Polymorphisms of the methylenetetrahydrofolate reductase gene and clinical outcomes in HLA-matched sibling allogeneic hematopoietic stem cell transplantation

To evaluate whether the C677T and A1298C polymorphisms of 5,10-methylenetetrahydrofolate reductase (MTHFR) are related to the toxicity of methotrexate (MTX) used in allogeneic stem cell transplantation, we performed association analysis between these genetic polymorphisms and the clinical outcomes of patients treated using human leukocyte antigen-matched sibling stem cell transplantation. Patients (n=72) with hematological malignancy or aplastic anemia were given a short course of MTX as a graft-versus-host disease prophylaxis. Patients with the 677TT genotype showed higher total bilirubin levels (677TT vs 677CT vs 677CC, 14.5 vs 8.6 vs 3.8 mg/dl, respectively; p=0.07) and higher aspartic transaminase levels (677TT vs 677CT vs 677CC, 678.9 vs 156.6 vs 111.8 IU/l; p=0.04). Platelet recovery to 20,000/μl was slower for patients with the 677TT genotype than for patients with other genotypes (677TT, 59 days; 677CT, 26 days; 677CC, 26 days; p=0.0075). The influences of the C677T polymorphism on treatment-related mortality (TRM) were also analyzed. One-year cumulative TRMs for patients with the TT genotype and the other genotypes were 66 and 30% (p=0.04) and their respective 1-year overall survivals were 30 and 56% (p=0.11). No association was observed between the A1298C polymorphism and clinical outcome for any of the different genotypes. Therefore, patients at high risk of developing hepatic toxicity and with a poor likelihood of survival could be selected by genotyping MTHFR C677T before allogeneic stem cell transplantation.     

MTHFR C677T基因多态性与新疆哈族和汉族食管癌易感性的关系

目的:探讨亚甲基四氢叶酸还原酶(MTHFR) 基因C677T多态性与新疆哈族、汉族食管癌易感性的关系．方法:用PCR-RFLP方法检测食管癌患者178 例(哈萨克族94例,汉族84例)和同一地区无肿瘤病史的正常对照者155例(哈萨克族98例,汉族57例)的MTHFR基因C677T基因型分布．结果:新疆哈族食管癌组中MTHFR C677T 3种基因型CC,CT,TT,所占比例分别是 56．4％,36．2％,7．4％,与新疆汉族食管癌组中的32．9％,40．0％,27．1％相比,存在显著差异(X2=1 5．37,P<0．05);哈族正常对照组分别为58．2％,29．6％,12．2％与汉族正常对照组 22．8％,52．6％,24．6％相比,有显著差异(X2= 18．26,P<0．05)．MTHFR 3种基因型在哈族食管癌组中的分布(CC 56．4％,CT 36．2％and TT 7．4％)与对照组中(CC 22．8％,CT 52．6％and TT 24．6％)相比,无显著差异(X2=1．776,P= 0．412)．在汉族食管癌组与对照组间也无显著差异(X2=2．750,P=0．253)．结论:MTHFR C677T基因多态性分布在新疆哈族、汉族正常对照组间存在民族差异,在食管癌间也存在差异．MTHFR C677T基因多态性可能与新疆哈萨克族与汉族食管癌的易感性无关．     

C677T gene polymorphism of methylenetetrahydrofolate reductase (MTHFR) in patients with myocardial infarction

Hyperhomocysteinemia is thought to be an independent risk factor for coronary heart disease. Increased plasma homocysteine level can result from malnutrition (e.g. folate deficiency) and/or genetic-related disturbances. Methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in the synthesis of 5-methyltetrahydrofolate, the methyl donor for homocysteine remethylation to methionine. Transition of cytosine (C) to thymidine (T) at nucleotide position 677 of MTHFR gene causes alanine 226-to-valine substitution, and in consequence results in decreased enzyme activity and increased homocysteine level. Therefore, the aim of our study was to estimate the frequency distribution of C677T MTHFR polymorphism in patients with past myocardial infarction (MI), and to evaluate the association between this polymorphism and age of MI onset or left ventricular mass (LVM). The study was performed in 100 MI patients aged from 34 to 76 years and in control group consisted of 100 age- and gender-matched non-MI subjects. Applying PCR followed by Hinf I digestion of amplification products no significant difference in the frequency distribution of C677T MTHFR genotypes has been found between both groups (MI patients: 46% CC, 45% CT and 9% TT, and control group: 39% CC, 50% CT and 11% TT, respectively). No significant association between MTHFR genotypes and age of MI onset or LVM has been found in MI group. The results of our study suggest that C677T polymorphism of MTHFR gene is not a risk factor for myocardial infarction in Polish population.     

动脉粥样硬化性脑梗死患者血浆同型半胱氨酸水平及亚甲基四氢叶酸还原酶基因多态性

目的 探讨血浆同型半胱氨酸水平、亚甲基四氢叶酸还原酶基因多态性与动脉粥样硬化性脑梗死之间的关系.方法 选择性别、年龄匹配的动脉粥样硬化性脑梗死患者(脑梗死组)68例及对照组50例,采用荧光偏振免疫法测定血浆同型半胱氨酸水平,聚合酶链反应-限制性片长多态性技术检测亚甲基四氢叶酸还原酶基因多态性.结果 脑梗死组TT基因型(36.8%比16.0%)及T等位基因频率(59.6%比38.0%)均显著高于对照组(P<0.05).脑梗死组血浆同型半胱氨酸水平显著高于对照组(P<0.05).脑梗死组和对照组亚甲基四氢叶酸还原酶 677TT纯合子血浆同型半胱氨酸水平均显著高于CT型和CC型者(P<0.05).结论 血浆同型半胱氨酸水平升高是动脉粥样硬化性脑梗死的危险因素.亚甲基四氢叶酸还原酶 C677T基因多态性与血浆同型半胱氨酸水平密切相关,与动脉粥样硬化性脑梗死显著相关.     

Relationship between genetic polymorphism of MTHFR C677T and lower extremities deep venous thrombosis

Objective: To investigate the association between the polymorphism of methylenetetrahydrofolate reductase (MTHFR) gene and the formation of lower extremities deep venous thrombosis, and to evaluate the etiology of deep venous thrombosis.

Methods: Polymorphisms of the 677th site C/T in MTHFR gene for 101 patients with lower extremities deep venous thrombosis (DVT group) and 120 healthy subjects (control group) were detected by polymerase chain reaction with sequence-specific primers. Genotype and allelic frequencies were compared between the two groups.

Results: Genotype frequencies of CC, CT and TT in MTHFR C677?T were 41.58, 25.74 and 32.67% in DVT group, and 58.33, 23.33 and 18.33% in control group, respectively. There was a significant difference in TT genotype frequency between the two groups (P <0.05).

Conclusion: The frequency of MTHFR 677TT genotype may be correlated with the morbility of DVT.     

内皮型一氧化氮合酶和N5，N10-亚甲基四氢叶酸还原酶基因多态性与苏皖地区汉族人群早发冠心病易感性的相关关系

目的 探讨内皮型一氧化氮合酶(eNOS)基因第7外显子G894T突变和N5,N10-亚甲基四氢叶酸还原酶(MTHFR)基因C677T突变与苏皖地区汉族人群早发冠心病(PCAD)发病的关系.方法 采用病例对照研究的方法,应用聚合酶链反应-限制性片长多态性(PCR-RFLP)技术,分别检测131例PCAD患者(PCAD组)和131例年龄、性别相匹配的无冠心病者(对照组)的eNOS和MTHFR基因的单核苷酸多态性,判定其基因型并统计各基因型及等位基因的频率.结果 eNOS基因G894T多态性在PCAD组和对照组中的基因型分布(x2=2.072,P=0.355)和T等位基因频率(x2=0.727,P=0.394)差异均无统计学意义.MTHFR基因C677T基因型在PCAD组CT和TT型分布均高于对照组(x2 =14.290,P=0.001),T等位基因频率亦高于对照组(x2=16.339,P =0.000),差异有显著性(P＜0.05).Logistic回归分析显示,携带MTHFR基因C677TTT基因型是PCAD发病的独立危险因素.结论 eNOS基因G894T多态性可能与苏皖地区汉族人群PCAD发病无关;MTHFR基因677C/T多态性的TT基因型可能增加苏皖地区汉族人群PCAD的患病风险,T等位基因可能是PCAD的遗传易感基因.     

The MTHFR CT polymorphism confers a high risk for stroke in both homozygous and heterozygous T allele carriers with Type 2 diabetes.

OBJECTIVE: Individuals with Type 2 diabetes are at increased risk of stroke. Plasma homocysteine (tHcy) is an independent risk factor for cardiovascular (CV) disease. The methylene-tetrahydrofolate reductase (MTHFR) gene polymorphism (thermolabile variant C(677)T) is associated with CV risk, partly as a result of increased Hcy, especially in homozygous subjects. AIM: To relate the occurrence of the MTHFR polymorphism with stroke prevalence by examining allelic frequency and genotype distribution in 165 subjects with Type 2 diabetes studied for the presence of thermolabile C(677)T MTHFR mutation. RESULTS: Mean age was 67.7 years, and tHcy 18.2 micromol/l. T allele frequency was 38.5%. MTHFR genotypes were: normal (CC) 40%; heterozygous (CT) 43%; homozygous (TT) 17%. Serum levels of folic acid and B12 vitamin were within normal limits. Stroke prevalence was 14%. Sixty-four per cent of stroke-free subjects had the normal C allele vs. 46% in stroke subjects. The frequencies of genotypes (CC-CT-TT) were (%): 44-41-15 in stroke-free vs. 17-57-26 in stroke patients. Coronary (CAD) and peripheral artery disease (PAD) were common in all groups, with no differences according to genotypes. Stroke prevalence was markedly higher in genotypes CT and TT (18 and 21%) compared with CC (6%). Mean tHcy levels were higher in TT subjects. CONCLUSION: The allelic frequency of C(677)T MTHFR mutation in Type 2 diabetes subjects with stroke is markedly different from that of subjects without stroke. Genotypic characteristics suggest that C(677)T MTHFR mutation confers a higher risk for stroke to both homozygous and heterozygous T allele carriers that cannot be ascribed solely to raised tHcy and/or lower folate status in CT subjects, nor to phenotypic expression of conventional risk factors for stroke. The impact of the MTHFR polymorphism on stroke may result from T allele-linked deleterious effects, or C allele-linked protection. Confirmatory studies are warranted, as this cohort was not randomly selected, and a type 1 error cannot be ruled out.     

Genetic polymorphism of methylenetetrahydrofolate reductase as a risk factor for diabetic nephropathy in Chinese type 2 diabetic patients

OBJECTIVE: Genetic predisposition has been implicated in diabetic nephropathy (DN). The C677T variant of the methylenetetrahydrofolate reductase (MTHFR) gene, one of the key enzymes catalyzing remethylation of homocysteine, may play a role in the development of not only vascular disease but also diabetic microangiopathies. In this study, we examined the distribution of the MTHFR genotypes in the Chinese population and the association between the C677T variant and diabetic nephropathy. METHODS: 220 unrelated patients with type 2 diabetes mellitus and 130 controls were recruited. The MTHFR genotype was analyzed by PCR followed by HinfI digestion. Plasma total homocysteine levels were measured using high-performance liquid chromatography (HPLC) with fluorescence detection. RESULTS: In 130 healthy control subjects, the frequency of the mutant T allele was 30.0%, comparable to that of a Hong Kong (Chinese) population. The distribution of the three genotypes was as follows: TT genotype, 16.9%; CT genotype, 26.2%; and CC genotype, 56.9%. This genotype distribution did not differ between control subjects and type 2 diabetic patients in which 19.1% were TT, 34.5% were CT and 46.4% were CC (2=3.85, P>0.05). The frequency of the mutant T allele was 42.3% in diabetic patients with nephropathy (n=124) versus 28.6% in those without nephropathy (n=96). The genotype frequencies were TT, 21.0%; CT, 42.7%; CC, 36.3% in diabetic patients with nephropathy versus TT, 16.7%; CT, 23.9%; CC, 59.4% in those without nephropathy. The MTHFR genotype and allele frequencies were different between diabetic patients with and without nephropathy (chi2=12.27, P<0.005; chi2=8.77, P<0.005, respectively). Moreover, plasma homocysteine levels were markedly higher in individuals with TT genotype than those with CC or CT genotype. CONCLUSIONS: The C677T mutation of MTHFR gene is common in the Chinese population. MTHFR C677T gene polymorphism associated with a predisposition to increased plasma homocysteine levels may represent a genetic risk factor for diabetic nephropathy in Chinese type 2 diabetic patients.     

The relationship of the methylenetetrahydrofolate reductase C677T gene polymorphism in Turkish type 2 diabetic patients with and without nephropathy

BACKGROUND: Poor glycaemic control, hypertension and duration of diabetes are risk factors for the development of diabetic nephropathy, but there may be genetic factors. Recently, a common C to T mutation at nucleotide position 677 of the MTHFR gene (MTHFR677C > T) has been reported to be correlated with hyperhomocysteinemia and the severity of coronary artery disease as macroangiopathy. We aim to investigate Turkish type 2 diabetic patients with/without diabetic nephropathy and healthy group and examine the contribution of the MTHFR gene polymorphism to the development of diabetic nephropathy. METHODS: DNA was extracted from peripheral leukocytes of the subjects. Genotyping of the MTHFR C677T polymorphism for all individuals was performed by melting curve analysis of the generated amplicons after real-time online PCR. RESULTS: This genotype distribution did not differ between control subjects and type 2 diabetic patients in which 6.8% were TT, 43.7% were CT and 49.5% were CC (chi2 = 0.201, p > 0.05). The frequency of the mutant T allele was 23.4% in diabetic patients with nephropathy versus 33.0% in those without nephropathy. The genotype frequencies were TT, 2.1%; CT, 46.6%; CC, 55.3% in diabetic patients with nephropathy versus TT, 10.7%; CT, 44.6%; CC, 44.6% in those without nephropathy. CONCLUSIONS: The MTHFR genotype and allele frequencies were not different between diabetic patients with and without nephropathy (chi2 = 3, 386, p > 0.005; chi2 = 2.320, p > 0.005, respectively). Therefore, we conclude that the MTHFR gene polymorphism is not associated with the development of diabetic nephropathy in Turkish type 2 diabetic patients.     

H型高血压患者基因型与叶酸补充治疗的相关性

目的探讨不同基因型H型高血压患者血压及血浆同型半胱氨酸(homocysteine,Hcy)水平有无差异;在充分应用降压药物控制血压的同时给予叶酸补充治疗,观察治疗前后血浆Hcy及血压水平变化有无差异。方法通过Hcy检测确诊为H型高血压的患者166例入选。叶酸补充治疗前测定血浆Hcy水平,采集既往史、历史最高血压水平等,并行MTHFR(亚甲基四氢叶酸还原酶)677C/T基因型检测,根据检测结果进行分组,为CC组(野生型)、CT组(杂合型)、TT组(突变型)。所有患者在原有降压方案的基础上加用叶酸片0.8 mg 1/日,3月后测定患者血浆Hcy及血压水平。结果 1MTHFR 677C/T基因型检测结果:其中CC型42例,占25.3%,CT型42例,占25.3%,TT型82例,占49.6%。2叶酸治疗前血浆Hcy水平比较:男性高于女性,差异有统计学意义(P0.05);TT组高于CC组及CT组,差异有统计学意义(P0.05);CC组与CT组之间差异无统计学意义(P0.05)。3历史最高血压水平比较:收缩压:CC组高于TT组,差异有统计学意义(P0.05);CC组与CT组之间、CT组与TT组之间差异均无统计学意义(P0.05);舒张压:3组之间差异均无统计学意义(P0.05)。4叶酸补充治疗前后血浆Hcy水平比较:3组患者治疗后血浆Hcy水平均较治疗前降低,差异有统计学意义(P0.05)。5叶酸补充治疗前后血浆Hcy差值比较:TT组高于CC组及CT组,差异有统计学意义(P0.05),CC组与CT组间差异无统计学意义。6叶酸补充治疗前后血压差值比较分析:收缩压:CC组高于TT组,差异有统计学意义(P0.05);CC组与CT组之间、CT组与TT组之间差异均无统计学意义(P0.05);舒张压:三组之间差异均无统计学意义(P0.05)。结论 H型高血压患者基因型与血浆Hcy及历史最高血压水平部分存在差异性。叶酸补充治疗能够有效降低H型高血压患者血浆Hcy水平,并且对MTHFR 677C/T TT可能具有更好的降低Hcy的效果。降压药物联合叶酸补充治疗可能能够更有效地降低MTHFR 677C/T CC基因型H型高血压患者血压水平。     

Hyperhomocysteinemia and the MTHFR C677T polymorphism promote steatosis and fibrosis in chronic hepatitis C patients

The factors and mechanisms implicated in the development of hepatitis C virus (HCV)-related steatosis are unknown. Hyperhomocysteinemia causes steatosis, and the methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism induces hyperhomocysteinemia. We investigated the role of these factors in the development of HCV-related steatosis and in the progression of chronic hepatitis C (CHC). One hundred sixteen CHC patients were evaluated for HAI, fibrosis and steatosis grades, body mass index, HCV genotypes, HCV RNA levels, homocysteinemia, and the MTHFR C677T polymorphism. Hyperhomocysteinemia was associated with the TT genotype of MTHFR (r = 0.367; P = .001). Median values of homocysteine in the CC, CT, and TT genotypes of the MTHFR gene were 9.3, 12.2, and 18.6 micromol/L, respectively (P = .006). Steatosis correlated with the MTHFR polymorphism, homocysteinemia, HAI and fibrosis. Steatosis above 20% was significantly associated with fibrosis. Prevalence and high grade (>20%) of steatosis were 41% and 11% in CC, 61% and 49% in CT, and 79% and 64% in TT, respectively (P = .01). Relative risk of developing high levels of steatosis was 20 times higher for TT genotypes than CC genotypes. According to multivariate analysis, steatosis was independently associated with hyperhomocysteinemia (OR = 7.1), HAI (OR = 3.8), liver fibrosis (OR = 4.0), and HCV genotype 3 (OR = 4.6). On univariate analysis, fibrosis was associated with age, steatosis, MTHFR, homocysteinemia and HAI; however, on multivariate analysis, liver fibrosis was independently associated with age (P = .03), HAI (P = .0001), and steatosis (P = .007). In conclusion, a genetic background such as the MTHFR C677T polymorphism responsible for hyperhomocysteinemia plays a role in the development of higher degree of steatosis, which in turn accelerates the progression of liver fibrosis in CHC.     

MTHFR 677 (C→T) polymorphism is not relevant for prognosis or therapy-associated toxicity in pediatric NHL: results from 484 patients of multicenter trial NHL-BFM 95

We analyzed the relationship of genetic variation within the methylenetetrahydrofolate reductase gene (MTHFR 677 C→T) with clinical characteristics, outcome, and therapy-related toxicity in pediatric non-Hodgkin’s lymphoma (NHL) in our multicenter trial NHL-BFM 95. In this trial, high-dose methotrexate (MTX) infusion regimens were randomized (4- vs 24-h infusion) in patients with B-cell lymphoma; MTX was applied as 24-h infusion in all patients with lymphoblastic lymphoma and anaplastic large cell lymphoma. Toxicity data were collected per patient and therapy course according to National Cancer Institute Common Toxicity Criteria (NCI-CTC). The genotypes in 484 pediatric patients were distributed as follows: MTHFR 677 CC, 206 patients (42.6%); MTHFR 677 CT, 214 patients (44.2%); and MTHFR 677 TT, 64 patients (13.2%). Lymphoblastic lymphoma was significantly associated with homozygosity for the MTHFR 677 T allele. No association of MTHFR 677 genotype with clinical characteristics (sex, age, and tumor stage), outcome, or therapy-related toxicity could be detected. Therefore, we conclude that the MTHFR 677 C→T polymorphism does not appear to influence outcome or therapy-associated toxicity in pediatric patients with NHL treated on BFM protocols.     

A common haplotype on methylenetetrahydrofolate reductase gene modifies the effect of angiotensin-converting enzyme inhibitor on blood pressure in essential hypertension patients--a family-based association study

Our recent study indicated that MTHFR C677T polymorphism may involve in genetic control of blood pressure response to treatment by benazepril, an ACE inhibitor. Currently, we proposed to further investigate whether short-term blood pressure response to benazepril, was modulated by haplotypes re-constructed from both C677T and A1298C polymorphisms in MTHFR gene. A total of 410 hypertensive patients recruited from 344 nuclear families were treated orally with benazepril at a daily dosage of 10 mg for 15 consecutive days. Blood pressures were measured at baseline and on the 16th day of treatment. In addition, 689 family members of these patients were also genotyped. Among these patients, the frequency of MTHFR A1298C AA, AC and CC genotypes was 74.4%, 23.9%, and 1.7%, respectively. The frequency of MTHFR C677T CC, CT and TT genotypes was 23.7%, 51.2%, and 25.1%, respectively. Only three haplotypes, 677T-1298A (50.8%), 677C-1298A (35.7%), and 677C-1298C (13.5%) were re-constructed. Multivariate regression models with generalized estimating equation (GEE) correction detected that the individuals carrying one copy of haplotype 677C-1298C had significantly lower diastolic and systolic blood pressure response (DeltaDBP and DeltaSBP) to benazepril treatment (p= 0.003 and p =0.043, respectively), in comparison to those without haplotype 677C-1298C. The results of family-based association test further confirmed that haplotype 677C-1298C was more frequently transmitted in subjects with either lower residual of DeltaDBP or DeltaSBP. For residual of DeltaDBP, the p-values are 0.007 in an additive model and 0.005 in a dominant model. For residual of DeltaSBP, the p-values are 0.009 in an additive model and 0.006 in a dominant model. Our findings suggest that MTHFR 677C-1298C haplotype modulate blood pressure responsiveness to shortterm treatment of ACE inhibitor in Chinese essential hypertensive patients.     

Methylenetetrahydrofolate reductase gene polymorphisms in essential hypertension relation: with the development of hypertensive end-stage renal disease

BACKGROUND: The pathogenesis of hypertensive nephropathy is multifactoral and in addition to BP, other factors contribute to the development of this renal pathology and its progression to end-stage renal disease. These include genetic predisposition and increased pleasure level of homocysteine-intermediate protein catabolism product known to induce kidney injury. The 677C --> T polymorphism in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene is associated with elevated homocysteine level in the general population, and therefore it has been hypothesized to be a risk factor for the development of renal failure in the course of essential hypertension. METHODS: In this case-control, cross-sectional study the frequency of the MTHFR 677C --> T and the 1298A --> C polymorphism was compared between patients with hypertension-related chronic renal failure (n = 90), patients with essential hypertension without kidney injury (n = 90), and healthy individuals (n = 90) who were matched for age and gender. In addition, the influence of these polymorphisms on homocysteine concentration in individuals with essential hypertension was examined. RESULTS: The frequency of the MTHFR 677 TT genotype did not differ between groups (4.5%, 12.3%, and 11.1%, respectively). Patients with hypertension and the 677TT genotype showed significantly higher homocysteine levels as compared to individuals having CC and CT. In the multivariate correlation analysis the MTHFR 677TT genotype (P < .01; beta = 0.27), age (P < .001; beta = 0.33), and body mass index (P < .01; beta = 0.3) were independent predictors for total homocysteine level. CONCLUSIONS: Plasma homocysteine levels in individuals with essential hypertension is affected by the MTHFR 677C --> T polymorphism. However, we did not prove the hypothesis that MTHFR 677C --> T influences the risk of development of renal failure in the course of hypertension.     

Mutations C677T and A1298C of the 5,10-methylenetetrahydrofolate reductase gene and fasting plasma homocysteine levels are not associated with the increased risk of venous thromboembolic disease.

Mild hyperhomocysteinemia is associated with homozygosity for the thermolabile variant of 5,10-methylenetetrahydrofolate reductase (MTHFR) and could increase the risk of venous thromboembolic disease (VTD). Recently, the second A1298C mutation of the MTHFR gene was described. The present study aimed to analyze both mutations of the MTHFR gene and plasma homocysteine levels in subjects with VTD. The study groups comprised 146 patients with VTD and 100 healthy subjects. There were no statistical differences in carrier frequency and allelic frequency for both A1298C and C677T mutations, nor were there any differences encountered between subjects with VTD and controls in either plasma homocysteine levels or according to C677T or A1298C genotypes of MTHFR. In our VTD patients and controls, neither MTHFR 677CT/1298CC nor MTHFR 677TT/1298CC combined genotypes were observed; double heterozygotes (A1298C/C677T) were represented only in 11% of VTD patients, and in 15% of the controls. In conclusion, the polymorphisms C677T and A1298C of MTHFR and fasting plasma homocysteine levels do not seem to be significant risk factors for venous thromboembolic disease.     

亚甲基四氢叶酸还原酶基因C677T多态与结直肠癌遗传易感性的相关性

目的:探讨亚甲基四氢叶酸还原酶基因(MTHFR)C677T多态与结直肠癌(CRC)遗传易感性的关系.方法:采用TaqMan方法检测CRC 449例与对照672例的MTHFR C677T的基因型分布及差异.以非条件Logistic回归法计算表示相对危险度的比值比(OR)及其95%可信区间(CI).OR值均经性别、年龄、吸烟、饮酒、体质量指数和一级亲属CRC家族史等因素校正.结果:CRC组677T等位基因频率显著低于对照组,其为CRC发生的保护因素(OR:0.70,95%CI:0.58-0.83,P<0.01).与CC纯合子相比,CT杂合子的CRC风险显著降低至0.73倍(95%CI:0.56-0.95,P<0.05),而TT纯合子的CRC风险进一步降至0.47倍(95%CI:0.33-0.68,P<0.01).在非饮酒人群中,C677T的CRC风险保护效应略有增强;而在饮酒人群中,CT和TT基因型携带者的CRC发病风险虽仍低于CC基因型携带者,但差异无统计学意义.在CRC人群中,荷大肿瘤(最大直径>4cm)者携带TT基因型的比例高于荷小肿瘤者(16.3% vs 8.3%,P<0.05);荷黏液腺癌者携带TT基因型的比例高于荷乳头状腺癌及管状腺癌者(22.2% vs 17.1%,10.3%,P=0.084).结论:MTHFR C677T降低CRC发病风险,饮酒可能削弱该多态的CRC风险保护效应.TT基因型可能与CRC肿瘤进展有关.     

亚甲基四氢叶酸还原酶基因多态性与原发性高血压患者合并冠心病的相关性研究

目的探讨N5,10-亚甲基四氢叶酸还原酶(MTHFR)C677T位点突变与河南豫北地区原发性高血压及其合并冠心病发病的关系。方法选择原发性高血压患者405例为高血压组,高血压合并冠心病患者400例为冠心病组,健康体检者400例为对照组。对3组MTHFR基因C677T多态性进行基因分型。结果冠心病组T等位基因频率和TT基因型频率明显高于高血压组和对照组(P<0.05)。冠心病组TT基因型患者TC和血浆同型半胱氨酸水平明显高于CC+CT基因型(P<0.05)。结论 MTHFR基因C677T多态性与原发性高血压患者冠心病的发生相关。     

MTHFR C677T Polymorphism and Risk of HCC in Patients With Liver Cirrhosis: Role of Male Gender and Alcohol Consumption

Background:  A single nucleotide polymorphism (SNP) C677T in the methylenetetrahydrofolate reductase (MTHFR) gene has been identified. The TT or CT genotypes show a marked reduction of the enzyme activity; this causes higher homocysteine levels and alterations of folate metabolism. Folate metabolism is essential for DNA synthesis and methylation, crucial steps in carcinogenesis. In this paper, we investigated whether the MTHFR C677T SNP could influence the occurrence of hepatocellular carcinoma (HCC) in a cohort of patients transplanted for end stage liver disease of different etiologies.
Methods:  Two hundred and twelve consecutive patients who underwent liver transplantation for end stage liver disease due to hepatitis B or C, alcoholic liver disease, and other causes were studied. Two hundred and thirty-six blood donors served as controls. Focal hepatic lesions were searched in the sectioned explanted livers. The presence of the MTHFR C677T SNP was determined via polymerase chain reaction amplification.
Results:  Among the 65 patients with HCC, 22 had the CC genotype, 30 the CT, and 13 the TT genotype. Only in patients with alcoholic liver disease was a significant association detected between the TT genotype and the presence of liver cancer (6/17 vs. 5/46, p  < 0.05). At stepwise logistic regression analysis the independent selected predictors of HCC were found: age at transplantation >55 years ( p  < 0.001) and the association among male gender, alcoholic liver disease, and MTHFR TT genotype ( p  = 0.002).
Conclusions:  The present study suggests that male TT carriers with alcoholic cirrhosis bear an increased risk of developing HCC.     

Methylenetetrahydrofolate reductase genotypes and predisposition to atherothrombotic disease; evidence that all three MTHFR C677T genotypes confer different levels of risk.

AIMS: Elevated plasma homocysteine is an independent risk factor for atherothrombotic disease. Individuals homozygous for the methylenetetrahydrofolate reductase (MTHFR) 677C allele exclusively accumulate 5methyltetrahydrofolate, the methyl donor for homocysteine remethylation, in their red blood cells; this contrasts with 677 TT homozygotes who also accumulate significant levels of non-methylated folate derivatives. Those with the MTHFR 677 TT, CT and CC genotypes may therefore differ qualitatively with respect to folate utilization and hence their capacity to remethylate homocysteine. This study was consequently designed to establish whether all three genotypes confer different levels of atherothrombotic risk. METHODS AND RESULTS: The risk of atherothrombotic disease conferred by the MTHFR 677 CT and 677 CC genotypes was assessed using a 'restricted' meta-analysis approach applied to subjects from the first ten studies reporting a significantly increased risk conferred by the 677 TT genotype. The defined risk of the TT genotype in each of these ten studies was judged by us to denote 'genetic vulnerability' in the populations from which subjects were drawn. After proportional adjustment for the greater number of case TT homozygotes, the CT and CC frequencies observed in cases were compared with expectations based on the frequencies of these genotypes in controls. The observed CT frequency among cases was higher than expected in eight of the ten studies. In the meta-analysis, which included 1857 cases and 2942 controls, 847 (45.6%) cases, instead of the 777 (41.8%) expected, had the MTHFR CT genotype (P=0.010). CONCLUSIONS: Our findings suggest that the three MTHFR C677T genotypes confer different levels of atherothrombotic risk in 'genetically vulnerable' populations: CT heterozygotes have an elevated risk over CC homozygotes. One explanation is that the CT genotype actively confers atherothrombotic risk. An alternative interpretation however, for which a biologically plausible mechanism is proposed, is that CC is a protective genotype.     

Methylenetetrahydrofolate reductase polymorphism associated with susceptibility to coronary heart disease in Chinese type 2 diabetic patients

OBJECTIVE: Epidemiological studies have identified hyperhomocyst(e)inemia as an independent risk factor for atherosclerosis. The C677T variant of the methylenetetrahydrofolate reductase (MTHFR) gene, one of the key enzymes catalyzing remethylation of homocysteine, might play a role in the development of coronary heart disease (CHD). In this study, we examined the distribution of the MTHFR genotypes in the Chinese population and the association between the C677T variant and CHD in Chinese type 2 diabetic patients. METHODS: Two hundred and twenty-eight unrelated patients with type 2 diabetes mellitus (126 with coronary heart disease) and 114 healthy control subjects were recruited. The MTHFR genotype was analyzed by PCR followed by HinfI digestion. Plasma total homocysteine levels were measured using high-performance liquid chromatography (HPLC) with fluorescence detection. RESULTS: In 114 healthy control subjects, the frequency of the mutant T allele was 38.0%, comparable to that of a Hong Kong (Chinese) population. The genotype distribution did not differ between control subjects and type 2 diabetic patients (chi(2) = 3.67, P > 0.05). Genotypic analysis revealed that type 2 diabetic patients with CHD displayed a greater prevalence of T allele (45.2%) than type 2 diabetic patients without CHD (30.4%) (chi(2) = 8.72, P < 0.005). The odds ratio for CHD in type 2 diabetic patients in presence of T allele was 1.89 (CI 95%, 1.24-2.88). The MTHFR genotype were different between diabetic patients with and without CHD (chi(2) = 11.98, P < 0.005). Moreover, plasma homocysteine levels were markedly higher in individuals with TT genotype than those with CC or CT genotype or CC plus CT genotype. CONCLUSIONS: The C677T mutation of MTHFR gene is common in the Chinese population. MTHFR C677T gene polymorphism associated with a predisposition to increased plasma homocysteine levels could constitute a useful predictive marker for CHD in Chinese type 2 diabetic patients.