoperative and post-traumatic VTE as first manifestation occurred in 13% and 15% of surgical/traumatic events in patients and in 0.7% and 1.8% in reference group A, respectively (OR 19.7, 95% CI 2.5, 154 and OR 9.2, 95% CI 1.1, 79.4). Heterozygous FII:G20210A was more prevalent in symptomatic patients (11.7%) compared with reference group B (2.8%, OR 4.6, 95% CI 1.6, 13.2). The prevalence of homozygous MTHFR:C677T genotype was similar in patients and reference group B. Conclusions : Our study supports the concept of thrombophilia as a multifactorial disorder. The knowledge of coexisting factors predisposing to VTE is useful for medical advice for primary and secondary prophylaxis in these patients.     

Factor V Leiden, pregnancy complications and adverse outcomes: the Hordaland Homocysteine Study

BACKGROUND: The factor V Leiden (FVL) mutation is the most common cause of inherited thrombophilia in Caucasian populations, and women with this variant allele are at increased risk for pregnancy complications. AIM: To examine whether the FVL allele is associated with pregnancy complications and adverse outcomes in a population-based study, and to identify potential factors that interact with the FVL genotype. DESIGN: Retrospective cohort study in a geographically-defined area. METHODS: Polymorphisms of factor V 1691G-->A, methylenetetrahydrofolate reductase (MTHFR) 677C --> T and 1298A --> C and plasma levels of total homocysteine, folate and vitamin B(12) were determined in blood samples collected in 1992-1993 from 5874 women aged 40-42 years, and linked with 14 474 pregnancies in the same women, recorded in the Medical Birth Registry of Norway, 1967-1996. RESULTS: The allelic frequency of FVL was 3.7% (6.9% heterozygotes, 0.3% homozygotes). Maternal FVL mutation was associated with significantly higher risks of pre-eclampsia (OR 1.63, 95%CI 1.15-2.30), pre-eclampsia at <37 weeks (OR 2.76, 1.34-5.70), low birth weight (OR 1.34, 95%CI 1.03-1.74) and stillbirth (OR 2.20, 95%CI 1.45-3.36). The presence of a variant allele for the 677C --> T MTHFR polymorphism strengthened the association between FVL and stillbirth (OR 3.34, 95%CI 1.95-5.73) (p(interaction) = 0.034). DISCUSSION: FVL mutation is a significant risk factor for pregnancy complications and adverse outcomes, and MTHFR 677CT/TT genotype can further enhance the risk of stillbirth.     

Association between serum vitamin D levels and venous thromboembolism (VTE): A systematic review and meta-analysis of observational studies

ObjectiveAlthough many studies have attempted to unravel the relationship between vitamin D deficiency and the incidence of VTE, the results remained inconsistent. To address this discrepancy, we performed a systematic review and meta-analysis to precisely disentangle the relationship between serum vitamin D levels and VTE risk.MethodsThe Web of Science, Scopus, PubMed/Medline, Embase, and Google Scholar databases were searched for all available observational studies that reported the risk of venous thromboembolism (VTE) based on serum vitamin D levels categories. The search was performed up to March 2020.ResultsSeven studies were included. The overall analysis showed a significantly increased risk of VTE in subjects with low levels of serum vitamin D compared with those with normal vitamin D levels (RR = 1.34; 95% CI: 1.07–1.69; P = 0.011). In a sensitivity analysis, we did not observe a significant effect of any individual study on the combined effect sizes. Nevertheless, significant heterogeneity was present among the studies (Cochrane Q test, p = 0.018, I² = 61%). In the stratified analysis, low vitamin D levels were positively associated with an increased risk of VTE in prospective population-based studies (RR = 1.31; 95% CI: 1.06–1.61; P = 0.010) and in subjects below 60 years old (RR = 1.28; 95% CI: 1.07–1.54; P = 0.060).Conclusionour systematic review and meta-analysis showed that a low serum vitamin D level was indeed associated with an increased risk of VTE.     

High concentrations of soluble P-selectin are associated with risk of venous thromboembolism and the P-selectin Thr715 variant

BACKGROUND: The cell adhesion molecule P-selectin has an important role in the pathophysiology of thrombosis. The effect on venous thromboembolism (VTE) of increased circulating concentrations of soluble P-selectin (sP-selectin) and their association with the P-selectin variant Thr715Pro is still uncertain. METHODS: This study was a case-control study of 116 patients with confirmed recurrent VTE and at least 1 event of unprovoked deep venous thrombosis or pulmonary embolism, and 129 age- and sex-matched healthy individuals. We measured sP-selectin by ELISA and P-selectin gene (SELP) variation by genotyping and sampled blood after a mean interval of 2.55 years after the most recent VTE event. RESULTS: The mean (SD) sP-selectin concentration was higher in patients than in controls: 47.3 (15.0) microg/L vs 36.8 (11.0) microg/L, P <0.001. The unadjusted odds ratio (OR) for sP-selectin >55.1 microg/L, representing the 95th percentile for controls, was 8.5 (95% CI, 3.7-23.3; P <0.001) and increased after adjustment for factor V Leiden, the prothrombin G20210A variant, increased factor VIII, and hyperhomocysteinemia (OR, 10.6; 95% CI, 4.1-31.2; P <0.001). Pro715 carriers were more prevalent among controls than patients (21.7% vs 14.7%). sP-selectin concentrations were lower in this subgroup than in noncarriers: 31.3 (7.9) microg/L vs 44.1 (14.1) microg/L; P <0.001). CONCLUSIONS: Increased sP-selectin concentrations are associated with VTE and genotype status. sP-selectin concentrations are lower in individuals carrying the P-selectin Pro715 variant than in those without this variant.     

Obesity and risk of venous thromboembolism among postmenopausal women: differential impact of hormone therapy by route of estrogen administration. The ESTHER Study

BACKGROUND: Oral estrogen use and elevated body mass index (BMI) increase the risk of venous thromboembolism (VTE). Recent data suggest that transdermal estrogen might be safe with respect to thrombotic risk. However, the impact of transdermal estrogen on the association between overweight (25 kg m(-2) < BMI < or = 30 kg m(-2)) or obesity (BMI >30 kg m(-2)) and VTE risk has not been investigated. METHODS: We carried a multicenter case-control study of VTE among postmenopausal women aged 45-70 years, between 1999 and 2005, in France. Case population consisted of women with a first documented idiopathic VTE. We recruited 191 hospital cases matched with 416 hospital controls and 62 outpatient cases matched with 181 community controls. RESULTS: The odds ratio (OR) for VTE was 2.5 [95% confidence interval (CI):1.7-3.7] for overweight and 3.9 (95% CI: 2.2-6.9) for obesity. Oral, not transdermal, estrogen was associated with an increased VTE risk (OR = 4.5; 95% CI: 2.6-7.7 and OR = 1.1; 95% CI: 0.7-1.7, respectively). Compared with non-users with normal weight, the combination of oral estrogen use and overweight or obesity further enhanced VTE risk (OR = 10.2; 95% CI: 3.5-30.2 and OR = 20.6; 95% CI: 4.8-88.1, respectively). However, transdermal users with increased BMI had similar risk as non-users with increased BMI (OR = 2.9; 95% CI: 1.5-5.8 and OR = 2.7; 95% CI: 1.7-4.5 respectively for overweight; OR = 5.4; 95% CI: 2.1-14.1 and OR = 4.0; 95% CI: 2.1-7.8 respectively for obesity). CONCLUSIONS: In contrast to oral estrogen, transdermal estrogen does not confer an additional risk of idiopathic VTE in women with increased BMI. The safety of transdermal estrogen on thrombotic risk has to be confirmed.     

Statins but not fibrates are associated with a reduced risk of venous thromboembolism: a hospital-based case-control study

Previous studies of selected patients have suggested a reduction in the risk of venous thromboembolism with the use of statins. The objective of this study is to evaluate the influence of statin use on the risk of venous thromboembolic (VTE) events. The study is a case-control study (EDITH: Etude des Déterminants et Interactions de la Thrombose Veineuse), designed to investigate the genetic and environmental risk factors of VTE. A total of 377 patients consecutively hospitalized in the Brest University Hospital for a documented VTE event, between May 2000 and May 2002, and 377 age- and sex-matched controls were studied. Statin use was associated with a 58% decreased risk of VTE [odds ratio (OR) 0.42; 95% confidence interval (CI) 0.23-0.76; P = 0.002]. Adjustment for age, gender, coronary heart disease, atherosclerothrombotic disease or current use of aspirin did not alter the result. Neither fibrates (OR 1.38; 95% CI 0.76-2.52; P = 0.26), nor thienopyridines (OR 1.07; 95% CI 0.48-2.41; P = 0.85) were associated with a reduced risk of VTE. Aspirin use tended to decrease the risk of VTE, but this result was not significant (OR, 0.66; 95% CI, 0.42-1.05). The use of statins is associated with a significant reduction in the risk of VTE, irrespective of age, gender, and past history of atherosclerothrombotic disease, as well as the use of aspirin. This possible protective effect of statins warrants further investigations.     

Thrombophilic risk factors in patients with severe carotid atherosclerosis.

Carotid stenosis and atrial fibrillation are the strongest risk factors for ischemic stroke. Ongoing prevention efforts include the identification of novel factors that increase the risk for carotid atherosclerosis. The aim of this study was to determine the thrombophilic risk profile of patients with severe carotid stenosis by evaluating a number of genetic and metabolic risk factors [factor (F)II G20210A, factor V Leiden, MTHFR C677T polymorphisms, anticardiolipin antibodies (aCL), lipoprotein(a) (Lp(a)), and homocysteine (Hcy)]. The study population consisted of 615 patients [(410 M/205 F; median age 73 (26-94) years] with severe (> 70%) carotid stenosis, and 615 apparently healthy subjects [(410 M/205 F; age 73 (31-92) years]. On multivariate analysis, independent risk factors were elevated Hcy [odds ratio (OR) 7.6, 95% confidence interval (CI) 4.8, 11.8] and Lp(a) levels (OR 2.9, 95% CI 2.1, 3.9), the presence of aCL (OR 5.7, 95% CI 3.1, 10.4) and heterozygosity for FII G20210A polymorphism (OR 2.8, 95% CI 1.3, 5.9). In the subgroup of women, independent risk factors for severe carotid atherosclerosis were: high levels of Hcy and Lp(a) and the presence of aCL, whereas hyperhomocysteinemia, elevated Lp(a) levels, aCL, FII G20210A and MTHFR 677TT polymorphisms remained independent risk factors in the subgroup of men. The results of the present study demonstrate that the prevalence of the thrombophilic risk factors is increased in patients with severe carotid atherosclerosis.     

The effectiveness of anticoagulant and antiplatelet agents in preventing venous thromboembolism during stroke rehabilitation: a historical cohort study

OBJECTIVE: To determine the effectiveness of anticoagulant and antiplatelet agents in preventing venous thromboembolism (VTE) during stroke rehabilitation. DESIGN: Historical cohort study. SETTING: Acute inpatient rehabilitation hospital. PARTICIPANTS: Consecutive patients (N=1506) with ischemic and hemorrhagic stroke admitted for rehabilitation. INTERVENTIONS: Documented use of anticoagulants (warfarin or anticoagulant doses of heparin), heparin in prophylactic doses, and antiplatelet agents. MAIN OUTCOME MEASURE: Occurrence of deep vein thrombosis detected by ultrasound or venography or pulmonary embolism detected by ventilation perfusion scan, spiral computed tomography, or pulmonary angiography. RESULTS: Fifty-eight VTE events occurred (3.9% incidence or 1.36 events per 1000 patient days), with higher risk in patients with severe stroke. Only therapeutic anticoagulation had a statistically significant protective effect for VTE risk in univariate analysis (odds ratio [OR]=.44; 95% confidence interval [CI],.20-.98). After adjusting for multiple medication use and other factors, including age, stroke onset to admission interval, length of rehabilitation stay, cause of stroke, and admission National Institutes of Health Stroke Scale score, therapeutic anticoagulation gave strong protection against VTE (OR=.37; 95% CI,.15-.88), followed by heparin (OR=.48; 95% CI,.23-.98) but not by antiplatelet agents (OR=.79; 95% CI,.40-1.57). No medications were associated with significant bleeding complications. CONCLUSIONS: Use of therapeutic anticoagulants or prophylactic heparin prevented VTE in stroke patients during inpatient rehabilitation.     

Is the common 677C-->T mutation in the methylenetetrahydrofolate reductase gene a risk factor for neural tube defects? A meta-analysis

The common 677C-->T mutation (+) in the 5,10-methylenetetrahydrofolate reductase gene, resulting in decreased activity of the enzyme, has been associated with spina bifida neural tube defects (NTD). We combined all known Dutch control groups, a total of 1273 individuals, and found a prevalence of the 677C-->T mutation of 8.4%. When compared with the frequencies in 55 SB patients and to mothers with a child with SB their parents, this gave an OR of 1.9 [95% CI 1.1-3.3] for mothers and an OR of 1.5 [95% CI 0.74-3.1] for patients. The frequency of this mutation and its associated risk for NTD may be population-dependent. However, the frequencies of the 677C-->T mutation in different national and international control groups are almost all in the same range. We therefore combined the observed frequencies of the 677C-->T mutation in all reported studies. The mutation was present in 9.2% of controls, resulting in ORs for all reported NTD patients and their parents of: 1.7 [95% CI: 1.1-2.6]; 1.8 [95% CI: 1.1-3.1] and 1.9 [95% CI: 1.3-2.8] for mothers (combined prevalence 14.5%), fathers (combined prevalence 15.5%) and NTD patients (combined prevalence 16.4%), respectively, vs. all international controls. This meta-analysis confirms that the 677C-- >T mutation is a genetic risk factor for NTD.      

The methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and cancer risk: the Croatian case-control study

OBJECTIVES: Methylation abnormalities appear to be important for the pathogenesis of many cancer types. Since methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the methylation process catalyzing reduction of 5,10-methylenetetrahydrofolate to 5-methyl-tetrahydrofolate, C677T polymorphism, which decreases enzyme activity, may be associated with cancer susceptibility. The aim of this work was to investigate the distribution of MTHFR C677T polymorphism between various types of cancer and cancer-free controls and to assess if there is a difference in frequency. MATERIALS AND METHODS: 269 Cancer cases (95 prostate cancer, PC; 81 head and neck, HN; and 93 breast cancers, BC) and 102 healthy controls, free of cancer, were genotyped for C677T MTHFR polymorphism using the PCR-RFLP method. RESULTS: There was no overall difference in C677T genotype distribution between total cancer cohort and controls (p=0.064). However, a significant difference and protective OR was found for the C/T genotype (OR=0.574, 95% CI=0.352-0.935). In a comparison of different cancer types and respective controls, genotype frequencies were significantly different between head and neck carcinoma and controls (p=0.004), again with protective role of C/T genotype (OR=0.356, 95% CI=0.189-0.671). Moderate overrepresentation of C/T was found in respective male controls when compared with prostate cancer patients (p value was 0.074 for C/T vs. C/C comparison). The OR for heterozygous C/T genotype in prostate cancer group was 0.404, pointing to its putative protective role. Genotype and allelic frequencies did not differ significantly between 93 breast cancer patients and their 65 age-matched female controls. CONCLUSION: Our data indicate that the C677T MTHFR polymorphism does not significantly contribute to the inherited genetic susceptibility to breast and prostate cancer, while we show some evidence for possible genetic contribution of this polymorphism to the development of head and neck carcinoma.     

Parenteral vitamin B12 therapy of hyperhomocysteinemia in end-stage renal disease

BACKGROUND: End-stage renal disease (ESRD) is associated with moderately severe hyperhomocysteinemia that is incompletely normalized by oral folic acid therapy and vitamin B12. METHOD: We administered 1 mg hydroxocobalamin parenterally at 14-day intervals to vitamin B12-replete hemodialysis patients who were already consuming 6 mg folic acid daily by mouth. Plasma total homocysteine (tHcy), serum folate, vitamin B12 and methylmalonate were measured immediately before and after 4 and 8 weeks of therapy. RESULTS: Serum folate concentrations were consistently over 25 times the upper normal limit. Hydroxocobalamin therapy increased serum vitamin B12 concentrations 14-fold (p < 0.001) and reduced plasma tHcy by 23% from 29.7 +/- 2.9 to 22.8 +/- 2.5 micromol/L (p < 0.01); serum methylmalonate decreased by one-third (p < 0.05). CONCLUSIONS: These results demonstrate the Hcy-lowering potential of parenteral vitamin B12 in folic acid supplemented vitamin B12-replete hemodialysis patients, and indicate the need for formal dose-optimization studies of this simple, inexpensive and promising approach to Hcy reduction in end-stage renal disease.     

Parenteral vitamin B12 reduces hyperhomocysteinemia in end-stage renal disease

OBJECTIVE: The authors found considerably lower plasma total homocysteine (tHcy) concentrations in patients with end-stage renal disease (ESRD) on maintenance hemodialysis, who routinely received high-dose parenteral vitamin B12, than in comparable patients receiving much higher doses of folic acid but only replacement-dose oral vitamin B12. They therefore sought prospective evidence that high-dose parenterally administered vitamin B12 may partially ameliorate renal failure-associated hyperhomocysteinemia. DESIGN: Open phase 2 clinical trial. SETTING: Outpatient hemodialysis unit. PATIENTS: Fourteen clinically stable patients on maintenance hemodialysis with normal baseline serum vitamin B12 concentrations. INTERVENTION: Three parenteral injections of 1 mg vitamin B12 given at 4-week intervals. Outcome measures: Plasma tHcy and serum vitamin B12 concentrations were measured before, during and 7 months after the termination of vitamin B12 therapy. RESULTS: The mean (and standard error) baseline plasma tHcy was 26.5 (1.8) micromol/L. The plasma tHcy value fell successively after each vitamin injection to reach a value of 23.6 (1.6) micromol/L 1 month after the final injection (p < 0.05), while the serum vitamin B12 concentration increased from 471 (42) pmol/L to 890 (74) pmol/L (p < 0.05). Seven months after the final injection, the serum B12 concentration had fallen and tHcy had risen to near their original values. CONCLUSIONS: Three monthly vitamin B12 injections modestly but distinctly reduced tHcy concentrations in hemodialysis patients whose prior vitamin B12 status was normal. Randomized placebo-controlled clinical trials of longer duration and using larger or more frequent parenteral doses are indicated to determine whether administration of this safe and inexpensive vitamin can improve hyperhomocysteinemia in ESRD.