亚甲基四氢叶酸还原酶基因C677T突变与高尿酸血症的相关性研究

目的探讨高尿酸血症（HUM）与亚甲基四氢叶酸还原酶（MTHFR）基因C677T突变及高血糖、肥胖和高血压等的相关性。方法从青岛地区糖尿病流行病学调查数据库中，随机选取HUM＋T2DM患者79例、HUM无T2DM患者（HUM组）90例、并选取T2DM无HUA患者（DM组）90例和健康对照（NC）91例。采用聚合酶链反应-限制性片段长度多态性技术检测MTHFR基因突变。结果HUM组和HUM＋T2DM组MTHFR677T等位基因频率分别为46．7％和51．3％，TT基因型频率分别为23．3％和26．6％，两组差异无统计学意义（P〉0．05）；T等位基因和TT基因型频率在NC组和DM组间差异无统计学意义（P〉0．05）；而HUM组和HUM＋T2DM组MTHFR677T等位基因型频率和TT基因型频率均分别高于NC组和DM组（P〈0．005）。CT和TT基因型患者平均血尿酸水平（分别为394．2μmol／L和465．8μmol／L）明显高于CC基因型者（347．3μmol／L）（P〈0．05）。多因素logistic回归分析表明，调整BMI、SBP、TG、TC及饮酒等因素后显示，MTHFR基因型是HUM患病的独立危险因素。结论MTHFR基因C677T突变是青岛地区人群发生HUM的独立危险因素。     

高血压患者亚甲基四氢叶酸还原酶基因C677T多态性与血脂异常的相关性

目的探讨血浆同型半胱氨酸(Hcy)及其代谢关键酶亚甲基四氢叶酸还原酶(MTHFR)C677T基因多态性与中国汉族人群原发性高血压患者血脂异常的关系。方法选取原发性高血压患者312例,女性134例,男性178例,平均年龄58.25岁,收集患者基本资料,检测血浆Hcy、血脂、空腹血糖(FBG)、尿酸(UA)等临床生物化学指标。应用Taqman探针技术检测患者MTHFR C677T基因分型。根据2007年中国成人血脂异常防治指南,将入选的312例原发性高血压患者分为血脂异常组194例和血脂正常组118例,同时将血脂异常组分为4个亚组:高胆固醇血症组54例,高甘油三酯血症组53例,混合型高脂血症组59例,低高密度脂蛋白血症组22例,并进行亚组分析。结果血脂异常组体质指数(BMI)、FBG、UA高于血脂正常组(P0.01)。血脂异常组MTHFR C677T的CC、CT、TT三种基因型频率和C、T两种等位基因频率与血脂正常组比较差异无统计学意义(P0.05),血脂异常各亚组之间的基因型频率、等位基因频率差异无统计学意义,与血脂正常组之间差异亦无统计学意义。MTHFR C677T不同基因型间四项血脂水平均无统计学差异,但TT基因型者Hcy水平高于CT、CC基因型者(P0.05),而CT基因型者Hcy水平与CC基因型者比较差异无统计学意义(P0.05)。高密度脂蛋白胆固醇(HDLC)水平与Hcy水平呈负相关(r=-0.116,P0.05),但是在校正了年龄、BMI、UA、FBG后此相关性消失;总胆固醇(TC)、甘油三酯(TG)、低密度脂蛋白胆固醇(LDLC)水平与Hcy水平无相关性(P0.05)。Logistic回归分析显示,在校正了BMI、FBG、UA后基因型与血脂异常无相关性(P0.05)。结论在原发性高血压患者中MTHFR C677T基因多态性与血脂异常无关联,而与Hcy呈显著相关。血脂异常与FBG、UA、BMI有关,而与Hcy无关,但HDLC与血浆Hcy水平呈负相关。     

PCR-RFLP法检测亚甲基四氢叶酸还原酶基因C677T突变

目的 建立一种简便、实用的检测亚甲基四氢叶酸还原酶(MTHFR)等位基因C677T点突变的方法，并初步观察部分健康老人和老年血管性痴呆(VD)患者中MTHFR等位基因C677T点突变情况。方法PCR特异性扩增MTHFR基因序列，扩增产物用限制性内切酶HinfⅠ酶切，经聚丙烯酞胺凝胶电泳(PAGE)分离、溴化乙锭染色后，观察酶切位点的限制性片段长度多态性(RFLP)图谱．共检路标本167例，其中健康老人(≥65岁)138例、老年VD29例，并计算了各基因型频率和等位基因频率。结果 健康老人组和老年VD患者组均检炽到C等位基因野生型(CC)、杂合于(CT)和T等位基因纯合子(TT)基因型，各组MTHFR基因的C677T点突变中T突变位点的频率分别为43．8％、51．7％。结论 该方法简便、实用，适于一般实验室应用及流行病学调查．     

亚甲基四氢叶酸还原酶基因多态性与缺血性卒中

近年来的研究表明,高同型半胱氨酸血症通过多种机制造成血管内皮损伤,破坏机体凝血和纤溶系统,影响脂质代谢,是卒中的独立危险因素.亚甲基四氢叶酸还原酶(MTHFR)是体内同型半胱氨酸代谢途径的关键酶,该酶含量不足或活性下降将直接导致同型半胱氨酸在体内的蓄积,从而引起高同型半胱氨酸血症.虽然许多研究发现MTHFR基因突变是该酶缺乏或活性下降的主要原因,但是MTHFR基因突变与缺血性脑血管病的相关关系目前颇有争议.文章就MTHFR基因多态性与缺血性卒中的关系进行综述.     

甲基四氢叶酸还原酶基因C677T多态性与大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(MTHFR)基因C677T多态性与大肠癌(CRC)遗传易感性的关系.方法 采用聚合酶链反应(PCR)和限制性片段长度多态性(RFLP)分析方法检测120例CRC患者和202例正常对照的MTHFR C677T的基因型分布及差异.结果 与对照组相比,CRC组677T等位基因频率显著降低(OR:0.57,95％ CI:0.40 ～0.81,P=0.002).与CC纯合子相比,TT纯合子的CRC风险显著降低至0.28倍(95％ CI:0.12～0.63,P=0.002) CT杂合子的CRC风险虽降低至0.64倍(95％ CI:0.37～ 1.08,P=0.094),差异无统计学意义.在CRC人群中,MTHFR C677T与肿瘤大小、位置、组织学类型、分化程度、淋巴结转移以及Dukes分期均无显著相关性(P＞0.05).结论 MTHFR 677TT基因型可降低CRC风险;MTHFR C677T基因型与CRC肿瘤特征无相关性.     

亚甲基四氢叶酸还原酶基因C677T多态性与HBV感染后疾病转归的关系

目的:探讨MTHFR C677T多态性对HBV感染后疾病转归的关系. 方法:采用TaqMan SNP基因分型和基因测序的方法检测152例健康对照人群、161例感染HBV后自愈者、173例慢性乙型肝炎患者、138例乙型肝炎肝硬化患者以及181例HBV相关性肝癌患者的MTHFR基因C677T位点的基因型及等位基因的分布及其差异. 结果:805例研究对象的基因型分布为CT基因型占47.09%、TT占30.43%、CC占22.48%;等位基因频率:C为46.02%,T为53.98%,此结果明显不同于以往报道.等位基因和基因型分布在各肝病组无统计学差异.分析不同性别在各组中的分布特征表明,男性患者TT在各组中显示风险降低,特别在肝硬化组TT和CT的OR值最低(与自愈组比较:0.675,95%CI:0.308-1.479;0.510,95%CI:0.248-1.050);而在女性的自愈、慢乙型肝炎和肝硬化组,TT和CT显示风险度增加,特别在肝硬化组OR值最高(与自愈组比较:3.542,95%CI:0.885-14.171;3.167,95%CI:0.821-12.211),具有统计学差异(P=0.022).同时,在女性肝癌组却显示风险度降低(0.638,95%CI:0.213-1.904;0.500,95%CI:0.175-1.432). 结论:本研究显示MTHFR C677T多态性在中国天津汉族人中显示了较高的TT基因型频率,同时提示MTHFR C677T多态性在HBV感染后疾病发展的过程中发挥重要作用.     

亚甲基四氢叶酸还原酶基因多态性与糖尿病肾病研究进展

亚甲基四氢叶酸还原酶(MTHFR)催化5,10-亚甲基四氢叶酸转变为5-亚甲基四氢叶酸,后者作为同型半胱氨酸(Hcy)转变为甲硫氨酸的甲基供体.MTHFR基因突变使该酶存在缺陷,导致Hcy积聚,后者具有血管损伤作用,通过损伤血管内皮细胞、促进血小板聚集、细胞和间质增生及胶原合成等参与糖尿病肾病发展的病理过程.     

冠心病患者亚甲基四氢叶酸还原酶基因多态性87例研究

目的探讨N5,N10-亚甲基四氢叶酸还原酶(MTHFR)基因多态性与冠心病的关系。方法对2003年11月至2005年8月贵阳医学院附属医院及贵州市第二人民医院住院的87例冠心病患者(冠心病组)及同期在门诊进行健康体检的73名健康人(对照组),采用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)法检测其MTHFRC677T基因多态性。结果对照组与冠心病组MTHFR677位T等位基因的分布频率分别是18.5%,36.1%,病例组MTHFR基因C677T的CT基因型及T等位基因频率显著高于对照组,差异有显著性(P<0.05)。结论MTHFRC677T基因多态性与冠心病密切相关。     

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     

胃癌组织中叶酸水平与代谢酶亚甲基四氢叶酸还原酶基因多态性的关系研究

目的探讨人胃癌组织中叶酸水平与代谢酶亚甲基四氢叶酸还原酶(MTHFR)基因多态性的变化及其关系。方法收集38例晚期胃癌患者的癌区、癌旁和外周正常区域组织标本,以自动化学发光系统测定人胃癌组织叶酸含量,PCR-限制性内切酶片段长度多态性技术检测MTHFR基因677(C→T)和1298(A→C)两个常见多态,并以34例慢性浅表性胃炎(CSG)组织作为对照,分析叶酸、MTHFR基因多态性的变化及其关系。结果CSG对照组中叶酸含量[(5.48±2.15)ng/ml]明显高于胃癌组织[癌区(3.65±1.97)ng/ml,癌旁(4.01±2.11)ng/ml,外周正常组织(4.00±2.20)ng/ml],胃癌组织MTHFR基因的两个多态位点中,677CT基因型叶酸含量最高,而1298(A→C)多态则未见明显差异。677TT基因型与CC基因型相比有减少胃癌发生的趋势,但与其生物学行为关系不密切。677TT基因型高叶酸组与CC基因型低叶酸组相比发生胃癌的相对风险度为0.11(95%CI:0.01~1.02)。癌组织标本检测中未发现1298CC基因型。结论组织叶酸含量降低者发生胃癌风险明显增加。MTHFR基因多态性并不是胃癌的一个孤立危险因素,它和组织叶酸含量共同作用于胃癌发生。     

Association of methylenetetrahydrofolate reductase (C677T) polymorphism with hyperuricemia

Background and aimsHomozygosity for the thermolabile variant of 5,10-methylene tetrahydrofolate reductase (C677T) has been suggested to be positively associated with the risk of vascular disease and neural tube defects. In addition, recent studies have suggested that elevated serum uric acid predicts ischemic heart disease, and epidemiological data on ethnic groups have suggested that genetic factors are determinants of serum uric acid levels. In this study, we tested the hypothesis that 5,10-methylenetetrahydrofolate reductase (C677T) polymorphism may be associated with hyperuricemia.Methods and resultsSamples from 518 healthy individuals (268 men and 250 women) were analyzed for MTHFR genotyping and serum uric acid. The participants were categorized to homozygous wild type (CC), heterozygous for wild type and thermolabile (CT), or homozygous for the thermolabile (TT) variant. Serum uric acid was significantly higher in males and females with TT genotype than those with either CC or CT genotype (p = 0.0001, ANOVA). Univariate and multivariate analysis showed that 5,10-methylenetetrahydrofolate reductase (C677T) polymorphism was a strong correlate and predictor of uric acid in males (r = 0.28, p = 0.0001, β = 0.673, p = <0.001) and in females (r = 0.27, p = 0.0001, β = 0.599, p = <0.001). Odds ratio analysis has also shown that the risk of hyperuricemia was greater in males (OR 3.1, CI 1.8–5.2, p = 0.001) and females (OR 3.3, CI 1.9–5.7, p = <0.001) with CT genotypes and in males (OR 3.7, CI 1.3–10.7, p = 0.014) and females (OR 3.2, CI 1.1–9.7, p = 0.032) with TT genotypes than in those with CC genotypes.ConclusionResults from this study suggest that mutation of 5-MTHFR C677T contributes to the higher uric acid levels in both males and females and may be a risk factor for hyperuricemia.     

An updated meta-analysis of methylenetetrahydrofolate reductase gene 677C/T polymorphism with diabetic nephropathy and diabetic retinopathy

Studies investigating the association of methylenetetrahydrofolate reductase (MTHFR) gene 677C/T polymorphism with diabetic nephropathy and diabetic retinopathy have so far reported inconclusive results. We therefore aim to address this inconclusiveness by conducting a meta-analysis. Random-effects model was applied irrespective of between-study heterogeneity. Data and study quality were assessed in duplicate. A total of 7807 and 1599 subjects from 21 and 8 studies were analyzed for diabetic nephropathy and diabetic retinopathy, respectively. Carriers of 677TT genotype were 1.71 (95% confidence interval [95% CI]: 1.02-2.88; P = 0.042) and 2.89 (95% CI: 1.51-5.53; P = 0.001) times more likely to develop diabetic nephropathy separately relative to diabetic patients without nephropathy and nondiabetic controls. Likewise, this association was preserved for diabetic patients with retinopathy referring to those without (odds ratio [OR] = 1.86; 95% CI: 1.21-2.86; P = 0.004). Subgroup analyses showed that ethnicity was a possible confounder, especially in West Asians and Africans, and so were gender and duration of diabetes mellitus in diabetic nephropathy studies. Probability of publication bias was low across all comparisons as reflected by the funnel plot and corresponding test. Taken together, our results demonstrate that MTHFR gene 677TT genotype might confer a moderately augmented risk for diabetic nephropathy and diabetic retinopathy.     

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677C/T多态性与上海地区2型糖尿病合并大血管并发症的关系

目的 研究亚甲基四氢叶酸还原酶（MTHFR）基因677C／T多态性与糖尿病大血管并发症（脑梗死和冠心病）之间的关系。方法 在416例中国人受试者中：大血管病变患者（AS组，即脑梗死亚组和冠心病亚组总和）216例，其中脑梗死亚组（CI）111例，该亚组中伴及不伴糖尿病患者分别为50例及61例；冠心病亚组（CHD）105例，该亚组中伴及不伴糖尿病患者分别为48例及57例。糖尿病无大血管病变者（DM）100例，正常对照（C）100例。研究方法采用PCR／酶解鉴定基因变异及群体关联分析。结果 大血管病变组中MTHFR基因的677C／T的TT基因型和T等位基因频率显著增高。Logistic回归分析表明MTHFR基因参与大血管病变（AS）的致病过程。大血管病变各组内糖尿病和非糖尿病两亚组间相互比较基因型频率差异没有显著性。大血管病变不同亚组按有无糖尿病及性别分层后可见高密度脂蛋白胆固醇及舒张压水平随基因型不同而差异有显著性。结论 在中国人中，不论有无糖尿病，MTHFR基因均参与大血管病变（脑梗死或冠心病）的致病过程。     

亚甲基四氢叶酸还原酶基因677和1298位点多态性与溃疡性结肠炎的相关性

目的 探讨亚甲基四氢叶酸还原酶(MTHFR)基因C677T和A1298C位点多态性与浙江汉族人群溃疡性结肠炎(UC)的关系.方法 采用限制性片段长度多态性PCR(PCR-RELP)法,在274例UC患者和726例正常对照者中检测MTHFR C677T及A1298C基因多态性分布差异.结果 UC患者中,MTHFR C677T突变等位基因(T)和基因型(CT+TT)频率与正常对照组相比差异无统计学意义(P＞0.05);而MTHFR A1298C突变等位基因(C)和基因型(AC+CC)频率均高于正常对照组(35.77%比29.96%,P=0.013;52.19%比44.90%,P=0.039).另外,MTHFR 677纯合子突变基因型(TT)、突变等位基因(T)以及677CT/1298AC复合基因型频率在广泛性结肠炎患者中明显高于远端结肠炎(37.66%比14.72%,P=0.0002;49.35%比32.99%,P=0.0004;29.87%比15.23%,P=0.006);重度UC患者的MTHFR 1298位点突变等位基因(C)频率显著低于(轻+中)度患者(18.97%比33.88%,P=0.022).结论 MTHFR C677T及A1298C基因多态性与浙江汉族UC明显相关.

Abstract：

Objective To investigate the association between the genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) and ulcerative colitis (UC) of Han ethnic population in Zhejiang, China. Methods Two hundred and seventy-four consecutive patients with UC and 726 healthy controls (HC) were studied. The genetic polymorphisms of MTHFR (C677T and A1298C) were genotyped using PCR-RELP methods. Results The frequencies of variant allele and genotype in MTHFR A1298Cgene were higher in UC patients than in the HC (35.77% vs 29. 96%, P =0. 013; 52. 19% vs 44. 90%,P=0.039; respectively). However, there were no significant discrepancies of the allele and genotype frequencies in the MTHFR C677T gene between the UC patients and the HC (P ＞ 0. 05 ). In addition, the MTHFR 677Tr homozygote, T allele and 677CT/1298AC compound genotype were more prevalent in patients with extensive colitis than in those with distal colitis (37. 66% vs 14. 72% ,P = 0. 0002; 49. 35% vs 32.99% ,P =0. 0004; 29. 87% vs 15.23% ,P =0. 006; respectively). Furthermore,the variant allele in the MTHFR A1298C gene (C) in severe UC patients was significantly lower than in mild and moderate UC patients (18.97% vs 33. 88% ,P =0. 022). Conclusion The genetic polymorphisms of MTHFR C677T and A1298C are obviously associated with Han ethnic population with UC in Zhejiang province.     

亚甲基四氢叶酸还原酶基因 C677 T多态性与中国山东地区汉族人群缺血性卒中、高尿酸血症的相关性

目的：探讨亚甲基四氢叶酸还原酶（methylenetetrahydrofolatereductase,MTHFR）基因C677 T 多态性与中国山东地区汉族人群缺血性卒中、高尿酸血症的相关性。方法纳入山东地区汉族急性缺血性卒中患者和年龄、性别相匹配的对照者。采用聚合酶链反应扩增和芯片杂交显色技术检测MTHFR基因C677T 多态性,并测定血清尿酸浓度。结果共纳入山东地区汉族急性缺血性卒中患者145例和年龄、性别相匹配的对照者145名。缺血性卒中组糖尿病构成比（26.90％对6.89％;χ2=20.653,P<0.001）以及空腹血糖[（5.56±1.57）mmol/L对（5.01±1.11）mmol/L;t=－3.390, P=0.001]、高半胱氨酸[中位数,四分位数间距：18.2（16.30~22.55）μmol/L对15.20（12.10~17.85）μmol/L;Z=－6.323,P<0.001]和尿酸[43.0（361.60~490.45）μmol/L对285.9（267.00~346.25）μm o l/L;Z=－10.360, P<0.001]水平均显著高于对照组;缺血性卒中组 T T 基因型（42.07％对15.17％;χ2=25.673, P<0.001）和 T 等位基因（58.28％对34.48％;χ2=33.008, P<0.001）分布频率均显著高于对照组。多变量logistic回归分析显示,尿酸[优势比（ odds ratio, OR）1.018,95％可信区间（confidence interval, CI）1.013~1.024;P<0.001]、TT 基因型（对CT 基因型, OR 6.774,95％CI 1.779~25.507;P=0.005）、高血压（ OR 1.919,95％CI 1.013~3.636;P=0.045）、高半胱氨酸（ OR 1.153,95％CI 1.059~1.258;P=0.001）为缺血性卒中的独立危险因素。将缺血性卒中组与对照组合并,共101例存在高尿酸血症,189例尿酸正常。高尿酸血症组糖尿病患者构成比（32.67％对11.64％;χ2=23.749, P<0.001）以及总胆固醇[（5.67±1.56）mmol/L对（5.10±1.33）mmol/L;t=－3.255,P<0.001]和高半胱氨酸[19.50（17.10~24.70）μmol/L对15.40（12.60~18.05）μmol/L;Z=－7.236,P<0.001]水平显著高于尿酸正常组,TT 基因型（55.45％对13.76％;χ2=56.409,P<0.001）和T等位基因（71.79％对32.54％;χ2=79.561,P<0.001）分布频率显著高于尿酸正常组。多变量logistic回归分析显示,TT 基因型（对CC 基因型,OR 6.434,95％CI 2.334~17.736;P<0.001）、CT 基因型（对CC基因型,OR 2.234,95％CI 1.019~4.898;P=0.045）、高半胱氨酸（OR 1.081,95％CI 1.010~1.157;P=0.024）、总胆固醇（OR 1.363,95％CI 1.123~1.653;P=0.002）为高尿酸血症的独立危险因素。结论 MTHFR基因C677T TT 基因型和血清尿酸水平是中国山东地区汉族人群缺血性卒中的独立危险因素,MTHFR基因C677T TT 基因型亦为该人群高尿酸血症的独立危险因素,调整饮食习惯可能对山东地区汉族人群缺血性卒中的预防具有积极意义。     

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．     

Methylenetetrahydrofolate reductase C677T and A1298C polymorphisms and gastric cancer susceptibility

AIM: To identify the association between methylenetetrahydrofolate reductase (MTHFR) polymorphisms and gastric cancer (GC) susceptibility.METHODS: Systematic searches were performed on the electronic databases PubMed, ISI, Web of knowledge, CNKI and Wanfang, as well as manual searching of the references of the identified articles. A total of 26 papers were included in this meta-analysis. Overall and subgroup analyses were performed. Odds ratio (OR) and 95%CI were used to evaluate the associations between MTHFR polymorphisms and GC risk. The I² statistics were used to evaluate between-study heterogeneity. Sensitivity analysis was also performed.RESULTS: Increased risk was found for the MTHFR C677T polymorphism under four genetic models (TT + CT vs CC: OR = 1.23, P = 0.002; T vs C: OR = 1.15, P = 0.001; TT vs CC: OR = 1.37, P = 0.0005; TT vs CT + CC: OR = 1.17, P = 0.0008). Subgroup analysis by ethnicity suggested that C677T polymorphism conferred a risk of GC in eastern but not in western populations. Stratification by tumor site showed an association between the C677T polymorphism and gastric cardia cancer and non-cardia GC in the worldwide population and in eastern populations. Regardless of comparisons with controls or diffuse-type GC, a positive association was found for the C677T polymorphism and an increased risk of intestinal-type GC in the whole population and in western populations. With regard to the A1298C polymorphism, we found that genotype CC was significantly decreased and conferred protection against GC in eastern populations (CC vs AA: OR = 0.44, P = 0.03; CC vs AC + AA: OR = 0.46, P = 0.04).CONCLUSION: MTHFR C677T polymorphism is a risk factor for GC, and the A1298C polymorphism may be a protective factor against GC in eastern populations.