妊高征患者亚甲基四氢叶酸还原酶基因多态的检测

目的　探讨妊高征患者亚甲基四氢叶酸还原酶 (MTHFR)基因C6 77T多态与血浆同型半胱氨酸 (Homo cysteine ,Hcy)、叶酸及维生素B12 水平的关系。方法　采用 (PCR -RFLPCPR -restrictionfragmentlengthpolymdor phism)法对 82例妊高征患者 (Hcy血症组和无Hcy血症组 )及 90例正常孕妇 (对照组 )进行MTHFR基因C6 77T等位基因检测 ,并同时测量孕妇血浆中的同型半胱氨酸、叶酸和维生素B12 水平。结果　妊高征组A(Hcy血症组 )纯合变异型T6 77/T6 77频率 (0 34)显著高于妊高征组B(无Hcy血症组 ) (0 11,P <0 0 1)和正常对照组 (0 13,P <0 0 1) ;各组中随 6 77T等位基因数量的增加 ,血浆Hcy水平也增加 ,但是对叶酸和维生素B12 水平没有明显影响。结论　MTH FR基因C6 77T多态可以导致妊高征孕妇血液中同型半胱氨水平升高 ,MTHFR基因C6 77T多态是妊高征发病的遗传危险因素之一     

血浆同型半胱氨酸与肾移植手术的关系探讨

目的:探讨血浆总同型半胱氨酸(tHCY)水平与肾移植手术的关系。方法:应用荧光偏振免疫法(FPIA)测定40例正常人、47例肾移植术后患者和30例慢性肾功能不全(CRF)患者的血浆tHCY水平,并对20例肾移植患者(连续监测组)手术前后的血浆tHCY水平进行连续1周的检测。结果:各组血浆tHCY水平均以(x±s)表示,对照组为10.12±3.15μmol/L;肾移植后患者为15.78±5.24μmol/L,CRF患者为19.68±6.74μmol/L。连续监测组手术前、下术后 tHCY水平分别为18.46±7.57μmol/L、13.01±5.56μmol/L。肾移植术后患者、CRF患者、连续监测组患者手术前、后血浆tHCY水平与正常对照组相比均有显著性差异(P＜0.001)。连续监测组患者手术前tHCY水平与其手术后相比有显著性差异(P＜0.001)。结论:肾移植术后患者、CRF患者血浆tHCY水平与正常人相比有显著性差异(P＜0.001),肾功能小全是引起肾移植后患者高tHCY血症的主要原因。     

MTHFR基因C677T位点多态性与胎儿生长受限的相关性

目的:探讨亚甲基四氢叶酸还原酶(MTHFR)基因C677T位点多态性与胎儿生长受限(FGR)的关系。方法:FGR患者62例,正常妊娠妇女65例。聚合酶链反应—限制性内切酶片段长度多肽性(PCR-RFLP)法检测MTHFR C677T基因多态性;荧光偏振免疫法测定血浆总同型半胱氨酸水平;微粒子酶免分析法测定血浆叶酸、VitB12浓度。结果:①FGR组MTHFR C677TC/T基因型频率显著高于正常对照组,C/C基因型频率显著低于对照组,总的突变T等位基因频率显著高于对照组(P<0.05)。②FGR组MTHFRT/T基因型Hcy水平较C/C、C/T基因型患者显著增高,而血清叶酸水平则明显降低(P<0.05)。血清VitB12水平在FGR3种基因型之间差异无显著性(P>0.05)。对照组MTHFR C677T3种基因型之间血清Hcy、叶酸、VitB12,水平差异无显著性(P>0.05)。结论:MTHFR基因C677T位点多态性与FGR有关,高同型半胱氨酸血症是FGR发病的危险因素。     

MTHFR C677T 基因多态性及血浆HCY与复发性流产的关系

目的 探讨MTHFR C677T基因多态性及血浆同型半胱氨酸与复发性流产发病的相关性.方法 采用聚合酶链反应-限制性片段长度多态性分析MTHFR C677T的基因型并以小分子捕获(small molecular trapping,SMT)技术测定血浆HCY水平.结果 流产组MTHFR C677TT基因型频率和T等位基因频率高于对照组(P＜0.05);流产组与对照组比较血浆HCY水平显著增高(P＜0.001).结论 患者MTHFR C677T突变及血浆HCY水平的增高与复发性流产的发生有相关性.     

奎文区成年人同型半胱氨酸水平及关键代谢酶基因多态性研究

目的调查潍坊市奎文区成年居民H型高血压检出比例、血浆同型半胱氨酸(Hcy)水平,探讨血浆同型半胱氨酸关键代谢酶亚甲基四氢叶酸还原酶(MTHFR C677T)基因多态性与H型高血压的关系,为制定有效的高血压防治措施提供科学依据。方法采用聚合酶链反应-限制性片段长度多态性(PCR-RFLR)方法,对潍坊市奎文区740例成年人进行MTHFR C677T基因型分型和血浆Hcy水平检测。结果调查人群H型高血压检出比例为16.35%,男性高于女性,差异具有统计学意义(P0.05);所调查的人群Hcy水平为13.58±9.02,男性高于女性,差异具有统计学意义(P0.05);男性、女性MTHFR C677T基因TT、CT、CC基因频率分布,差异具有统计学意义(P0.05);H型高血压人群MTHFR C677T基因CC+CT和TT基因型频率与正常血压、非H型高血压人群比较,差异具有统计学意义(P0.05)。结论奎文区居民的H型高血压检出比例、血浆Hcy水平均偏高且存在性别差异,MTHFR C677T基因纯合突变可能是引起Hcy水平升高,进而引发H型高血压的重要遗传因素。     

血浆同型半胱氨酸水平及MTHFR基因多态性与阿尔茨海默病的关系

目的 探讨血浆同型半胱氨酸(Hcy)水平及MTHFR基因多态性与阿尔茨海默病(AD)的关系. 方法 选取43例AD患者(AD组),应用高效液相色谱-电化学检测(HPLC-ED)法测定血浆Hcy水平,应用聚合酶链反应-限制性片段长度多态性(PCR-RFLP)检测MTHFR基因多态性,同时测定血浆叶酸、维生素B12水平,并与40例健康老年人(对照组)比较. 结果 AD组血浆Hcy水平为(25.43±5.60)μmol/L,显著高于对照组的(9.81±2.86)μmol/L(P＜0.01),血浆叶酸、维生素B12水平明显低于对照组(P＜0.05);MTHFR基因型有3种,即纯合子(T/T)型、杂合子(T/C)型和纯合子(C/C)型,两组MTHFR基因型和等位基因频率比较差异均无统计学意义(P＞0.05). 结论 高Hcy血症是AD发生和发展的一个重要危险因素.     

血浆同型半胱氨酸水平及亚甲基四氢叶酸还原酶基因突变与脑卒中关系的病例对照研究

目的 探讨中国人脑卒中与血浆同型半胱氨酸(Hcy)水平及N~5N~(10)亚甲基四氢叶酸还原酶(MTHFR)基因突变的关系。方法 收集脑卒中患者300例为病例组,选择300名性别、年龄和种族等与病例组相匹配的无脑卒中者作为对照组,采用高效液相色谱的方法检测两组的血浆Hcy水平,并通过聚合酶链反应和限制性酶切的方法对其MTHFR C677T基因型进行鉴定,统计分析血浆Hcy水平与脑卒中的关系,以及MTHFR C677T基因突变与脑卒中发生的关系及其对血浆Hcy水平的影响。结果 脑卒中组血浆Hcy水平显著高于对照组[(16`92±3.43)μmol/L vs.(14.57±2.59)μmol/L,P<0.05];MTHFR C677T基因突变率在脑卒中组与对照组之间差异无统计学意义(P>0.05),在脑溢血和脑梗死组之间差异也无统计学意义(P>0.05);MTHFR C677T基因变异对血浆Hcy水平无明显影响[(15.28±2.17)μmol/L vs.(15.11±3.81)μmol/L,P>0.05]。结论 血浆Hcy水平升高在中国人脑卒中的发生中起着重要的作用,而Hcy代谢过程中的关键酶MTHFR基因的C677T突变与血浆Hcy水平无明显关系,而且与脑卒中的发生无相关性,因此控制血浆Hcy水平在预防心脑血管疾病的发生中有重要意义。     

同型半胱氨酸与脑梗死关系的实验研究

目的探讨血浆同型半胱氨酸和脑梗死之间的关系。方法测定120例脑梗死患者及41例健康对照者的血浆同型半胱氨酸、维生素B12和叶酸水平。结果脑梗死组的血浆同型半胱氨酸水平(17.15±4.63)μmol/L显著高于对照组(10.12±2.62)μmol/L,P<0.01;血浆同型半胱氨酸水平与叶酸和维生素B12均呈负相关;男女患者之间同型半胱氨酸的差异有显著性(P<0.01);高血压脑梗死患者的同型半胱氨酸水平高于单纯脑梗死患者(P<0.01)。结论同型半胱氨酸是脑梗死的一个重要发病因素,血浆同型光胱氨酸水平与叶酸和维生素B12均呈负相关,雌激素水平对血浆同型半胱氨酸也有影响,高同型半胱氨酸血症与高血压性脑梗死有关。     

体检人群血清同型半胱氨酸水平与MTHFRC677T基因型频率的调查

目的调查北京地区体检人群血清同型半胱氨酸(Hcy)水平及其代谢酶亚甲基四氢叶酸还原酶(MTHFR)基因的C677T基因型分布情况。方法利用全自动生化分析仪循环酶法检测892例体检者血清同型半胱氨酸水平,采用微测序法检测MTHFR C677T基因多态性,并进行基因分型。结果 TT基因型受检者血清Hcy水平高于CT基因型和CC基因型受检者水平,所调查的体检人群中男性血清Hcy水平显著高于女性,差异有统计学意义(P0.01)。结论MTHFR基因的C677T纯合突变型与血浆Hcy水平升高相关,此外健康人群血清Hcy水平存在年龄及性别差异。基因分型检测对于降低血清Hcy水平,预测脑卒中等心脑血管疾病具有重要意义。     

上海地区孕妇MTHFR C677T基因多态性与血浆同型半胱氨酸水平的关联性分析

目的 了解上海市孕妇MTHFR基因型的分布情况,分析MTHFR C677T基因多态性与高同型半胱氨酸血症的关联性,为高危孕妇的遗传筛查及围产期叶酸摄入的个性化提供依据。方法 选取上海市五所社区医院2015年1月~2015年6月门诊建卡孕妇1000例,随访了解基本信息、孕期危险因素暴露及叶酸摄入情况,以基因芯片法检测MTHFR基因型,循环酶法检测血浆同型半胱氨酸。结果 上海地区孕妇MTHFR C677T基因CC型、CT型、TT型的检出频率分别为33.0%、49.2%、17.8%,等位基因C、T的频率为57.6%、42.4%,样本人群处于H-W平衡状态。血浆同型半胱氨酸浓度为11.22（9.15,13.52）μmol/L,其中911例（91.6%）正常,84例（8.4%）属轻度高同型半胱氨酸血症。经多因素logistic回归分析,CT型与TT型发生高同型半胱氨酸血症的OR值分别为2.18（95%CI:1.11~4.25）和6.26（95%CI:3.13~12.53）。结论 MTHFR基因C677T多态性与孕妇血浆同型半胱氨酸水平存在关联,携带等位基因T者可视为高危孕妇,孕期叶酸补充可适量增加。     

2型糖尿病合并冠心病患者的同型半胱氨酸水平及代谢关键酶基因多态性特点

目的探讨中国北方地区糖尿病合并冠心病者同型半胱氨酸(Hcy)及其代谢相关酶亚甲基四氢叶酸还原酶(MTHFR)C677T及胱硫醚β-合成酶(CBS)844 ins 68基因多态性的特点。方法研究对象均为北方汉族人群,包括无血缘关系的70名糖尿病合并冠心病患者、71名糖尿病患者和85名健康人群。应用荧光偏振免疫法(FPIA)测定Hcy水平,应用微粒子酶免分析免疫法(MEIA)测定血浆叶酸、维生素B12浓度,同时测定血脂。应用聚合酶链反应分析MTHFR C677T与CBS844 ins 68基因多态性。结果糖尿病合并冠心病组(DM+CHD组)Hcy中位数为14.8μmol/L,显著高于DM组(11.1μmol/L)和对照组(11.2μmol/L),(P<0.01),DM组与对照组之间差异无显著性(P>0.05)。DM+CHD组的T等位基因频率(45%)明显高于糖尿病组(26.8%)和对照组(31.2%),(P<0.01)。三组CBS844 ins 68的基因型及等位基因频率差异无显著性(P>0.05)。本研究定义Hcy>15μmol/L为高Hcy血症(HHcy)。Logistic回归分析显示HHcy的OR值为4.547(95%CI1.970～10.496),(P<0.01);MTHFR677携带T基因的OR值为2.369(95%CI1.160～4.841),(P=0.018);CBS844 ins 68基因的OR值为0.384(95%CI0.033～4.423),(P=0.443)。结论HHcy、MTHFR677携带T基因可能是中国北方地区汉族人2型糖尿病合并冠心病发生的危险因素。     

A common mutation A1298C in human methylenetetrahydrofolate reductase gene: association with plasma total homocysteine and folate concentrations.

Methylenetetrahydrofolate reductase (MTHFR) is one of the main regulatory enzymes of homocysteine metabolism. Previous studies revealed that a common mutation in MTHFR gene C677T is related to hyperhomocysteinemia and occlusive vascular pathology. In the current study, we determined the prevalence of a newly described mutation in the human MTHFR gene A1298C, and the already known C677T mutation, and related them to plasma total homocysteine and folate concentrations. We studied 377 Jewish subjects, including 190 men and 186 women aged 56.8 +/- 13 y (range 32-95 y). The frequency of the homozygotes for the A1298C and the C677T MTHFR mutations was common in the Jewish Israeli population (0.34 and 0.37, respectively). Subjects homozygous (TT) for the C677T mutation had significantly greater plasma total homocysteine concentrations (P < 0.01) than subjects without the mutation (CC). Homozygotes (CC) for the A1298C mutation did not have elevated plasma total homocysteine concentrations. Our study indicated that subjects with the 677CC/1298CC genotype had significantly lower concentrations (P < 0. 05) than those with a 677CC/1298AA genotype. Neither mutation (the A1298C and the C677T) was associated with established cardiovascular risk factors such as hypertension, elevated total cholesterol or body mass index.     

Vitamin B-12 status is inversely associated with plasma homocysteine in young women with C677T and/or A1298C methylenetetrahydrofolate reductase polymorphisms

Methylenetetrahydrofolate reductase (MTHFR) polymorphisms may negatively influence one-carbon metabolism and increase health risks in women of reproductive age. The effect of MTHFR single nucleotide polymorphisms at bp 677 and/or 1298 and differences in folate and vitamin B-12 status on plasma homocysteine concentration in women of reproductive age (20-30 y; n = 186) were investigated. From the multivariate regression model, homozygotes (n = 23) for the C677T MTHFR variant had plasma homocysteine concentrations that were higher (P < 0.05) than those observed in the other 5 genotype groups, including those who were heterozygous for both variants (677CT/1298AC; n = 32). Plasma homocysteine was negatively associated with plasma vitamin B-12 concentration (P = 0.015) and serum folate (P = 0.049), with the degree of correlation between plasma vitamin B-12 and homocysteine concentrations dependent on MTHFR genotype. The C677T and A1298C MTHFR polymorphisms were significant predictors (P < 0.05) of plasma homocysteine when regression analysis was used to model plasma homocysteine concentration as a function of genotype, supplement use, serum folate and plasma vitamin B-12 concentration. Plasma homocysteine decreased as vitamin B-12 concentration increased (P = 0.0005) in individuals who were heterozygous for both the C677T and A1298C variants with nonsignificant trends (P = 0.114-0.128) in individuals homozygous for either the C677T or A1298C variants. In contrast, within the group of individuals with the wild-type genotype for both the C677T and A1298C MTHFR variants, homocysteine was not associated with changes in plasma vitamin B-12 concentrations. These data suggest that enhancing vitamin B-12 status may significantly decrease homocysteine in young women with C677T and/or A1298C MTHFR polymorphisms, even when vitamin B-12 concentrations are within the normal range.     

High plasma homocysteine is associated with the risk of coronary artery disease independent of methylenetetrahydrofolate reductase 677C-->T genotypes

Hyperhomocysteinemia is an independent risk factor for coronary artery disease (CAD). The aim of this study was to investigate the relations between the methylenetetrafolate reductase (MTHFR) 677C-->T genotypes, B-vitamins (folate, vitamin B-12 and B-6), homocysteine and the risk of CAD. In this case-control study, patients who were identified by cardiac catheterization as having at least 50% stenosis of one major coronary artery were assigned to the case group (n=121). Healthy individuals with normal blood biochemical values were assigned to the control group (n=155). Healthy subjects were matched to case subjects for age. The concentrations of plasma homocysteine, serum folate, vitamin B-12, plasma pyridoxal 5'- phosphate (PLP) and MTHFR 677C-->T gene polymorphism were obtained. The T-allele carriers had significantly higher plasma homocysteine concentration compared to subjects with the 677CC genotype. The MTHFR 677C-->T genotypes were associated with plasma homocysteine after adjusting for various potential risk factors in the case and pooled groups. The MTHFR genotypes were found to have no associations with the risk of CAD. However, plasma homocysteine (>or= 12.5 micromol/L) (OR, 3.49; 95% CI, 1.23-9.88) had a significant association with increased risk of CAD even after additionally adjusted folate status. High plasma homocysteine concentration had a direct effect on the risk of CAD independent of MTHFR 677C-->T genotypes.     

The relationship between riboflavin and plasma total homocysteine in the Framingham Offspring cohort is influenced by folate status and the C677T transition in the methylenetetrahydrofolate reductase gene

Methylenetetrahydrofolate reductase (MTHFR) catalyzes the synthesis of 5-methyltetrahydrofolate, the methyl donor for remethylation of homocysteine to methionine. The C677T MTHFR polymorphism is associated with mild hyperhomocysteinemia, but only in the presence of low folate status. Because MTHFR contains flavin adenine dinucleotide (FAD) as a prosthetic group, riboflavin status may also influence homocysteine metabolism. The objective of this study was to examine the association between riboflavin status and fasting plasma total homocysteine (tHcy) concentration while also considering MTHFR C677T genotype and folate status. The study was conducted using fasting plasma samples (n = 450) from the fifth examination of the Framingham Offspring Study cohort. All persons with the TT genotype and age- and sex-matched sets of individuals with the CT and CC genotypes were selected for determination of plasma riboflavin and flavin mono- and dinucleotide levels. Plasma riboflavin was associated with tHcy concentrations, but the association was largely confined to persons with plasma folate <12.5 nmol/L and TT genotype. In these persons, the mean tHcy among individuals with riboflavin levels <6.89 nmol/L was 14.5 micromol/L, whereas the mean tHcy for those with riboflavin > or = 11 nmol/L was 11.6 micromol/L (P-trend <0.03). Plasma flavin nucleotides were unrelated to tHcy concentrations. Our data suggest that riboflavin status may affect homocysteine metabolism, but only in a small segment of the population who have both low folate status and are homozygotes for the MTHFR C677T mutation.     

B-vitamins, homocysteine and gene polymorphism in adults with fasting or post-methionine loading hyperhomocysteinemia

Background  Although fasting and post-methionine loading (PML) homocysteine concentrations are not necessarily related, a high percentage of hyperhomocysteinemia cases would be missed if methionine loading was not performed. Aim of the study  The influences of B-vitamins and genetic polymorphism (methylenetetrahydrofolate reductase 677C → T, MTHFR 677C → T) on fasting and PML homocysteine concentrations and the relationship between fasting and PML homocysteine were studied. Methods  This study was a cross-sectional study. Healthy subjects were divided into either fasting hyper-homocysteinemia (≥12.2 μmol/l) (fasting hyper-hcy, n = 51), PML hyper-homocysteinemia (fasting homocysteine <12.2 μmol/l but PML homocysteine ≥25.6 μmol/l) (PML hyper-hcy, n = 29), or normo-homocysteinemia (fasting homocysteine <12.2 μmol/l and PML homocysteine <25.6 μmol/l) (normo-hcy, n = 118) group based on elevated fasting and PML homocysteine levels of the 75th percentile of the population. The concentrations of plasma fasting and PML homocysteine, serum folate, vitamin B-12, plasma pyridoxal 5′- phosphate (PLP) were measured. The genetic polymorphisms were determined. Results  Fasting homocysteine, but not PML homocysteine and MTHFR 677C → T genotype, was significantly and inversely affected by serum folate concentration after adjusting for potential confounders (β = −0.062, P < 0.01). Fasting and PML homocysteine were highly associated in the fasting hyper-hcy and pooled groups (P < 0.01) but not in the PML hyper-hcy and normo-hcy groups. PML homocysteine did not interact with either serum folate (P = 0.302), vitamin B-12 (P = 0.465), plasma PLP (P = 0.996) or MTHFR 677C → T genotype (P = 0.136) to affect fasting homocysteine concentration. Conclusions  Approximately one-third (36.3%) of hyperhomocysteinemia cases would be missed if methionine loading were not performed. Even though subjects may have a normal fasting homocysteine concentration, they need further screening for their PML homocysteine.     

Methionine synthase reductase 66A->G polymorphism is associated with increased plasma homocysteine concentration when combined with the homozygous methylenetetrahydrofolate reductase 677C->T variant

Methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) are important for homocysteine remethylation. This study was designed to determine the influence of genetic variants (MTHFR 677C-->T, MTHFR 1298A-->C, and MTRR 66A-->G), folate, and vitamin B-12 status on plasma homocysteine in women (20-30 y; n = 362). Plasma homocysteine was inversely (P < 0.0001) associated with serum folate and plasma vitamin B-12 regardless of genotype. Plasma homocysteine was higher (P < 0.05) for women with the MTHFR 677 TT/1298 AA genotype combination compared with the CC/AA, CC/AC, and CT/AA genotypes. Women with the MTHFR 677 TT/MTRR 66 AG genotype had higher (P < 0.05) plasma homocysteine than all other genotype combinations except the TT/AA and TT/GG genotypes. There were 5.4-, 4.3-, and 3.8-fold increases (P < 0.001) in risk for plasma homocysteine in the top 5, 10, and 20%, respectively, of the homocysteine distribution for subjects with the MTHFR 677 TT compared with the CC and CT genotypes. Predicted plasma homocysteine was inversely associated with serum folate (P = 0.003) and plasma vitamin B-12 (P = 0.002), with the degree of correlation dependent on MTHFR 677C-->T genotype. These data suggest that coexistence of the MTHFR 677 TT genotype with the MTRR 66A-->G polymorphism may exacerbate the effect of the MTHFR variant alone. The potential negative effect of combined polymorphisms of the MTHFR and MTRR genes on plasma homocysteine in at-risk population groups with low folate and/or vitamin B-12 status, such as women of reproductive potential, deserves further investigation.     

The methylenetetrahydrofolate reductase 677C->T polymorphism and dietary folate restriction affect plasma one-carbon metabolites and red blood cell folate concentrations and distribution in women

Whether folate status and the methylenetetrahydrofolate reductase (MTHFR) 677C-->T polymorphism interact to affect methionine-cycle metabolite concentrations is uncertain. We evaluated the effects of dietary folate restriction on relations among folate status indices and plasma concentrations of methionine cycle metabolites in women with the MTHFR 677 C/C and T/T genotypes. Healthy, normohomocysteinemic women (n = 18; 20-30 y old) of adequate B vitamin status, and equally divided according to MTHFR 677C-->T genotype (9 C/C and 9 T/T) were recruited. Folate status indices and methionine cycle metabolites were measured in blood samples collected at baseline and after 7 wk of dietary folate restriction (115 microg dietary folate equivalents/d). Significant negative correlations between plasma total homocysteine concentrations and total or 5-methyl folate concentrations (P = 0.041 and 0.023, respectively) in RBCs were found only in T/T subjects. Formylated folates were detected in RBCs of T/T subjects only, and their abundance was predictive of plasma total homocysteine concentration despite no significant alteration by folate restriction. Plasma concentrations of S-adenosylmethionine and S-adenosylhomocysteine were not significantly affected by dietary folate restriction and the MTHFR 677 T/T genotype. In conclusion, plasma total homocysteine concentrations in subjects with the MTHFR 677 T/T genotype were inversely related to 5-methyl folate concentrations and directly related to formylated folate concentrations in RBCs, even though the latter were not significantly affected by moderate folate restriction.