亚甲基四氢叶酸还原酶基因多态性与糖尿病肾病相关性研究

目的：研究亚甲基四氢叶酸还原酶（MTHFR）基因多态性与2型糖尿病肾病的关系。方法：运用聚合酶链反应－限制性片段长度多态性技术（PCR－RFLP）检测85例2型糖尿病患者（其中39例伴糖尿病肾病）及57例正常对照组MTHFR C677T基因型,采用高效液相色谱法测定血浆同型半胱酸水平。结果：糖尿病肾病组MTHFR基因TT纯合基因型,CT杂合基因型及T等位基因频率（分别为38．21％,51．28％,53．85％）均明显高于糖尿病不伴肾病组（分别为19．57％,28．26％,33．70％）及正常对照组（分别为17．54％,28．07％,31．58）,基因型和等位基因频率分布差异均有统计学意义（P＜0．05）,而MTHFR基因该多态性在不伴肾病组与正常对照组之间差异无显著性（P＞0．05）,T等位基因与糖尿病肾病的发生密切相关（OR＝2．30,95％可信区间;1．24－4．26）。糖尿病肾病组,糖尿病不伴肾病组及正常对照组中,MTHFR基因有C677T突变者血浆同型半胱氨酸水平均显著高于无基因突变者。结论：MTHFR基因C677T位碱基突变致血浆同型半胱氨酸水平高是糖尿病肾病发病的重要遗传因素。     

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.     

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.     

2型糖尿病肾病亚甲基四氢叶酸还原酶基因多态性研究

目的探讨亚甲基四氢叶酸还原酶(methylenetetrahydrofolate     

亚甲基四氢叶酸还原酶基因多态性与糖尿病微血管并发症相关性研究

目的：探讨亚甲基四氢叶酸还原酶(MTHFR)基因多态性与中国人2型糖尿病微血管并发症的关系。方法：运用PCR—RFLP检测263例中国人(206例为2型糖尿病，其中148例合并肾病或视网膜病变，57例为正常对照组)MTHFR基因C677T位碱其突变，比较各组间等位基因频率和基因型频率。结果：(1)同时合并肾病和视网膜病变的2型糖尿病组与无微血管并发症的2型糖尿病组及正常对照组相比，TT基因型频率显著增加，突变等位基因T频率也明显升高。(2)2型糖尿病合并肾病组TT基因型频率及T等位基因频率明显高于不伴有肾病的2型糖尿病组及正常对照组。(3)2型糖尿病合并视网膜病组与无视网膜病的2型糖尿病及正常对照组相比，TT基因型频率及T等位基因频率明显升高。结论：MTHFR基因C677T碱基突变是促进中国人2型糖尿病患者并发微血管并发症的危险因子，突变T等位基因是糖尿病微血管并发症的易感基因。     

The association between end-stage diabetic nephropathy and methylenetetrahydrofolate reductase genotype with macroangiopathy in type 2 diabetes mellitus.

The T/T genotype of the methylenetetrahydrofolate reductase C677 T gene polymorphism is associated with elevated homocysteine levels and presumably with increased atherosclerotic risk. We evaluated the interaction between this gene polymorphism and end-stage diabetic nephropathy on the observed prevalence of macroangiopathy in type 2 diabetes mellitus. The methylenetetrahydrofolate reductase 677 C/T genotypes were determined in 174 type 2 diabetic patients: 80 with and 94 without renal failure due to diabetic nephropathy. In the patients with renal failure, the T/T genotype and T allele were significantly associated with macroangiopathy (T/T; 31 % vs. 2 %, P = 0.0001 T allele; 59 % vs. 29 %, P = 0.00014), whereas the associations were not significant in the patients without renal failure. In the multiple logistic regression analysis, age (10 years OR 4.05 [1.79 - 9.31], P < 0.0005) and 677 T allele (6.84 [2.12 - 22.05], P = 0.0013) were significantly associated with macroangiopathy in the patients with renal failure. In conclusion, this study demonstrated that the 677 T/T genotype and T allele of MTHFR were significantly associated with macroangiopathy in type 2 diabetic patients with renal failure. The MTHFR 677 T allele, together with renal dysfunction due to diabetic nephropathy, could be a strong risk factor for atherosclerotic disease.     

No association between MTHFR gene polymorphism and diabetic nephropathy in Japanese type II diabetic patients with proliferative diabetic retinopathy

The development of diabetic nephropathy shows marked variation among individuals. Not only hyperglycemia, but also genetic factors may contribute to the development of diabetic nephropathy. Methylenetetrahydrofolate reductase (MTHFR) is involved in remethylation of homocysteine to methionine. Decreased activity of MTHFR which can result in hyperhomocysteinemia may lead to cerebrovascular disease and coronary artery disease. 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. In the present study, we recruited 173 of Japanese type II diabetic patients with proliferative diabetic retinopathy who would be exposed to long-term hyperglycemia, and examined the contribution of the MTHFR gene polymorphism to the development of diabetic nephropathy as microangiopathy. The frequency of the mutated allele was 43.3% in patients with nephropathy (n = 105) versus 41.9% in those without nephropathy (n = 68). The genotype frequencies were +/+, 16.2%; +/−, 54.3%; −/−, 29.5% in patients with nephropathy versus +/+, 13.2%; +/−, 57.4%; −/−, 29.4% in those without nephropathy (+ indicates the presence of the mutation). The MTHFR genotype and allele frequencies were not significantly different between patients with and without nephropathy. Therefore, we conclude that the MTHFR gene polymorphism is not associated with the development of diabetic nephropathy in Japanese type II diabetic patients.     

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 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.     

MTHFR gene polymorphism is susceptible to diabetic retinopathy but not to diabetic nephropathy in Japanese type 2 diabetic patients

AIMS: Previously, we have proposed that methylenetetrahydrofolate reductase (MTHFR) gene polymorphism (C677T) could be a risk factor for diabetic retinopathy. To support our suggestion, we examined in detail the association of MTHFR polymorphism with diabetic retinopathy and nephropathy in Japanese type 2 diabetic patients. METHODS: Subjects (n=190) were free of cardiovascular diseases and were not on hemodialysis. Retinopathy was assessed according to fundamental differentiation; nephropathy was determined according to urinary albumin level; and MTHFR genotype was determined by polymerase chain reaction-restriction fragment length polymorphism. We also analyzed how hyperglycemia affected these three conditions in 131 patients with glycosylated hemoglobin > or =6.5% and fasting blood sugar > or =110 mg/dl. RESULTS: The frequency of 677T/677T homozygous subjects with retinopathy was higher than the frequencies of the other two genotypes, and a significant difference was observed in the distribution of the genotypes (677C/677C, 41.9%; 677C/677T, 31.1%; 677T/677T, 61.5%; P<.05). The susceptibility of 677T/677T homozygote to retinopathy approached significance [odds ratio (OR)=2.17; 95% confidence interval (95% CI)=0.87-5.42]. However, in the population with hyperglycemia, the 677T/677T homozygote modified the risk for retinopathy (OR=4.30; 95% CI=1.42-13.1), especially the risk for nonproliferative retinopathy. In contrast, the 677T/677T homozygote did not affect the risk for nephropathy (OR=1.17; 95% CI=0.45-3.05), even in subjects with hyperglycemia (OR=1.50; 95% CI=0.50-4.48). CONCLUSIONS: Our results are highly suggestive of an important role for MTHFR genotype in susceptibility to retinopathy under hyperglycemia, but not to nephropathy. Preventive therapies based on MTHFR polymorphism could delay the onset of retinopathy in type 2 diabetic patients.     

MTHFR C677T and A1298C gene polymorphisms and hyperhomocysteinemia as risk factors of diabetic nephropathy in type 2 diabetes patients

Point mutations in methylenetetrahydrofolate reductase (MTHFR) and hyperhomocysteinemia were implicated in the pathogenesis of diabetic nephropathy (DN) in many ethnic groups. This study addressed the association of C677T and A1298C single nucleotide polymorphisms (SNPs) of MTHFR gene with DN in Tunisian type 2 diabetes (T2DM) patients. Study subjects comprised 93 DN patients, 267 patients with normoalbuminuria, and 400 control subjects. C677T and A1298C genotypes were determined by PCR-RFLP analysis, and homocysteine levels were measured by ELISA. A1298C and C677T were highly prevalent among T2DM patients, with allele frequencies of 0.26 and 0.36, respectively. Higher mutant 677T allele and 677C/T and 677T/T genotypes of C677T SNP, but not A1298C SNP, together with 677C/1298A, 677C/1298C, and 677T/1298A haplotypes were seen in DN patients compared to normoalbuminuric patients, (p<0.001). Plasma homocysteine was positively associated with MTHFR 677T/T genotype among the three groups, and was significantly elevated in double heterozygous DN patients but not in normoalbuminuric patients or controls. Logistic regression analysis with DN as dependent variable showed that homocysteine (OR, 1.153) and MTHFR 677T/T (OR, 9.799) were the only variables associated with DN, after adjusting for possible confounding variables. C677T, but not A1298C, SNP, is a risk factor for DN, presumably acting by elevating homocysteine levels.     

Associations of methylenetetrahydrofolate reductase C677T genotype with blood pressure levels in Chinese population with essential hypertension

Objective: To confirm the association between baseline blood pressure (BP) levels and the methylenetetrahydrofolate reductase (MTHFR) C677T gene polymorphism in patients with essential hypertension. Methods: A total of 347 patients were enrolled from the Dongzhi community in Anhui Province, China. The C677T polymorphism of the MTHFR gene was detected using high-throughput TaqMan allelic discrimination assay. Baseline BP was measured using a standardized mercury-gravity monometer. Results: In the whole sample, the frequency of the MTHFR C677T genotypes CC, CT, and TT were 38.6%, 48.1%, and 13.3%, respectively. In a recessive model (CC+CT versus TT genotypes), baseline diastolic blood pressure (DBP) was significantly higher in patients with the TT genotype compared to those with the CT or CC genotypes (P= 0.013). We also divided all patients into three groups based on the tertiles of the baseline BP distribution. Compared to subjects in the lowest tertile of DBP, the adjusted odds of having the TT genotype among subjects in the highest tertile was 2.6 (95% CI: 1.1 to 6.2). However, no significant associations were observed between baseline systolic blood pressure (SBP) and the MTHFR C677T polymorphism. Conclusions: The MTHFR gene polymorphism could be an important genetic determinant of baseline DBP levels in Chinese essential hypertensive patients.     

MTHFR基因多态性与冠心病的关系

目的研究天津地区人群N^5,N^10-亚甲基四氢叶酸还原酶（MTHFR）基因C677T多态性与冠心病的关系。方法应用聚合酶链反应（PCR）技术和限制性酶切片段长度多态性（RFLP）分析技术检测50例冠心病患者（冠心病组）和50例正常人（对照组）的MTHFR基因C677T多态性,应用高效液相色谱法测定血浆同型半胱氨酸（Hcy）水平,采用125I标记放免法测定血清叶酸浓度。结果1.冠心病组与对照组MTHFR基因频率分布不同（P〈0.05）,对照组CC型、TC型、TT型基因频率分别为52.0%,28.0%,20.0%,冠心病组分别为26.0%,44.0%,30.0%。冠心病组T等位基因频率为52.0%,C等位基因频率为48.0%,与对照组比较有显著性差异（P〈0.05）。2.两组的TT基因型者血浆Hcy浓度均明显高于CC和TC基因型者（P〈0.05）,而后两者间无显著性差异（P〉0.05）。3.冠心病组Hcy浓度高于照组（P〈0.05）,两组叶酸水平无显著性差异（P〉0.05）,血浆Hcy浓度与叶酸水平呈显著负相关（r分别为-0.617和-0.588,P〈0.05）。结论MTHFR基因C677T点突变与冠心病发病密切相关,MTHFR基因纯合突变是引起高Hcy血症的一个重要的遗传因素。     

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。     

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.     

Association between plasma homocysteine concentrations and asymptomatic cerebral infarction or leukoaraiosis in elderly diabetic patients

Background: The purpose of the present study was to investigate the possible contribution of plasma homocysteine to asymptomatic cerebral infarction (CI) or leukoaraiosis. Methods: The relationship between plasma homocysteine concentrations and cerebral lesions was investigated in 233 elderly diabetic patients (mean age: 74 years) who were divided into three groups based on the neurological and brain MR findings: asymptomatic cerebral infarction (CI), symptomatic CI, and a control group with no evidence of cerebrovascular disease. Plasma total homocysteine concentrations were measured by high‐performance liquid chromatography. The C677T polymorphism in the methylene tetrahydrofolate reductase (MTHFR) gene was assessed by PCR‐RFLP. The total score of T2 high‐intensity lesions on the brain MR images was summed from the focal T2 high‐intensity scores in 24 areas of the brain. Results: Diabetic patients with asymptomatic or symptomatic CI had significantly higher homocysteine concentrations in plasma than the control group. The plasma homocysteine concentration was more strongly associated with the presence and number of small infarctions or infarction of the putamen, which may explain the association between increased plasma homocysteine concentrations and asymptomatic CI in elderly diabetic patients. In the diabetic patients, high plasma homocysteine concentrations were also significantly associated with high scores of total T2 high‐intensity lesions or focal T2 high‐intensity scores in some periventricular regions. Although there was no significant relationship between the MTHFR TT genotype and CI, a significant association was found between the MTHFR TT genotype and total T2 high‐intensity scores. Conclusion: An elevated plasma homocysteine concentration is independently associated with asymptomatic CI and T2 high‐intensity lesions on brain MR images in elderly patients with diabetes mellitus. The association between the MTHFR TT genotype and periventricular T2 high‐intensity lesions, but not with CI, suggests an important effect of C677T MTHFR gene mutation on leukoaraiosis, independent of hyperhomocysteinemia in elderly diabetic patients.     

Methotrexate-induced mucositis in acute leukemia patients is not associated with the MTHFR 677T allele in Mexico

Methylenetetrahydrofolate reductase (MTHFR) has two common variants with reduced activity due to polymorphisms at nucleotides 677 and 1298. Both affect folate metabolism and thus remethylation of homocysteine, but are also thought to affect nucleotide synthesis and DNA methylation. Methotrexate (MTX), which interrupts folate metabolism, is used in the treatment of a variety of diseases including acute lymphoblastic leukemia (ALL), but exerts in some patients toxic effects on fast dividing tissues such as mucosal epithelia. The enhanced toxicity may be due to cooperative effects between MTX and MTHFR variants. Accordingly, it has been reported that carrying the 677T allele of the MTHFR is a risk factor for MTX-associated mucositis. As in the Mexican population, which is characterized by a high prevalence of the 677T MTHFR variant, several of its commonly associated defects have not been observed, we investigated the relationship between MTX toxicity and the 677T allele. Out of 28 patients with ALL (CC: 2, CT: 10, TT: 16), 16 had episodes of MTX-associated mucositis (CC: 0, CT: 6, TT: 10). Neither at the gene level nor at the genotype level was a significant association with mucositis found. It may be postulated that the risk of higher MTX toxicity in patients with decreased MTHFR activity could be neutralized by the normally folate rich diet in Mexico.     

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.     

亚甲基四氢叶酸还原酶基因C677T多态性与原发性高血压患者动脉顺应性的关系

目的研究亚甲基四氢叶酸还原酶基因C677T多态性与原发性高血压及动脉顺应性的关系。方法对695例原发性高血压患者和509例年龄匹配的正常对照者采用聚合酶链反应和限制片长多态性分析方法进行基因多态性分析,电泳判断基因型及测序,并测定颈动脉—桡动脉脉搏波速度和颈动脉—股动脉脉搏波速度。结果高血压组TT基因型频率和T等位基因频率显著高于正常对照组(26.5%比20.6%及48.7%比42.4%,P=0.015和0.002)。T等位基因携带者的颈动脉—股动脉脉搏波速度显著高于CC基因型者(P<0.05),高血压组颈动脉—桡动脉脉搏波速度在T等位基因携带者也显著高于CC基因型者(P=0.001)。携带T等位基因的高血压患者颈动脉—股动脉脉搏波速度及非单纯收缩期高血压患者颈动脉—桡动脉脉搏波速度均显著高于CC基因型者(P<0.05)。结论亚甲基四氢叶酸还原酶基因C677T多态性可能与原发性高血压发病危险性增加有关,并且677T等位基因可能是高血压动脉硬化的遗传因素。     

The 5,10-methylenetetrahydrofolate reductase C677T polymorphism interacts with smoking to increase homocysteine

Elevated homocysteine is a risk marker for several human pathologies. Risk factors for elevated homocysteine include low folate and homozygosity for the T allele of the 5,10-methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism. Because nitric oxide may inhibit folate catabolism and endothelial nitric oxide synthase activity is reduced in smokers, we postulated that smoking status might modify the impact of the MTHFR C677T polymorphism on homocysteine (tHcy) concentrations. We tested this hypothesis in a healthy young adult population for which MTHFR C677T genotypes and tHcy concentrations were previously reported. The MTHFR 677TT genotype was significantly associated with elevated tHcy concentrations in smokers (P = 0.001) but not in non-smokers (P = 0.36). Among smokers, the MTHFR 677TT genotype was significantly associated with high tHcy in heavy smokers (P = 0.003) but not light smokers (P = 0.09), in men (P = 0.003) but not women (P = 0.11), and in subjects from the lowest serum folate quartile (P = 0.49) but not from folate quartiles 2-4 (P = 0.49). After adjustment for nutritional variables, interactions between MTHFR C677T genotype and NOS3 G894T genotype, and between MTHFR genotype, smoking status and gender were statistically significant. We propose that hyperhomocysteinemia in MTHFR 677TT homozygote smokers is the consequence of mild intracellular folate deficiency caused by a smoking-related reduction of NOS3 activity that is exacerbated when serum folate is low.