亚甲基四氢叶酸还原酶基因多态性与结直肠癌易感性的关系

目的:研究亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)基因C677T、A1298C多态性与结直肠癌易感性的关系。方法:在江苏省进行了一个病例-对照研究(结直肠癌患者315例,人群对照371例),调查研究对象的生活习惯,抽取静脉血,提取白细胞DNA,采用PCR-RFLP检测研究对象的MTHFR C677T、A1298C基因型。结果:1)男女合计的结直肠癌组、结肠癌组和直肠癌组与对照组之间的MTHFR C677T、A1298C基因型分布频度和等位基因频度差异无统计学意义,MTHFR C677T、A1298C基因多态与结直肠癌、结肠癌和直肠癌的易感性无显著相关。2)在男性中,结肠癌组MTHFR C677T T/T基因型的频度为24.6%,明显高于对照组的14.8%,但差异无统计学意义,χ2=3.42,P=0.064。与C677T C等位基因携带者相比,T/T基因型者发生结肠癌的危险性显著升高,其性别、年龄、居住地区及吸烟、饮酒和饮茶习惯调整后的OR为2.15(95%CI:1.07~4.33)。与同时携带MTHFR C677T C等位基因和A1298C A/A基因型者相比,男性的MTHFR C677T T/T和A1298C A/A基因型携带者发生结肠癌的危险性显著升高,其调整OR为2.64(95%CI:1.20~5.81),而他们发生直肠癌的危险性则明显降低,(调整OR=0.47,95%CI:0.22~1.03)。结论:MTHFR C677T基因多态可以影响男性结、直肠癌的易感性,MTHFR A1298C多态与C677T多态在对男性结、直肠癌易感性的影响中有协同作用。     

亚甲基四氢叶酸还原酶基因多态性与结直肠癌易感性的关系

目的：研究亚甲基四氢叶酸还原酶（methylenetetrahydrofolate reductase,MTHFR）基因C677T、A1298C多态性与结直肠癌易感性的关系.方法：在江苏省进行了一个病例-对照研究（结直肠癌患者315例,人群对照371例）,调查研究对象的生活习惯,抽取静脉血,提取白细胞DNA,采用PCR-RFLP检测研究对象的MTHFR C677T、A1298C基因型.结果：1）男女合计的结直肠癌组、结肠癌组和直肠癌组与对照组之间的MTHFR C677T、A1298C基因型分布频度和等位基因频度差异无统计学意义,MTHFR C677T、A1298C基因多态与结直肠癌、结肠癌和直肠癌的易感性无显著相关.2）在男性中,结肠癌组MTHFR C677T T/T基因型的频度为24.6%,明显高于对照组的14.8%,但差异无统计学意义,X2=3.42,P=0.064.与C677T C等位基因携带者相比,T/T基因型者发生结肠癌的危险性显著升高,其性别、年龄、居住地区及吸烟、饮酒和饮茶习惯调整后的OR为2.15（95%CI：1.07～4.33）.与同时携带MTHFR C677T C等位基因和A1298C A/A基因型者相比,男性的MTHFR C677T T/T和A1298C A/A基因型携带者发生结肠癌的危险性显著升高,其调整OR为2.64（95%CI：1.20～5.81）,而他们发生直肠癌的危险性则明显降低,（调整OR=0.47,95%CI：0.22～1.03）.结论：MTHFR C677T基因多态可以影响男性结、直肠癌的易感性,MTHFR A1298C多态与C677T多态在对男性结、直肠癌易感性的影响中有协同作用.     

亚甲基四氢叶酸还原酶基因单核苷酸多态与乳腺癌风险

目的 内研究亚甲基四氢叶酸还原酶(MTHFR)基因单核苷酸多态与女性乳腺癌风险的关系。方法 以聚合酶链反应(PCR)和限制性片段长度多态性(RFLF)分析方法,检测了217例乳腺癌患者和218例配对的正常对照者MTHFR因C677T和A1298C基因型,并比较不同基因型与乳腺癌风险的关系。结果 677TT基因型频率在乳腺癌患者和正常对照中的分布差异有显著性(32．7％比24．8％,P=0．02)。携带MTHFR 677TT基因犁者与携带MTHFR 677CC基因型者比较,前者罹患乳腺癌的风险增加1,84倍(95％ C：1．09～3．14)。MTHFR 677CT基因型以及MTHFR A1298C多态与乳腺癌风险不相关。结论 MTHFR基因677C→T突变是女性乳腺癌的遗传易感因素。     

亚甲基四氢叶酸还原酶多态性与乳腺癌化疗敏感性的相关研究

目的:观察叶酸代谢的关键酶亚甲基四氢叶酸还原酶(MTHFR)基因C677T、A1298C多态性与乳腺癌FEC方案化疗敏感性的关系。方法:收集经病理学确诊的初治乳腺癌患者104例,所有病例化疗前抽静脉血,提取DNA,用PCR-RFLP技术检测MTHFR基因型,所有患者行FEC方案新辅助或姑息性化疗2~6周期,比较疗效和基因型之间的关系。结果:104例乳腺癌患者中,MTHFR C677T T/T基因型39例(37.5%)、C/C基因型55例(52.9%)、C/T基因型 10例(9.6%);T/T基因型化疗有效率79.5%(31/39)高于C/C基因型52.7%(29/55)和C/T基因型20.0%(2/10)（P＜0.05）。MTHFR A1298C A/A基因型41例(39.4%),A/C基因型56例(53.8%),C/C基因型7例(6.7%);各基因型化疗有效率之间无统计学关系（P＞0.05）。结论:本研究初步显示MTHFR C677T基因多态性对预测乳腺癌化疗效果具有较好的临床应用价值。     

亚甲基四氢叶酸还原酶基因多态性与中国人群食管癌易感性的Meta分析

目的运用Meta分析的方法综合评价中国人群中亚甲基四氢叶酸还原酶（MTHFR）基因多态性与食管癌发病的相关性。方法通过计算机文献检索中国生物医学文献数据库(CBM) 和PubMed数据库,并结合文献追溯、网上查询(www.baidu.com; www.google.cn)的方法,收集所有关于MTHFR基因多态性与食管癌易感性的病例对照研究或队列研究。以食管癌组与对照组人群基因型分布的OR值为效应指标,各资料间进行一致性检验,以确定采用固定或随机效应模型进行合并分析。发表偏倚用漏斗图和Egger’s线性回归检验来评估。结果共有在国内外发表的相关文献10篇纳入分析,Meta分析结果表明：MTHFR C677T基因多态和MTHFR A1298C基因多态合并OR值及其95%CI分别为1.97（1.69,2.30）,0.84(0.66,1.08)。按是否吸烟进行分层发现吸烟组中MTHFR 677CT/TT基因型与食管癌有关(OR=2.57,95%CI:1.73~3.80),而不吸烟组中未见MTHFR 677CT/TT基因型与食管癌存在关联（OR=1.33,95%CI:0.94~1.88)。结论中国人群MTHFR C677T基因多态性与食管癌易感性有关,MTHFR A1298C基因多态性与食管癌易感性无统计学关联。吸烟可能会增加MTHFR C677T基因型个体患食管癌的危险性。     

亚甲基四氢叶酸还原酶基因多态性与非小细胞肺癌化疗敏感性的关系

背景与目的 亚甲基四氢叶酸还原酶（MTHFR）是叶酸代谢的关键酶，在DNA甲基化中起重要作用。体外研究已经证明一些基因的异常甲基化可以影响肿瘤细胞对细胞毒性药物和干扰DNA合成药物的敏感性。本研究旨在观察MTHFR基因C677T、A1298C多态与非小细胞肺癌（NSCLC）患者对铂类药物为基础的化疗方案敏感性的关系。方法 收集经病理学确诊的中、晚期NSCLC病例97例。用PCR—RFLP技术检测患者MTHFR基因型。所有患者均经以铂类为基础的化疗方案治疗。结果 ①97例NSCLC病例中，MTHFRC677TC／C、C／T和T／T基因型频度分别为34．0％、50．5％和15．5％，A1298CA／A、A／C和C／C基因型频度分别为64．6％、29．2％和6．2％。化疗后总有效率（完全缓解＋部分缓解）为39．2％。②分别分析MTHFRC677T多态性和A1298C多态性与化疗疗效的关系时，未发现这两个多态与NSCLC化疗的疗效有明显关系。而联合分析MTHFRC677T多态性A1298C多态基因型与化疗疗效的关系时，发现携带MTHFRC677TT等位基因（C／T或T／T基因型）、同时携带A1298CA／A基因型者的有效率为51．1％，显著高于同时携带C677TC／T基因型及A1298CC等位基因者（12．5％）（P=0．007，OR=7．30，95％CI：1．34～52．47）。结论 MTHFR基因C677T和A1298C多态联合作用可影响NSCLC对化疗的敏感性，MTHFR基因型检测对指导NSCLC的化疗、预测疗效具有较高的临床价值。     

MTHFR基因多态性与乳腺癌内分泌治疗药物引发子宫内膜病变的相关性分析

目的 探讨MTHFR基因多态性与乳腺癌内分泌治疗药物引发子宫内膜病变的相关性。方法 选取乳腺癌患者80例。采集血液对MTHFR基因C677T、A1298C位点进行测序,比较各基因亚型与子宫内膜厚度、阴道诊刮比例之间的相关性。结果 MTHFR基因CT677T位点各基因型患者间子宫内膜厚度的差异显著,具有统计学意义(P<0.05),对于CT677T,在T显性模式下,即C/T、T/T基因型患者子宫内膜厚度均大于C/C基因型患者,C/T基因型子宫内膜厚度大于C/C基因型(P<0.05)。MTHFR基因A1298C位点各基因型患者间子宫内膜厚度的差异,无统计学意义(P>0.05)。MTHFR基因CT677T位点各基因型患者间子宫内膜诊刮比例差异有统计学意义(P<0.05),其中,C/T基因型患者子宫内膜诊刮率高于A/A及C/C基因型(P<0.05)。同一基因型型患者不同药物组间子宫内膜厚度差异无统计学意义(P>0.05),对于CT677T,C/T基因患者的子宫内膜厚度比C/C和T/T型厚(P<0.05)。结论 内分泌治疗药物相关子宫内膜病变的发生可能与M...     

MTHFR基因多态和饮酒习惯与结直肠癌易感相关性的研究

目的:探讨亚甲基四氢叶酸还原酶(MTHFR)与结直肠癌(CRC)风险的关系。方法:进行了以医院为基础的结直肠癌病例对照研究(结直肠癌新发病例300例,对照300例)。对叶酸代谢相关基因MTHFRC677T和A1298C多态性进行了检测,并与结直肠癌风险关联进行了分析。结果:未观察到MTH-FR677和1298多态单独对CRC发生的影响,但发现MTHFR-677CT/1298AC组合型发生结直肠癌的风险增加,OR值为2.32(95%CI,1.10～4.92,P=0.027)。未发现MTHFR单倍型和双体型基因与CRC的风险之间存在统计学的显著关联。MTHFRC677T和A1298C基因与吸烟程度之间存在交互作用(似然比检验,P=0.002,P=0.001),在吸烟<16包年者中,MTHFR-677T等位基因患结直肠癌的风险增加2.09(95%CI,1.07～4.04),而在吸烟≥16包年者中,MTHFR-1298AA基因型患结直肠癌的风险明显下降,OR值为0.37(95%CI,0.17～0.80)。MTHFRC677T多态与饮酒之间存在交互作用(似然比检验,P=0.000)。结论:MTHFR-677CT/1298AC组合型基因是CRC的危险因素,MTHFR与吸烟、饮酒之间存在一定的交互作用。     

东北地区亚甲基四氢叶酸还原酶基因C677T单核苷酸多态性与乳腺癌易感性的相关性研究

目的::研究亚甲基四氢叶酸还原酶(MTHFR)基因单核苷酸多态性与乳腺癌易感性的关系.方法:采用以人群为基础的病例对照研究方法,聚合酶链反应-限制性片段长度多态性法检测MTHFR基因型在东北地区乳腺癌患者和正常人群中的分布.结果:MTHFR基因677位点在乳腺癌组和对照组中等位基因频率及基因型分布有显著差异性(P<0.05).进一步分析表明,纯合突变G/G基因型、杂合突变C/G基因型与野生C/C基因型相比,患乳腺癌的危险度分别提高了2.23倍和2.00倍.结论:MTHFR基因C677T突变基因型与乳腺癌的易感性有关.     

MTHFR多态性对晚期胃癌患者化疗作用的预测研究

目的:研究亚甲基四氢叶酸还原酶(MTHFR)基因C677T、A1298C多态与胃癌患者对5-FU为基础的化疗敏感性和毒性的关系。方法:晚期胃癌患者106例,用聚合酶链反应-限定性片段长度多态性(PCR-RFLP)技术检测白细胞DNAMTH-FR基因型。所有患者经5-FU为基础的化疗方案治疗。结果:1)在106例晚期胃癌患者中,MTHFRC677TCC、CT、TT基因型分别占31·1%、46·2%和22·6%;MTH-FRA1298CAA、AC、CC基因型者分别为69·8%、29·2%和0·9%;化疗总有效率35·8%。2)MTHFRC677TTT基因型携带者化疗有效率(83·3%)明显高于C677TCT(24·5%;P=0·000)和C677TCC(18·2%;P=0·000)。而MTHFRA1298CAA组有效率(43·2%)亦明显高于A1298CAC CC组(18·8%,P=0·009)。3)在CFL、CFH、LFP方案治疗的患者中,C677T变异子携带者对化疗敏感性更高。对A1298C多态性,患者接受CFL方案化疗时,1298AA纯合子携带者有效率高于1298CT/CC患者。4)MTHFRC677TTT、CT或A1298CAA多态性携带者化疗相关的恶心/呕吐发生率明显高于其他三种多态性者。结论:MTHFR基因多态性的检测可能是晚期胃癌患者接受5-FU为基础化疗疗效和毒副反应的良好预测指标。     

Methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms and the risk of primary Hepatocellular Carcinoma (HCC) in a Chinese population

Objectives Methylenetetrahydrofolate reductase (MTHFR), which is expressed in the liver, may be involved in both DNA methylation and DNA synthesis. It is also indicated as a potential risk factor of liver cancer in patients with chronic liver disease. To date, no study has been conducted on MTHFR and hepatocellular carcinoma (HCC) using a population-based design. The objective of this study was to evaluate the effects of polymorphisms of the MTHFR gene on the risk of primary liver cancer and their possible effect modifications on various environmental risk factors. Methods A population-based case–control study was conducted in Taixing, China. MTHFR C677T and A1298C were assayed by PCR-RFLP techniques. Results The frequency of MTHFR 677 C/C wild homozygotes genotype was 25.8% in cases, which was lower than that in controls (34.5%). The adjusted odds ratios (ORs) for the MTHFR 677 C/T and T/T genotype were 1.66(95% CI: 1.06–2.61), 1.21(95% CI: 0.65–2.28) respectively when compared with the MTHFR 677 C/C genotype. Subjects carrying any T genotype have the increased risk of 1.55(95% CI: 1.01–2.40) for development of primary hepatocellular carcinoma. A high degree of linkage disequilibrium was observed between the C677T and A1298C polymorphisms, with the D′ of 0.887 and p < 0.01. The MTHFR 677 any T genotype was suggested to have potentially more than multiplicative interactions with raw water drinking with p-value for adjusted interaction of 0.03. Conclusion We observed that the MTHFR 677 C/T genotype was associated with an increased risk of primary liver cancer in a Chinese population. The polymorphism of MTHFR 677 might modify the effects of raw water drinking on the risk of primary hepatocellular carcinoma.     

Polymorphisms in the MTHFR gene are associated with breast cancer.

The methylenetetrahydrofolate reductase (MTHFR) gene is a polymorphic gene involved in folate metabolism, DNA biosynthesis, methylation and genomic integrity in actively dividing cells. The MTHFR C677T and A1298C polymorphisms are likely to play an important role in the susceptibility to breast cancer. In this case-control study, we examined the role of MTHFR C677T and A1298C polymorphisms in breast cancer patients. We genotyped 118 premenopausal women with sporadic breast cancer and 193 controls, using a PCR-RFLP method. The allele frequencies of the MTHFR 677T were 31.36% in the breast cancer cases and 28.76% in the controls. The allele frequencies of the MTHFR 1298C were 37.29% in the breast cancer subjects and 31.35% in the controls. Frequencies of MTHFR C677C, C677T and T677T were 50.8, 33.9 and 14.4% in the breast cancer patients and 48.7, 45.1 and 6.2% in the controls, respectively. The results of a chi(2) analysis indicated that the MTHFR 677T allele was significantly distributed (chi(2) = 7.234; p = 0.027). Likewise, the MTHFR T677T genotype showed a 2.5-fold increased risk for breast cancer and the C1298C genotype showed a 1.9-fold increased risk for breast cancer. In the compound genotypes, T677T/A1298A and C677C/C1298C showed a 4.472- and a 2.301-fold increased risk for breast cancer (OR = 4.472, p = 0.001, and OR = 2.301, p = 0.024), respectively. In conclusion, our data suggest that the MTHFR 677T, 1298C alleles, T677T, C1298C genotypes, and C677C/C1298C and T677T/A1298A compound genotypes are genetic risk factors for premenopausal women with sporadic breast cancer.     

MTHFR C677T and A1298C polymorphisms: diet, estrogen, and risk of colon cancer.

5,10-methylenetetrahydrofolate reductase (MTHFR) is a key enzyme in folate metabolism, diverting metabolites toward methylation reactions or nucleotide synthesis. Using data from an incident case-control study (1608 cases and 1972 controls) we investigated two polymorphisms in the MTHFR gene, C677T and A1298C, and their associations with risk of colon cancer. All of the combined genotypes were evaluated separately, and the 1298AA/677CC (wild-type/wild-type) group was considered the reference group. Among both men and women, the 677TT/1298AA (variant/wild-type) genotype was associated with a small reduction in risk [men: odds ratio (OR), 0.7, 95% confidence interval (CI), 0.5-1.0; women: OR, 0.8, 95% CI, 0.5-1.2]. However, the 677CC/1298CC (wild-type/variant) genotype was associated with a statistically significant lower risk among women (OR, 0.6; 95% CI, 0.4-0.9) but not men. When the polymorphisms were considered individually, for A1298C a significant risk reduction associated with the homozygous variant CC genotype was seen among women only (OR, 0.6; 95% CI, 0.5-0.9), and nonstatistically significant reduced risks were observed for the variant 677 TT genotypes among both men and women. Stratification by nutrient intakes showed inverse associations with higher intakes of folate, vitamin B(2), B(6), B(12), and methionine among women with the MTHFR 677CC/1298AA genotypes, but not those with 677TT/1298AA. We observed opposite risk trends for both MTHFR variants, depending on whether women used hormone-replacement therapy or not (P for interaction = <.01). In summary, this study supports recent findings that the MTHFR A1298C polymorphism may be a predictor of colon cancer risk and have functional relevance. The possible interaction with hormone-replacement therapy warrants additional investigation.     

Significant association of methylenetetrahydrofolate reductase single nucleotide polymorphisms with prostate cancer susceptibility in taiwan

Prostate cancer is the most common cause of cancer death in men and is a major health problem worldwide. Methylene tetrahydrofolate reductase (MTHFR) plays an important role in folate metabolism and is also an important source of DNA methylation and DNA synthesis (nucleotide synthesis). To assess the association and interaction of genotypic polymorphisms in MTHFR and lifestyle factors with prostate cancer in Taiwan, we investigated two well-known polymorphic variants of MTHFR, C677T (rs1801133) and A1298C (rs1801131), analyzed the association of specific genotypes with prostate cancer susceptibility, and discussed their joint effects with individual habits on prostate cancer risk. In total, 218 patients with prostate cancer and 436 healthy controls recruited from the China Medical Hospital in central Taiwan were genotyped for these polymorphisms with prostate cancer susceptibility. We found the MTHFR C677T but not the A1298C genotype was differently distributed between the prostate cancer and control groups. The T allele of MTHFR C677T conferred a significantly (p=0.0011) decreased risk of prostate cancer. As for the A1298C polymorphism, there was no difference in distribution between the prostate cancer and control groups. Gene interactions with smoking were significant for MTHFR C677T polymorphism. The MTHFR C677T CT and TT genotypes in association with smoking conferred a decreased risk of 0.501 (95% confidence interval=0.344-0.731) for prostate cancer. Our results provide the first evidence that the C allele of MTHFR C677T may be associated with the development of prostate cancer and may be a novel useful marker for primary prevention and anticancer intervention.     

The Methylenetetrahydrofolate Reductase C677T Polymorphism Influences Risk of Esophageal Cancer in Chinese

Methylenetetrahydrofolate reductase (MTHFR) plays a central role in folate metabolism. This study with381 esophageal cancer patients and 432 healthy controls was conducted to examine the association of MTHFRC677T and A1298C polymorphisms with susceptibility to esophageal cancer (EC) in a Chinese population.Compared with the CC genotype of MTHFR C677T, subjects carrying homozygote TT and variant genotypes(CT+TT) demonstrated reduced risk of EC with adjusted ORs (95% CI) of 0.44 (0.28-0.71) and 0.57 (0.37-0.88),respectively. However, no association was found between the MTHFR A1298C polymorphism and the risk ofEC. Comparing to haplotype CA, haplotypes TA and TC could reduce the susceptibility to EC with adjustedORs (95% CI) of 0.61(0.47-0.79) and 0.06 (0.01-0.43), respectively. In conclusion, the present study suggestedthat the MTHFR C677T polymorphism can markedly influence the risk of EC in Chinese.     

Sex differences in risk of lung cancer associated with methylene-tetrahydrofolate reductase polymorphisms.

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the metabolism of folate and nucleotides needed for DNA synthesis and repair. Variations in MTHFR functions likely play roles in the etiology of lung cancer. The MTHFR gene has three nonsynonymous single nucleotide polymorphisms (i.e., C677T, A1298C, and G1793A) that have a minor allele frequency of >5%. We investigated the associations between the frequencies of MTHFR variant genotypes and risk of lung cancer in a hospital-based case-control study of 1,051 lung cancer patients and 1,141 cancer-free controls in a non-Hispanic White population. We found that compared with the MTHFR 1298AA genotype, the 1298CC genotype was associated with a significantly increased risk of lung cancer in women [(odds ratio (OR), 2.09; 95% confidence interval (95% CI), 1.32-3.29)] but not in men (OR, 0.95; 95% CI, 0.62-1.45). The MTHFR 677TT genotype was associated with a significantly decreased risk of lung cancer in women (OR, 0.60; 95% CI, 0.40-0.92) but not in men. No association was found between the MTHFR G1793A polymorphism and risk of lung cancer. Further analysis suggested evidence of gene-dietary interactions between the MTHFR C677T polymorphism and dietary intake of vitamin B6, vitamin B12, and methionine in women and evidence of gene-environment interactions between the MTHFR C677T and A1298C polymorphisms and tobacco smoking in men. In conclusion, the polymorphisms of MTHFR may contribute to the risk of lung cancer in non-Hispanic Whites and modify the risk associated with the dietary and environmental exposure in a sex-specific manner.     

Genetic susceptibility of methylenetetrahydrofolate reductase (MTHFR) gene C677T, A1298C, and G1793A polymorphisms with risk for bladder transitional cell carcinoma in men

We performed a case-control study of 158 bladder transitional cell carcinoma (TCC) cases and 316 controls to investigate the association between methylenetetrahydrofolate reductase (MTHFR) C677T, A1298G, and G1793A polymorphisms and bladder cancer susceptibility by polymerase chain reaction restriction fragment length polymorphism (PCR-RLFP) technique. The controls were frequency-matched to the cases by age (± 5 years), ethnicity, and smoking status. We also measured serum levels of total homocysteine (tHcy), folate, and vitamin B12. It was found that the 1298AC (odds ratio, OR = 3.74; 95% confidence interval, CI = 2.34-5.47; P = 0.001) and 1298CC (OR = 3.46, 95% CI = 2.37-5.52; P = 0.001) genotypes of MTHFR A1298C were significantly associated with increased risk of bladder TCC. The MTHFR C677T and G1793A polymorphisms were not associated with bladder TCC. After stratification for grade and stage, we observed that the 677TT (OR = 4.47, 95% CI = 2.74-6.72; P = 0.001) and MTHFR 1298CC (OR = 4.78, 95% CI = 2.82-6.89; P = 0.001) genotypes of MTHFR were associated with increased risk of muscle-invasive bladder TCC. We also found that the MTHFR 677CT+1298AA genotypes were associated with an approximately 70% reduction in risk of bladder cancer (OR = 0.31; 95% CI = 0.15-0.68) compared to the combined referent genotype. There were 8 haplotypes and 16 haplotype genotypes based on these three variants. When we used the haplotypes and assumed that the 677T, 1298C, and 1793G alleles were risk alleles, the adjusted odds ratios increased as the number of risk alleles increased: 1.00 for 0-1 variant, 1.88 (1.4-2.7) for any two risk alleles and 2.07 (1.6-2.8) for any three risk alleles. Serum tHcy levels were significantly higher in carriers of the 677T, 1298C, and 1793G alleles compared to noncarriers (all P < 0.01). There was no significant correlation between serum levels of tHcy and folate and bladder cancer risk. Further studies in larger samples size and different ethnicity are required to confirm our findings.     

Methylenetetrahydrofolate reductase (MTHFR) genotype, smoking habit, metastasis and oral cancer in Taiwan

The aim of this study was to evaluate the association and interaction of genotypic polymorphism in methylenetetrahydrofolate reductase (MTHFR) with smoking habits and oral cancer in Taiwan. Two well-known polymorphic variants of MTHFR, C677T (rs1801133) and A1298C (rs1801131), were analyzed in association with oral cancer risk, and their joint effects with individual smoking habits on oral cancer risk are discussed. In total, 620 oral cancer patients and 620 non-cancer controls in central Taiwan were recruited and genotyped. The MTHFR C677T genotype, but not the A1298C, was differently distributed between the oral cancer and control groups. The T allele of MTHFR C677T was significantly more frequently found in controls than in oral cancer patients. Joint effects of smoking and MTHFR C677T genotype significantly affected oral cancer susceptibility. The MTHFR C677T CT and TT genotypes in association with smoking conferred lower odds ratios of 0.66 and 0.54 (95% confidence interval=0.49-0.82 and 0.39-0.86), respectively. Those patients with MTHFR C677T CT and TT genotypes also had a lower risk of oral cancer metastasis. MTHFR C677T genotype may have joint effects with smoking on oral carcinogenesis, and may be a useful biomarker for prediction and prognosis of oral cancer.     

Folate metabolism-related gene polymorphisms and susceptibility to primary liver cancer in North China

Genetic factors may contribute to individual differences in cancer susceptibility. This study was designed to investigate the effects of the polymorphisms of methylenetetrahydrofolate reductase 677 C → T (MTHFR 677 C → T), methylenetetrahydrofolate reductase 1298 A → C (MTHFR 1298A → C), thymidylate synthase (TYMS 3R → 2R), and methionine synthase 2756 A → G (MTR 2756 A → G) on the risk of primary liver cancer (PLC). We conducted a case-control study involving 356 PLC cases and 641 healthy controls in North China. Compared with the MTHFR 677CC genotype, the MTHFR 677TT genotype showed an increased risk for PLC (TT vs. CC: adjusted odds ratio (OR) = 1.56; 95% confidence interval (CI): 1.02-2.40; P = 0.043) after adjusting for gender and age, whereas the MTHFR 1298CC genotype showed a significantly decreased risk for PLC (CC vs. AA: adjusted OR = 0.23; 95% CI: 0.08-0.70; P = 0.010). However, no significant association was found between the TYMS 3R → 2R or the MTR 2756 A → G polymorphism and the risk of PLC. Our results suggest that the MTHFR 677 C → T and the MTHFR 1298A → C genetic polymorphisms might play important role in hepatic carcinogenesis. Further studies with larger sample sizes are required to validate this association.