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Nigwekar SU, Kang A, Zoungas S, Cass A, Gallagher MP, Kulshrestha S, Navaneethan SD, Perkovic V, Strippoli GFM, Jardine MJ. Interventions for lowering plasma homocysteine levels in dialysis patients. Cochrane Database Syst Rev 2016; 2016:CD004683. [PMID: 27243372 PMCID: PMC8520736 DOI: 10.1002/14651858.cd004683.pub4] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
BACKGROUND People with end-stage kidney disease (ESKD) have high rates of cardiovascular events. Randomised controlled trials (RCTs) of homocysteine-lowering therapies have not shown reductions in cardiovascular event rates in the general population. However, people with kidney disease have higher levels of homocysteine and may have different mechanisms of cardiovascular disease. We performed a systematic review of the effect of homocysteine-lowering therapies in people with ESKD. OBJECTIVES To evaluate the benefits and harms of established homocysteine lowering therapy (folic acid, vitamin B6, vitamin B12) on all-cause mortality and cardiovascular event rates in patients with ESKD. SEARCH METHODS We searched Cochrane Kidney and Transplant's Specialised Register to 25 January 2016 through contact with the Information Specialist using search terms relevant to this review. SELECTION CRITERIA Studies conducted in people with ESKD that reported at least 100 patient-years of follow-up and assessed the effect of therapies that are known to have homocysteine-lowering properties were included. DATA COLLECTION AND ANALYSIS Two authors independently extracted data using a standardised form. The primary outcome was cardiovascular mortality. Secondary outcomes included all-cause mortality, incident cardiovascular disease (fatal and nonfatal myocardial infarction and coronary revascularisation), cerebrovascular disease (stroke and cerebrovascular revascularisation), peripheral vascular disease (lower limb amputation), venous thromboembolic disease (deep vein thrombosis and pulmonary embolism), thrombosis of dialysis access, and adverse events. The effects of homocysteine-lowering therapies on outcomes were assessed with meta-analyses using random-effects models. Prespecified subgroup and sensitivity analyses were conducted. MAIN RESULTS We included six studies that reported data on 2452 participants with ESKD. Interventions investigated were folic acid with or without other vitamins (vitamin B6, vitamin B12). Participants' mean age was 48 to 65 years, and proportions of male participants ranged from 50% to 98%.Homocysteine-lowering therapy probably leads to little or no effect on cardiovascular mortality (4 studies, 1186 participants: RR 0.93, 95% CI 0.70 to 1.22). There was no evidence of heterogeneity among the included studies (I² = 0%). Homocysteine-lowering therapy had little or no effect on all-cause mortality or any other of this review's secondary outcomes. All prespecified subgroup and sensitivity analyses demonstrated little or no difference. Reported adverse events were mild and there was no increase in the incidence of adverse events from homocysteine-lowering therapies (3 studies, 1248 participants: RR 1.12, 95% CI 0.51 to 2.47; I(2) = 0%). Overall, studies were assessed as being at low risk of bias and there was no evidence of publication bias. AUTHORS' CONCLUSIONS Homocysteine-lowering therapies were not found to reduce mortality (cardiovascular and all-cause) or cardiovascular events among people with ESKD.
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Affiliation(s)
- Sagar U Nigwekar
- Harvard Medical SchoolDivision of Nephrology, Massachusetts General Hospital, Scholars in Clinical Sciences ProgramBostonMAUSA
| | - Amy Kang
- The University of SydneySydney Medical SchoolSydneyNSWAustralia
- The George Institute for Global Health, The University of SydneyRenal and Metabolic DivisionCamperdownNSWAustralia
| | - Sophia Zoungas
- Monash UniversityDiabetes and Vascular Research Program, Monash Centre for Health Research and Implementation, School of Public Health and Preventive MedicineClaytonVICAustralia
| | - Alan Cass
- The George Institute for Global Health, The University of SydneyRenal and Metabolic DivisionCamperdownNSWAustralia
- Menzies School of Health ResearchPO Box 41096CasuarinaNTAustralia0811
| | - Martin P Gallagher
- The George Institute for Global Health, The University of SydneyRenal and Metabolic DivisionCamperdownNSWAustralia
| | - Satyarth Kulshrestha
- University of Iowa Carver College of MedicineDepartment of Nephrology200 Hawkins Drive‐T307GHIowa CityIAUSA52242
| | | | - Vlado Perkovic
- The George Institute for Global Health, The University of SydneyRenal and Metabolic DivisionCamperdownNSWAustralia
| | - Giovanni FM Strippoli
- The Children's Hospital at WestmeadCochrane Kidney and Transplant, Centre for Kidney ResearchWestmeadNSWAustralia2145
- University of BariDepartment of Emergency and Organ TransplantationBariItaly
- DiaverumMedical Scientific OfficeLundSweden
- Diaverum AcademyBariItaly
- The University of SydneySydney School of Public HealthSydneyAustralia
| | - Meg J Jardine
- The George Institute for Global Health, The University of SydneyRenal and Metabolic DivisionCamperdownNSWAustralia
- Concord Repatriation General HospitalDepartment of Renal MedicineHospital RoadConcordNSWAustralia2139
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Kim H, Park J, Chae H, Lee GD, Lee SY, Lee JM, Oh YS, Kim M, Kim Y. Potential Risk Factors Associated With Vascular Diseases in Patients Receiving Treatment for Hypertension. Ann Lab Med 2016; 36:215-22. [PMID: 26915609 PMCID: PMC4773261 DOI: 10.3343/alm.2016.36.3.215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2015] [Revised: 02/02/2016] [Accepted: 02/11/2016] [Indexed: 11/19/2022] Open
Abstract
Background Currently, the hypertension (HTN) patients undergo appropriate medical treatment, and traditional risk factors are highly controlled. Therefore, potential risk factors of atherosclerotic vascular diseases (AVD) and venous thromboembolisms (VTE) in HTN should be reconsidered. We investigated thrombophilic genetic mutations and existing biomarkers for AVD or VTE in HTN patients receiving treatment. Methods A total of 183 patients were enrolled: AVD with HTN (group A, n=45), VTE with HTN (group B, n=62), and HTN patients without any vascular diseases (group C, n=76). The lipid profile, homocysteine (Hcy) levels, D-dimers, fibrinogen, antithrombin, lupus anticoagulant, and anti-cardiolipin antibody (aCL) were evaluated. Prothrombin G20210A, Factor V G1691A, and methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C were analyzed. Results All patients revealed wild type prothrombin G20210A and Factor V G1691A polymorphisms. The frequency of MTHFR polymorphisms was 677CT (n=84, 45.9%); 677TT (n=46, 25.1%); 1298AC (n=46, 25.1%); and 1298CC (n=2, 1.1%). The MTHFR 677TT genotype tended to increase the odds ratio (OR) to AVD events in HTN patients (OR 2.648, confidence interval 0.982-7.143, P=0.05). The group A demonstrated significantly higher Hcy levels (P=0.009), fibrinogen (P=0.004), and platelet counts (P=0.04) than group C. Group B had significantly higher levels of D-dimers (P=0.0001), platelet count (P=0.0002), and aCL (P=0.02) frequency than group C. Conclusions The MTHFR 677TT genotype and Hcy level could be potential risk factors associated with development of AVD in HTN patients receiving treatment. D-dimer and aCL might be useful to estimate the occurrence of VTE in them.
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Affiliation(s)
- Hyunjung Kim
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Joonhong Park
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Catholic Genetic Laboratory Center, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Hyojin Chae
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Catholic Genetic Laboratory Center, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Gun Dong Lee
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Catholic Genetic Laboratory Center, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Sang Yoon Lee
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Catholic Genetic Laboratory Center, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Jong Min Lee
- Division of Cardiology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Yong Seog Oh
- Division of Cardiology, Department of Internal Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea
| | - Myungshin Kim
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Catholic Genetic Laboratory Center, College of Medicine, The Catholic University of Korea, Seoul, Korea.
| | - Yonggoo Kim
- Department of Laboratory Medicine, College of Medicine, The Catholic University of Korea, Seoul, Korea.,Catholic Genetic Laboratory Center, College of Medicine, The Catholic University of Korea, Seoul, Korea.
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Gao XH, Zhang GY, Wang Y, Zhang HY. Correlations of MTHFR 677C>T polymorphism with cardiovascular disease in patients with end-stage renal disease: a meta-analysis. PLoS One 2014; 9:e102323. [PMID: 25050994 PMCID: PMC4106822 DOI: 10.1371/journal.pone.0102323] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Accepted: 06/17/2014] [Indexed: 01/11/2023] Open
Abstract
OBJECTIVE This meta-analysis was conducted to evaluate the correlations of a common polymorphism (677C>T) in the methylenetetrahydrofolate reductase (MTHFR) gene with risk of cardiovascular disease (CVD) in patients with end-stage renal disease (ESRD). METHOD The following electronic databases were searched without language restrictions: Web of Science (1945∼2013), the Cochrane Library Database (Issue 12, 2013), MEDLINE (1966∼2013), EMBASE (1980∼2013), CINAHL (1982∼2013) and the Chinese Biomedical Database (CBM) (1982∼2013). Meta-analysis was performed using STATA statistical software. Odds ratios (ORs) with their 95% confidence intervals (95%CIs) were calculated. RESULTS Eight cohort studies met all inclusion criteria and were included in this meta-analysis. A total of 2,292 ESRD patients with CVD were involved in this meta-analysis. Our meta-analysis results revealed that the MTHFR 677C>T polymorphism might increase the risk of CVD in ESRD patients (TT vs. CC: OR = 2.75, 95%CI = 1.35∼5.59, P = 0.005; CT+TT vs. CC: OR = 1.39, 95%CI = 1.09∼1.78, P = 0.008; TT vs. CC+CT: OR = 2.52, 95%CI = 1.25∼5.09, P = 0.010; respectively). Further subgroup analysis by ethnicity suggested that the MTHFR 677C>T polymorphism was associated with an elevated risk for CVD in ESRD patients among Asians (TT vs. CC: OR = 3.38, 95%CI = 1.11∼10.28, P = 0.032; CT+TT vs. CC: OR = 1.44, 95%CI = 1.05∼1.97, P = 0.022; TT vs. CC+CT: OR = 3.15, 95%CI = 1.02∼9.72, P = 0.046; respectively), but not among Africans or Caucasians (all P>0.05). CONCLUSION Our findings indicate that the MTHFR 677C>T polymorphism may be associated with an elevated risk for CVD in ESRD patients, especially among Asians.
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Affiliation(s)
- Xian-Hui Gao
- Laboratory of Preventive Medicine, School of Public Health, Liaoning Medical University, Jinzhou, China
- * E-mail:
| | - Guo-Yi Zhang
- Laboratory of Preventive Medicine, School of Public Health, Liaoning Medical University, Jinzhou, China
| | - Ying Wang
- Department of Toxicology, School of Public Health, Liaoning Medical University, Jinzhou, China
| | - Hui-Ying Zhang
- Sleep Monitoring Center, First Affiliated Hospital of Liaoning Medical University, Jinzhou, China
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Role of homocysteine in end-stage renal disease. Clin Biochem 2012; 45:1286-94. [PMID: 22683753 DOI: 10.1016/j.clinbiochem.2012.05.031] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2011] [Revised: 04/26/2012] [Accepted: 05/28/2012] [Indexed: 11/22/2022]
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Houcher B, Houcher Z, Touabti A, Begag S, Torun D, Eğin Y, Akar N, Kadour F. Association of Methylenetetrahydrofolate Reductase C677T and Cystathionine β-Synthase Polymorphisms in Cardiovascular Disease in the Algerian Population. Genet Test Mol Biomarkers 2010; 14:775-80. [DOI: 10.1089/gtmb.2010.0059] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Affiliation(s)
- Bakhouche Houcher
- Department of Biology, Faculty of Sciences, University of Sétif, Sétif, Algeria
| | - Zahira Houcher
- Department of Biology, Faculty of Sciences, University of Sétif, Sétif, Algeria
| | - Abderrezak Touabti
- Department of Medicine, Faculty of Medical Sciences, University of Sétif, Sétif, Algeria
| | - Samia Begag
- Department of Biology, Faculty of Sciences, University of Sétif, Sétif, Algeria
| | - Didem Torun
- Department of Pediatric Genetics, Medical School, Ankara University, Ankara, Turkey
| | - Yonca Eğin
- Department of Pediatric Genetics, Medical School, Ankara University, Ankara, Turkey
| | - Nejat Akar
- Department of Pediatric Genetics, Medical School, Ankara University, Ankara, Turkey
| | - Fatima Kadour
- Department of Medicine, Faculty of Medical Sciences, University of Sétif, Sétif, Algeria
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Kiseljaković E, Resić H, Kapur L, Hasić S, Jadrić R. Methylenetetrahydrofolate Reductase gene polymorphism in patients receiving hemodialysis. Bosn J Basic Med Sci 2010; 10 Suppl 1:S91-5. [PMID: 20433440 DOI: 10.17305/bjbms.2010.2656] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022] Open
Abstract
Methylenetetrahydrofolate Reductase (MTHFR) is key enzyme in metabolism of homocysteine. Homozygotes for mutation (TT genotype) have hyperhomocysteinemia, risk factor for atherosclerosis development. The aim of the study was to find out distribution of genotype frequencies of C677T MTHFR among patients on maintenance hemodialysis. Possible association of alleles and genotypes of C677T polymorphism of the MTHFR gene with age of onset, duration of dialysis and cause of kidney failure was studied also. Cross-sectional study includes 80 patients from Clinic of Hemodialysis KUCS in Sarajevo. In order to perform genotyping, isolated DNA was analyzed by RFLP-PCR and gel-electrophoresis. From total of 80 patients, 42.5% (n=24) were female, 57.5% (n=46) were male, mean age 54.59+/-1.78 years and duration of dialysis 79.92+/-6.32 months. Genotype distribution was: CC 51.2% (n=41), CT 37.5% (n=30) and TT 11.2% (n=9). Patients with wild-type genotype have longer duration of dialysis in month (87.1 +/- 63.93) comparing to TT genotype patients (67.06 +/- 39.3), with no statistical significance. T allele frequency was significantly higher in group of vascular and congenital cause of kidney failure (Pearson X2 =6.049, P<0.05) comparing to inflammation etiology group. Genotype distribution results are within the results other studies in Europe. Obtained results indicate that C677T polymorphism is not associated with onset, duration and cause of kidney failure in our hemodialysis population. There is an association of T allele of the MTHFR gene and vascular and congenital cause kidney failure.
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Affiliation(s)
- Emina Kiseljaković
- Department of Medical Biochemistry, Faculty of Medicine, University of Sarajevo, Cekalusa 90, Sarajevo, Bosnia and Herzegovina
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Sottilotta G, Siboni SM, Latella C, Oriana V, Romeo E, Santoro R, Consonni D, Trapani Lombardo V. Hyperhomocysteinemia and C677T MTHFR genotype in patients with retinal vein thrombosis. Clin Appl Thromb Hemost 2009; 16:549-53. [PMID: 19825913 DOI: 10.1177/1076029609348644] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
INTRODUCTION Elevated homocysteine (Hcy) is associated with the risk of deep vein thrombosis, pulmonary embolism, ischemic heart disease, and stroke. Several studies have suggested that hyperhomocysteinemia (HHcy) may predispose to retinal vein thrombosis (RVT) development. The aim of this study is to investigate the relationship between Hcy, C677T methylenetetrahydrofolate reductase (MTHFR) genotype, and RVT in patients compared with controls. MATERIALS AND METHODS We evaluated the Hcy plasma level of 3114 consecutive participants in 2 Italian centers during a 2-year period. Hyperhomocysteinemia was found in 99 patients and 136 healthy participants. Of the 99 patients, 20 had RVT with a high prevalence of HHcy in the RVT subgroup (20.2%). This result suggested a possible relationship between HHcy and RVT development. We investigated 105 consecutive patients with recent diagnosis of RVT, and we compared them with 226 healthy controls to evaluate whether HHcy may be a risk factor for RVT. RESULTS the prevalence of HHcy was higher in patients compared with controls (34.3% vs 14.2%; P < .001). The MTHFR C677T genotype was found in 69 of 105 (65.7%) patients with RVT (heterozygosity: 40 of 105 and homozygosity: 29 of 105). The control group showed the presence of MTHFR C677T genotype in 169 of 226 participants (74.8%; heterozygosity: 100 of 226 and homozygosity: 69 of 226) without difference between the 2 groups (P = .08). CONCLUSION our study suggests that HHcy is a possible risk factor for RVT development, while no association was found between RVT and the C677T MTHFR genotype.
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Affiliation(s)
- Gianluca Sottilotta
- Hemophilia Centre, Hemostasis and Thrombosis Service, Azienda Ospedaliera "Bianchi-Melacrino-Morelli", Reggio Calabria, Italy.
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Endothelial nitric oxide synthetase, methylenetetrahydrofolate reductase polymorphisms, and cardiovascular complications in Tunisian patients with nondiabetic renal disease. Clin Biochem 2009; 42:958-64. [DOI: 10.1016/j.clinbiochem.2009.04.005] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2008] [Revised: 04/04/2009] [Accepted: 04/11/2009] [Indexed: 11/18/2022]
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Prevalence of methylenetetrahydrofolate gene (MTHFR) C677T polymorphism among chronic hemodialysis patients and its association with cardiovascular disease: a cross-sectional analysis. Clin Exp Nephrol 2009; 13:501-507. [PMID: 19466593 DOI: 10.1007/s10157-009-0194-2] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2008] [Accepted: 04/17/2009] [Indexed: 10/20/2022]
Abstract
INTRODUCTION Cardiovascular disease (CVD) remains the main cause of morbidity and mortality in end stage renal disease (ESDR) patients. A common C-T mutation at nucleotide position 677 (C677T) has been identified in the gene coding for methylenetetrahydrofolate reductase (MTHFR), which is involved in the remethylation of homocysteine (Hcy). The C677T mutation decreases MTHFR activity, tends to increase Hcy concentrations in individuals who are homozygous for the T/T genotype, and may predispose to CVD. Recent reports suggested that the T/T genotype may predispose type 2 diabetic and hypertensive patients to the development of progressive renal insufficiency. The aim of this cross-sectional study is to analyze the prevalence of the MTHFR C677T gene polymorphism among a group of chronic dialysis patients in comparison to age- and gender-matched controls. We also examined the possible association between CVD and MTHFR gene mutation in this group of patients. PATIENTS AND METHODS Fifty chronic hemodialysis patients were included in the study. They were 29 males and 21 females with a mean age of 41.57 +/- 11.76 years. Three patients (6%) were diabetic (type 2). Mean duration of dialysis was 6.4 +/- 3.2 years (range 1-15 years). CVD was defined as being present if there was a medical history of coronary artery disease, cerebrovascular stroke or transient ischemic attacks. MTHFR C677T gene polymorphism was analyzed by PCR in order to discriminate between homozygous (C/C and T/T) and heterozygous (C/T) genotypes. We also measured serum vitamin B(12), folate, total plasma Hcy (tHcy), lipid profile and serum albumin concentrations in the study group. Thirty healthy subjects (16 males and 14 females with mean age of 37.42 +/- 7.63 years) served as healthy controls. RESULTS Thirteen patients (26%) experienced at least one cardiovascular event: two (4%) had a history of ischemic cerebrovascular disease, 13 (26%) had coronary artery disease, and one patient (2%) had myocardial infarction. The C677T mutation of MTHFR was not found to be different in hemodialysis patients and healthy controls. Thirty dialysis patients (60%) and 19 healthy subjects (63.33%) had only the wild-type allele (C/C), 16 dialysis patients (32%) and nine healthy controls (30%) had one T allele (C/T), and four dialysis patients (8%) and two healthy controls (6.67%) had two copies (T/T) of the T allele. There were no differences between patients with the three different MTHFR genotypes (C/C, C/T, T/T) regarding cardiovascular events or cardiovascular risk factors. Age, gender, percentages of diabetic and hypertensive patients, serum folate, vitamin B(12), lipid profile, and tHcy levels were not significantly different between the three groups (P > 0.05). Hemodialysis patients with CVD were significantly older compared to those without CVD (P = 0.02). Diabetes status was significantly associated with cardiovascular events (P = 0.01). CONCLUSIONS In the dialysis population that we studied, MTHFR C677T gene polymorphism occurred in a pattern similar to that seen for age- and gender-matched healthy controls. No significant association was detected between the T/T genotype and CVD in dialysis patients. Plasma total homocysteine levels were not affected by mutation of the gene coding for MTHFR, and this may be explained by the normal serum folate and vitamin B(12) levels found in the study group.
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Jamison RL, Shih MC, Humphries DE, Guarino PD, Kaufman JS, Goldfarb DS, Warren SR, Gaziano JM, Lavori P. Effect of the MTHFR C677T and A1298C polymorphisms on survival in patients with advanced CKD and ESRD: a prospective study. Am J Kidney Dis 2009; 53:779-89. [PMID: 19272686 DOI: 10.1053/j.ajkd.2008.12.023] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2008] [Accepted: 12/30/2008] [Indexed: 01/20/2023]
Abstract
BACKGROUND Abnormalities in the gene regulating methylenetetrahydrofolate reductase (MTHFR) are associated with increased homocysteine levels and increased mortality in normal and chronic kidney disease (CKD) populations. STUDY DESIGN Gene association study. SETTING & PARTICIPANTS This was a substudy of 677 patients from 21 Veterans Affairs medical centers participating in a randomized clinical trial (Homocysteinemia in Kidney and End-Stage Renal Disease [HOST]) of the effect on all-cause mortality of vitamin-induced lowering of plasma homocysteine levels. Of 677 patients, 213 (31%) were treated by using dialysis (end-stage renal disease [ESRD]) and 464 (69%) had a Cockcroft-Gault estimated creatinine clearance less than 30 mL/min (advanced CKD). PREDICTOR Polymorphisms C677T (rs1801133) and A1298C (rs1801131) of the MTHFR gene. OUTCOMES Unadjusted and adjusted all-cause mortality. MEASUREMENTS DNA was extracted from blood samples and amplified by means of polymerase chain reaction. RESULTS The adjusted hazard ratio in a recessive model of the relationship between the C677T polymorphism and all-cause mortality in all patients was 1.47 (95% confidence interval, 1.00 to 2.16; P = 0.05). In patients with ESRD with the mutant TT genotype, the adjusted hazard ratio for mortality in all patients was 2.27 (95% confidence interval, 1.07 to 4.84; P = 0.03); patients with advanced CKD showed a similar, although not significant, trend. The risk of myocardial infarction (P = 0.05) and composite risk of myocardial infarction, stroke, lower-extremity amputation, and mortality (P = 0.02) were greater in patients with ESRD with the mutant T allele at nucleotide 677. The overall relationship between the A1298C polymorphism and mortality was not significant (P = 0.6). LIMITATIONS Participants were 98% men; DNA samples were not obtained at enrollment in HOST; linkage disequilibrium with another causal polymorphism is a potential confounding factor; and power was reduced by the limited number of participants. CONCLUSIONS These findings provide additional support for the hypothesis that the mutant TT genotype at nucleotide 677 of the gene regulating MTHFR activity may increase the mortality risk in patients with ESRD.
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Affiliation(s)
- Rex L Jamison
- Veterans Affairs Palo Alto Health Care System, Palo Alto, CA 94304, USA.
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Abstract
Bone tissue quality is determined not only by multiple architectural variables, but also by the mechanical properties of collagen type 1. Homocysteinuria is a genetic disease whose manifestations include severe hyperhomocysteinemia and decreased bone strength. The effects of smaller homocysteine elevations on bone tissue are difficult to demonstrate in clinical studies. Studies in animals and in humans suggest that homocysteine may weaken collagen crosslinks and, if present in large amounts, interfere with bone remodeling. Whether routine homocysteine assays should be performed to detect bone frailty remains unclear. In clinical practice, the focus should be on identifying patients with potential causes of homocysteine elevation (e.g., medications), who should then be given vitamin D and folic acid supplementation if needed. This approach may improve not only bone health, but also vascular and general health.
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Affiliation(s)
- Régis Levasseur
- Service de Rhumatologie et Pôle ostéo-articulaire, CHU d'Angers, Inserm U922, Faculté de Médecine d'Angers, 49933 Angers Cedex, France.
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Suliman ME, Lindholm B, Bárány P, Qureshi AR, Stenvinkel P. CARDIOVASCULAR AND SURVIVAL PARADOXES IN DIALYSIS PATIENTS: Homocysteine-Lowering Is Not a Primary Target for Cardiovascular Disease Prevention in Chronic Kidney Disease Patients. Semin Dial 2007; 20:523-9. [DOI: 10.1111/j.1525-139x.2007.00336.x] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
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Zoccali C, Testa A, Spoto B, Tripepi G, Mallamaci F. Mendelian randomization: a new approach to studying epidemiology in ESRD. Am J Kidney Dis 2006; 47:332-41. [PMID: 16431263 DOI: 10.1053/j.ajkd.2005.10.027] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2005] [Revised: 10/25/2005] [Accepted: 10/25/2005] [Indexed: 11/11/2022]
Abstract
Associations between environmental exposures and disease in epidemiological studies often are confounded and may result in erroneous interpretations. The random assortment of genes from parents to offspring at gamete formation--Mendelian randomization--is emerging as a useful method for studying the nature (causal or not) of environmental exposures. This occurs because the association between a disease and a polymorphism that mimics the biological link between a given exposure and the same disease is unaffected by the reverse causation that may complicate the interpretation of observational studies. Thus, similarly to randomized trials, association studies between gene polymorphisms with a well-established function may be useful for excluding confounding as an explanation for a given epidemiological relationship. The rationale behind this concept is that transmission of genes occurs in a random way; therefore, offspring have an equal chance of inheriting either of the 2 alleles that their parents have at any particular locus, a phenomenon independent from environmental factors. This is similar to the construct of randomized trials, in which randomization is expected to produce similar distributions of measured and unmeasured confounders between treated and untreated (control) groups. The equivalence between random assortment of alleles and random assignment of interventions in randomized studies is particularly useful because it may give a clue for interpreting associations that may be produced as both the effect of a gene or result of an environmental exposure. Examples are provided about the use of this concept to elucidate paradoxical inverse associations in epidemiological studies in the general and end-stage renal disease populations.
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Affiliation(s)
- Carmine Zoccali
- Consiglio Nazionale delle Ricerche-Istituto di Biomedicina, Clinical Epidemiology of Renal Diseases and Hypertension, Reggio Cal, Italy.
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Winkelmayer WC, Kramar R, Sunder-Plassmann G, Födinger M. Effects of single-nucleotide polymorphisms in MTHFR and MTRR on mortality and allograft loss in kidney transplant recipients. Kidney Int 2005; 68:2857-62. [PMID: 16316363 DOI: 10.1111/j.1523-1755.2005.00759.x] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
BACKGROUND Plasma total homocysteine (tHcy) is associated with cardiovascular outcomes in kidney transplant recipients (KTR). The methylenetetrahydrofolate-reductase (MTHFR) 677C>T polymorphism, an important determinant of plasma tHcy concentrations, could therefore constitute an important prognostic marker. METHODS We prospectively followed 710 KTR over >6 years. The MTHFR677C>T, MTHFR1298A>C, MTHFR1793G>A, and MTRR66A>G polymorphisms were analyzed. Demographic, clinical, and transplant-related information was obtained, and patients were followed-up using the Austrian Dialysis and Transplant Registry. Using Cox regression, we established the independent relations of each genotype to the risk of death from any cause, and/or kidney allograft loss. RESULTS During a median follow-up of 6.1 years, 154 participants died and 260 kidney allografts were lost. Compared to patients with the MTHFR677CC genotype, patients with MTHFR677CT had an adjusted relative mortality risk of 1.02 (95%CI 0.70-1.47), and those with MTHFR677TT of 0.98 (95%CI 0.52-1.85). Compared to MTHFR677CC, the relative risks of kidney allograft loss were 0.93 (95%CI 0.70-1.23; MTHFR677CT) and 0.78 (95%CI 0.47-1.30; MTHFR677TT), respectively. None of the other genotypes were associated with the risks studied, either. These findings did not depend on whether we controlled for tHcy levels. CONCLUSION This study does not support the routine use of MTHFR or MTRR genotyping for prognostic evaluation or risk-stratification in kidney transplant recipients.
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Affiliation(s)
- Wolfgang C Winkelmayer
- Division of Pharmacoepidemiology and Pharmacoeconomics, Department of Medicine, Brigham and Women's Hospital, Harvard Medical School, Boston, Boston, MA 02120, USA.
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