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。     

汉族脑卒中与N5,N10亚甲基四氢叶酸还原酶基因多态性的相关性研究

目的　探讨人体 N5,N1 0亚甲基四氢叶酸还原酶 (MTHFR)的基因多态性与脑卒中的遗传相关性。方法　采用限制性内切酶片段长度多态性方法 (PCR- RFLP) ,对 67例脑卒中病人和 78例健康人 MTHFR基因 C677T多态性位点进行检测。结果　病例组 MTHFR基因 T、C等位基因频率分别为 53%、47%,对照组为 39.7%、60 .3%,两组显著性差异 (χ2 =5.0 9,P<0 .0 5)。 TT型携带者较 CC型携带者罹患脑卒中的相对风险度为 2 .35(95%CI1 .0 2～ 5.43)。 T等位基因携带者较 C等位基因携带者罹患脑卒中的相对风险度为 1 .71 (95%CI1 .0 7～ 2 .74)。出血性卒中与缺血性卒中之间等位基因及等位基因型频率无明显差异。结论　脑卒中汉族人群 MTHFR基因 C677T位点多态性与脑卒中有相关性 ,MTHFR基因可能是脑卒中的一个易感基因。     

Regulation of human methylenetetrahydrofolate reductase by phosphorylation

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the reduction of methylenetetrahydrofolate to methyltetrahydrofolate, the methyl donor for the conversion of homocysteine to methionine. Regulation of MTHFR activity is crucial for maintaining cellular concentrations of methionine and S-adenosylmethionine (AdoMet). Purified recombinant human MTHFR expressed in insect cells is multiply phosphorylated on an N-terminal extension of the protein that contains a highly conserved serine-rich region. Treatment by alkaline phosphatase removes seven phosphoryl groups from the enzyme. Thr-34 was identified as one of the seven phosphorylation sites by using a monoclonal antibody directed toward pThr-Pro. Mutation of Thr-34 to Ala completely blocks modification as judged by mass spectrometric analysis, suggesting that Thr-34 is the priming phosphorylation site. The Thr34Ala mutant was expressed in baculovirus-infected insect cells, and its enzymic properties were compared with wild-type enzyme. The mutant enzyme and alkaline phosphatase-treated wild-type enzyme are more active than untreated wild-type enzyme and less sensitive to inhibition by saturating AdoMet, indicating that phosphorylation at Thr-34 is critical for allosteric regulation of human MTHFR activity by AdoMet. The absence of methionine and the presence of adenosine in the cell culture medium, which lead to a low intracellular AdoMet/S-adenosylhomocysteine ratio, are associated with faster electrophoretic mobility of MTHFR, presumably because of less or no phosphorylation. Because the faster-mobility MTHFR is associated with the more active form of MTHFR, this response is likely to increase methionine production. Those observations suggest that AdoMet functions not only as an allosteric inhibitor but also to control phosphorylation of human MTHFR.     

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。     

Effect of common methylenetetrahydrofolate reductase gene mutation on coronary artery disease in familial hypercholesterolemia

Familial hypercholesterolemia (FH) is an autosomal dominant disorder characterized by primary hypercholesterolemia and premature coronary artery disease (CAD). However, the development of CAD in FH shows considerable interindividual variations. Elevated levels of plasma homocysteine have been recognized as independent risk factors for CAD. A 5,10-methylenetetrahydrofolate reductase (MTHFR) gene mutation (valine [V] was substituted for alanine [A]) has been reported to be associated with elevated levels of plasma homocysteine in mutant homozygotes (i.e., VV). We studied 199 consecutive male heterozygous FH patients, 99 with and 100 without CAD. In the CAD group, genotype VV and V alleles were significantly more frequent than in the non-CAD group (15% vs 7% in genotypes [p = 0.035] and 0.41 vs 0.30 in alleles [p = 0.017]). The mean ages at onset in the CAD group were 50, 51, and 43 years for genotypes AA, AV, and VV, respectively (p <0.05); the age of onset of CAD in genotype VV was significantly lower than in the other 2 genotypes. Kaplan-Meier survivor curves indicated that the development of CAD was significantly accelerated by MTHFR mutation, probably in a gene dose-dependent manner. Furthermore, only MTHFR genotype VV was shown to be an independent predictor of the early onset of CAD in a stepwise multiple regression analysis. The mean plasma homocysteine levels of genotype VV were significantly higher than those of the other 2 genotypes. Thus, the MTHFR mutation appears to accelerate the onset of CAD through elevation of plasma homocysteine levels in male heterozygous patients with FH.     

Genetic polymorphisms in the methylenetetrahydrofolate reductase and thymidylate synthase genes and risk of hepatocellular carcinoma

Methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TYMS) are known to play a role in DNA methylation, synthesis, and repair. The genetic mutations in MTHFR and TYMS genes may have influences on their respective enzyme activities. Data on the association studies of the MTHFR and TYMS genetic polymorphisms and risk of hepatocellular carcinoma (HCC) are sparse. MTHFR and TYMS genotypes were determined on 365 HCC cases and 457 healthy control subjects among Hispanic and non-Hispanic whites and African-Americans in Los Angeles County, California, and among Chinese in the city of Nanning, Guangxi, China. Relative to the high-activity genotype, each low-activity genotype of MTHFR was associated with a statistically nonsignificant 30% to 50% reduction in risk of HCC. Relative to the TYMS3'UTR +6/+6 genotype, individuals with 1 or 2 copies of the deletion allele had a statistically significant 50% reduction in risk of HCC. When we examined HCC risk by the total number of mutant alleles in the 3 polymorphic loci of MTHFR/TYMS (range, 0-4), there was a monotonic decrease in risk with increasing number of mutant alleles (P for trend = 0.003). Individuals possessing the maximum number of mutant alleles (i.e., 4) had an odds ratio of 0.46 (95% confidence interval = 0.23-0.93) for HCC compared with those with no or only 1 mutant allele. CONCLUSION: This study supports the hypothesis that reduced MTHFR activity and enhanced TYMS activity, both of which are essential elements in minimizing uracil misincorporation into DNA, may protect against the development of HCC.     

甲烯四氢叶酸还原酶基因多态性与糖尿病大血管病变的关系研究

目的探讨甲烯四氢叶酸还原酶(MTHFR)基因C677T位碱基突变与2型糖尿病患者同型半胱氨酸(Hcy)水平和糖尿病大血管病变的关系。方法将患者分为对照组、糖尿病颈动脉内中膜厚度(IMT)正常组、糖尿病IMT增厚组。应用酶联免疫法测定Hcy水平,采用多聚酶链反应-限制性内切酶片段长度多态性技术(PCR-RFLP)检测MTHFRC677T基因型,用高分辨彩色多普勒检查颈动脉内中膜厚度(IMT)。结果糖尿病IMT增厚组MTHFR基因的TT基因型和T等位基因频率显著增高,与糖尿病IMT正常组及对照组存在统计学差异(P<0.05)。对照组与糖尿病IMT正常组之间T等位基因频率无统计学差异。MTHFR基因突变者血浆Hcy增高。糖尿病组MTHFR基因突变者IMT值明显高于无基因突变者。结论糖尿病IMT增厚组T等位基因频率增高。MTHFR基因C677T点突变组血浆Hcy水平升高,颈动脉IMT增厚。推测MTHFR基因C677T点突变可能是糖尿病合并大血管病变发病的重要遗传因素。     

亚甲基四氢叶酸还原酶基因多态性对高血压患者冠心病发病的影响

目的　了解亚甲基四氢叶酸还原酶 (methylenetetrahydrofolatereductase ,MTHFR)基因的C6 77T突变对于高血压患者冠心病发病的作用。方法　所有入选的高血压病患者均行冠状动脉 (冠脉 )造影检查。冠脉造影正常 4 5例 (对照组 ) ,冠心病 5 8例 (病例组 )。使用高效液相色谱仪分析测定血浆同型半胱氨酸 (homocysteine,HCY) ,同时应用放射免疫法测定血浆叶酸水平 ,并采用聚合酶链反应 (PCR)检测MTHFR基因型。结果　MTHFR基因的T等位基因频率在冠心病组和对照组分别为0 45和 0 33(P =0 0 3)。MTHFR基因TT基因型与冠心病显著相关。冠心病组血浆HCY水平明显高于对照组 (1 7 73± 2 2 2 μmol/L比 1 2 1 8± 1 2 3μmol/L ,P =0 0 37) ,但两组叶酸水平差异无统计学意义。结论　TT型MTHFR可导致血浆HCY浓度升高 ,并且成为高血压患者发生冠心病的独立危险因素。     

Genetic polymorphisms in methylenetetrahydrofolate reductase and thymidylate synthase and risk of pancreatic cancer.

BACKGROUND & AIMS: Human pancreatic cancer might be associated with folate deficiency and impaired metabolism. We tested this hypothesis by examining the contribution of functional polymorphisms in methylenetetrahydrofolate reductase (MTHFR) and thymidylate synthase (TS) to risk of cancer. METHODS: DNA from 163 pancreatic cancer patients and 337 control subjects was genotyped for MTHFR (677C > T and 1298A > C) and TS (5'-untranslated region tandem repeat and G/C). Association with risk of pancreatic cancer was estimated by logistic regression. All statistical tests were two-sided. RESULTS: We observed an increased risk of pancreatic cancer associated with the MTHFR 677CT (odds ratio [OR], 2.60; 95% confidence interval [CI], 1.61-4.29; P = .0005) or 677TT (OR, 5.12; 95% CI, 2.94-9.10; P < .0001) genotype compared with the MTHFR CC genotype. An increased risk of pancreatic cancer was also associated with the TS 3Rc/3Rc genotype (OR, 2.19, 95% CI, 1.13-4.31; P = .022) compared with the TS 3Rg/3Rg genotype. Joint effect between MTHFR C677T polymorphism and smoking or drinking increased risk of pancreatic cancer in a super-multiplicative manner. The ORs for smoking, the polymorphism, and both factors combined were 0.70 (95% CI, 0.30-1.63), 2.17 (95% CI, 1.17-4.21), and 3.10 (95% CI, 1.54-6.51), respectively. This joint effect was much stronger in heavy smokers (OR, 6.69; 95% CI, 3.39-13.63; P < .0001). The ORs for drinking, the polymorphism, and both factors combined were 0.98 (95% CI, 0.40-2.30), 2.81 (95% CI, 1.65-4.98), and 4.39 (95% CI, 2.25-8.78), respectively. CONCLUSION: The MTHFR and TS polymorphisms are genetic determinants for developing pancreatic cancer.     

Identification of six methylenetetrahydrofolate reductase (MTHFR) genotypes resulting from common polymorphisms: impact on plasma homocysteine levels and development of coronary artery disease

Although three common MTHFR polymorphisms (C677T, A1298C, T1317C) have been reported, only polymorphism C677T has been investigated intensively as a risk factor for coronary artery disease (CAD). We investigated polymorphism frequencies, allelic associations and the effect of the resulting MTHFR genotypes on total plasma homocysteine (tHcy) levels and on coronary risk in a case-control study with 1000 angiographically confirmed Middle-European CAD patients and 1000 matched controls. Three out of four theoretically possible MTHFR haplotypes were detected: *1 (677C, 1298A), *2 (677T, 1298A), and *3 (677C, 1298C). The frequencies were *1: 36.4 and 34.4%; *2: 30.8 and 32.3%; and *3: 32.8 and 33.3%, in cases and controls, respectively. Only one patient was heterozygous for 1317C. None of the six resulting genotypes showed significant influence on tHcy levels. Moreover, there was no significant association with CAD risk or with disease severity or early disease manifestation. In the subgroup presenting with acute coronary syndromes, MTHFR genotypes *2/*3 and *3/*3 were surprisingly underrepresented (relative risk of *3/*3, 0.40; 95% confidence interval 0.20-0.79, P=0.009). We conclude from our genotype-based analysis that, in this well-fed Middle-European population, the observed common allelic variants of the MTHFR gene have no significant influence on tHcy levels or on the chronic process of CAD development.     

Associations between maternal methylenetetrahydrofolate reductase polymorphisms and adverse outcomes of pregnancy: the Hordaland Homocysteine Study

PURPOSE: Methylenetetrahydrofolate reductase (MTHFR) is involved in the metabolism of folate and homocysteine; a polymorphism in the MTHFR gene (677C-->T) has been associated with adverse outcomes of pregnancy. We studied whether two polymorphisms in the MTHFR gene (677C-->T and 1298A-->C) are associated with pregnancy complications, adverse outcomes, and birth defects. METHODS: MTHFR polymorphisms were determined in blood collected in 1992 and 1993 from 5883 women aged 40 to 42 years, and linked with 14,492 pregnancies in the same women recorded in the Medical Birth Registry of Norway from 1967 to 1996. RESULTS: The 677TT genotype in mothers was associated with increased risk of placental abruption (odds ratio [OR] = 2.6; 95% confidence interval [CI]: 1.4 to 4.8) compared with the CC variant. The risk of intrauterine growth restriction increased with number of T alleles (P for trend = 0.04). Compared with the 1298AA variant, the CC variant was associated with a reduced risk of very low birth weight infants (OR = 0.4; 95% CI: 0.2 to 0.8). No significant associations were found between MTHFR polymorphisms and birth defects. CONCLUSION: The maternal MTHFR 677C-->T polymorphism was a risk factor for placental abruption. The unexpected protective effect of the 1298A-->C polymorphism on very low birth weight needs further study.     

Influence of methylenetetrahydrofolate reductase polymorphisms on efficacy and toxicity of methotrexate in patients with juvenile idiopathic arthritis

OBJECTIVE: To study the relationship of C677T and A1298C polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene to toxicity and efficacy of methotrexate (MTX) in patients with juvenile idiopathic arthritis (JIA). METHODS: Single nucleotide polymorphisms of the MTHFR gene were investigated by polymerase chain reaction and restriction enzyme analysis of DNA extracted from peripheral blood cells. The fasting plasma homocysteine concentration was analyzed by enzyme immunoassay. Clinical data of 58 patients with JIA treated with MTX were analyzed retrospectively. RESULTS: The 1298A/A genotype was present in 31 patients, 1298C/C in 4 patients, and 21 patients were heterozygous. The 677C/C genotype was present in 29 patients, 677 T/T in 3 patients, and 26 patients were heterozygous. In patients who presented the C allele of the A1298C polymorphism, improvement with respect to the number of swollen joints, the number of tender joints, and a decrease in erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) levels occurred more frequently than in 1298 A/A homozygous patients (p < 0.05 for ESR, p < 0.01 for CRP, chi-square test). There was no relationship between the C677T polymorphism and the efficacy of MTX treatment. Forty-two adverse events were noted in 26 patients; gastrointestinal symptoms were most common (n = 20), followed by elevated serum levels of transaminases (n = 19) and hair loss (n = 3). There was no cytopenia. Patients with the heterozygous genotype 677C/T exhibited adverse events more frequently than patients with the homozygous C/C genotype (65% vs 31%; p < 0.05, chi-square test). The A1298C polymorphism, however, was not associated with occurrence of adverse events. Plasma homocysteine was elevated in 6 patients with up to 16.9 mmol/l. No association was found to a specific genotype or to adverse events. CONCLUSION: These preliminary data suggest an association of the MTHFR 677C/C polymorphism to a higher tolerability of MTX, and of the 1298A/A to lower clinical efficacy of MTX therapy in JIA.     

MTHFR基因多态性及血浆同型半胱氨酸水平与冠心病的关系

目的研究亚甲基四氢叶酸还原酶（m ethylenetetrahydrofolate reductase,MTHFR）基因677位单核苷酸多态性（C-T）与血浆同型半胱氨酸（homocyste ine,Hcy）水平及冠心病之间的关系。方法用多聚酶链式反应-限制性片段多态性（RFLP）方法检测122例冠心病患者（冠脉造影显示至少有1支血管狭窄≥50%）与56例对照组（冠脉造影未发现任何可辨认斑块或狭窄）的MTHFR 677位单核苷酸多态性（C-T）;用荧光衍生化后高效液相色谱法（h igh?perform ance liqu id chrom atography,HLPC）检测血浆总Hcy水平。结果①冠心病组Hcy浓度高于对照组（P<0.05）。②冠心病组中TT、TC、CC的基因型频率分别为30%、45%、25%;T等位基因频率为53%,C等位基因频率为47%。在对照组中TT、TC、CC的基因型频率分别为25%、32%、43%;T等位基因频率为41%,C等位基因频率为59%。两组基因型分布和等位基因频率分布差异有显著性（均P<0.05）。③两组的TT基因型者血浆Hcy浓度均显著高于CC和TC基因型者（P<0.05）,而后两者间无显著性差异。结论MTHFR基因C677T点突变对冠心病发病有一定的关系。MTHFR基因纯合突变是引起高Hcy血症的一个重要的遗传因素。     

Prospective evaluation of the risk conferred by factor V Leiden and thermolabile methylenetetrahydrofolate reductase polymorphisms in pregnancy

Factor V (FV) Leiden and thermolabile methylenetetrahydrofolate reductase (MTHFR) are 2 common polymorphisms that have been implicated in vascular thrombosis. We determined whether these mutations predicted an adverse outcome in pregnancy. Second, we looked for an interaction between these 2 mutations in patients with recurrent fetal loss or thrombosis in pregnancy. Primigravid subjects at their booking visit to the National Maternity Hospital (Holles Street, Dublin, Ireland) were screened for the polymorphisms. Thermolabile MTHFR and FV Leiden genotypes were detected by either restriction fragment length polymorphism or heteroduplex capillary chromatography. The carrier frequency of FV Leiden in the screened primigravid population was 2.7% (allele frequency 1.36%), all being heterozygous for the mutation. This value was lower than expected from previous studies in European populations. Forty-nine percent of the screened population (289 of 584) were heterozygous for thermolabile MTHFR, and 10.6% were homozygous (62 of 584). The frequency of the 2 polymorphisms was no higher in those who subsequently developed preeclampsia (n=12) or intrauterine growth retardation (n=9), and none of the screened population developed thrombosis. However, the frequency of FV Leiden was higher in patients who subsequently miscarried after the first trimester of pregnancy (allele frequency of 5.5%, P=0.0356). Among those positive for FV Leiden, 3 of 27 miscarried, compared with 24 of 572 of FV Leiden-negative patients (11% versus 4.2%). No interaction was found between the 2 mutations in the control or patient populations. In patients with a prior history of venous thrombosis, the carrier rate of FV Leiden was increased (4 of 33, allele frequency of 7.6%, P=0. 0115). In contrast, the carrier frequency for thermolabile MTHFR was no higher, and there was no interaction between the 2 mutations. Neither mutation occurred at a significantly higher frequency in patients with a prior history of recurrent fetal loss. In conclusion, FV Leiden is a risk factor for thrombosis in pregnancy and possibly for second-trimester miscarriage independent of thermolabile MTHFR. However, prospective analysis suggests that the risk conferred by FV Leiden is low in a primigravid population. The thermolabile MTHFR genotype was not implicated in any adverse outcome.     

血中同型半胱氨酸和亚甲基四氢叶酸还原酶C677T基因多态性与脑血管狭窄的关系

目的探讨血中同型半胱氨酸(HCY)水平及其代谢酶———亚甲基四氢叶酸还原酶(MTHFR)C677T基因多态性与脑血管狭窄的关系。方法采用回顾性病例对照研究的方法,纳入脑血管狭窄患者85例,其中单纯颅内动脉狭窄40例,单纯颅外动脉狭窄45例。选择同期年龄和性别匹配的无脑血管狭窄者65例作为对照组。采用荧光偏振免疫法和聚合酶链反应-限制片段长度多态性技术,测定和分析各组血浆HCY水平和MTHFR C677T基因多态性。结果①脑血管狭窄组患者血浆HCY水平中位数[11.00(8.05～15.00)μmol/L]高于对照组[8.40(5.50～10.95)μmol/L],差异有统计学意义(P<0.05)。与对照组相比,颅内动脉狭窄组[11.75(8.10～15.25)μmol/L]和颅外动脉狭窄组[9.00(8.00～14.05)μmol/L]HCY水平均升高(P<0.05)。②在脑血管狭窄组和对照组中,MTHFR C677T基因突变TT纯合子的HCY水平中位数分别为[16.00(11.93～17.30)μmol/L]、[12.90(8.90～14.05)μmol/L],高于CC无突变纯合子者的[9.00(8.00～12.80)μmol/L]、[8.60(5.10～11.05)μmol/L],P<0.05。③多因素Logistic回归分析显示,高HCY血症(OR=2.686,95%CI:1.051～6.869,P=0.039)、高血压(OR=2.431,95%CI:1.226～4.822,P=0.011)是脑血管狭窄的独立危险因素。MTHFR C677T基因型多态性不是脑血管狭窄的独立危险因素(P=0.909)。结论高同型半胱氨酸血症可能是脑血管狭窄的危险因素。MTHFR C677基因型突变是影响HCY水平的重要因素,但与脑血管狭窄无明确关系。     

Folate levels in mucosal tissue but not methylenetetrahydrofolate reductase polymorphisms are associated with gastric carcinogenesis

INTRODUCTION Methylation of gene regulatory elements is a well-documented epigenetic change that can lead to gene inactivation. Human gastric carcinogenesis is suggested to be associated with the decrease of total genomic DNA methylation, hypomethylation …     

Annotation Molecular genetics of methylenetetrahydrofolate reductase deficiency

Summary In severe MTHFR deficiency with neonatal or adolescent onset, 9 rare mutations have been identified. In mild MTHFR deficiency with thermolabile enzyme, a single common mutation (an alanine-to-valine substitution) is involved, but a genetic-nutrient interactive effect is required to produce mild hyperhomocysteinaemia. This interactive effect has been proposed to be a risk factor for arteriosclerosis and for neural-tube defects. Large-scale studies are required for confirmation of the role of MTHFR in these multifactorial processes as well as to assess its role in other folate-dependent disorders.     

Relation of a common methylenetetrahydrofolate reductase mutation and plasma homocysteine with intimal hyperplasia after coronary stenting

BACKGROUND: Hyperhomocysteinemia has been identified as an independent risk factor for coronary artery disease. Recent studies have shown that a common mutation (nucleotide 677 C-->T) in the methylenetetrahydrofolate reductase (MTHFR) gene may contribute to mild hyperhomocysteinemia and, therefore, to the incidence of coronary artery disease. No information exists, however, regarding the association between the mutation of the MTHFR gene or plasma homocysteine levels and morphological analysis of coronary atherosclerosis using intravascular ultrasound. METHODS AND RESULTS: To examine the potential influence of MTHFR genotype and homocysteine on coronaryarteries morphologically, we screened 62 patients with 65 lesions that were treated with 93 Palmaz-Schatz stents. The plasma homocysteine levels in the patients with the TT genotype were not significantly higher than those in the patients with non-TT (CC+CT) genotypes (13.1 +/- 5.5 versus 11.5 +/- 3.1 mmol/L, P=0.16). Angiographic analysis showed that the percent diameter stenosis in the patients with the TT genotype was significantly greater than that in those with non-TT genotypes (43.7 +/- 17.8% versus 29.0 +/- 22.0%, P=0.015). Intravascular ultrasound analysis showed that the TT genotype was significantly associated with greater intimal hyperplasia area (5.70 +/- 1.94 versus 3.72 +/- 1.38 mm2, P=0.001). In multiple stepwise regression analysis, the number of the T alleles was the only independent predictor of intimal hyperplasia after intervention (r2=0.21, P=0.004). CONCLUSIONS: The homozygous mutant genotype of the MTHFR gene may increase the risk of in-stent restenosis more than does the normal homozygous or heterozygous genotype.