血浆同型半胱氨酸水平及MTHFR基因多态与血管性痴呆的关系

目的探讨血浆同型半胱氨酸(H cy)水平及M THFR基因多态与血管性痴呆(VD)的关系。方法应用高效液相色谱仪和电化学检测法测定37例VD患者的血浆总H cy水平,并与40例同龄对照组及40例非痴呆脑梗死组比较,运用多聚酶链反应-限制性内切酶片段长度多态性技术(PCR-RFLP)检测M THFR基因多态性,同时测定血浆叶酸及维生素B12水平。结果VD患者血浆总H cy水平显著高于同龄对照组(P<0.001)和非痴呆脑梗死组(P<0.05);M THFR基因型有3种,即纯合子(T/T)型,杂合子(T/C)型,纯合子(C/C)型。3组基因型和等位基因频率相比,差异均无显著性(P>0.05);VD组血浆叶酸及维生素B12水平明显低于同龄对照组(P<0.05)和非痴呆脑梗死组(P<0.05)。结论高同型半胱氨酸血症是VD发病的一个新的危险因素。     

帕金森病患者血浆同型半胱氨酸水平及其代谢相关酶基因多态性分析

目的　 探讨高同型半胱氨酸 (Hcy)血症及其代谢酶基因多态性与帕金森病 (PD)的关系。方法　 分为PD组 30例、神经系统其他疾病组 33例和正常老年组 6 0例 ,测定被检者血浆Hcy浓度、血叶酸和维生素B12 浓度等 ,并且检测亚甲基四氢叶酸还原酶 (MTHFR)基因C6 77T、胱硫醚 β 合成酶 (CBS)基因 84 4ins6 8和甲硫氨酸合成酶(MS)基因A2 75 6G的基因表型。结果　PD组血Hcy浓度明显高于神经系统其他疾病组和正常老年组(P <0 .0 1) ;经相关回归分析显示PD组的血Hcy水平与维生素B12 呈负相关。此外 ,MTHFRC6 77T纯合突变型的Hcy水平均显著高于野生型和杂合突变型。结论 　本文证实C6 77T纯合子突变可能是导致血浆tHcy水平升高的遗传决定簇。因此 ,补充营养元素叶酸、维生素B12 可能有助于降低Hcy水平及其危险因素 ;有必要对人群进行MTHFR基因多态性筛选。     

MTHFR基因多态性及同型半胱氨酸与青年脑血管病的关系

目的:研究Ns,N10-亚甲基四氢叶酸还原酶(MTHFR)基因多态性及血浆同型半胱氨酸(Hcy)水平与青年脑血管病的关系。方法:研究对比40例青年脑血管病患者(首次发病年龄≤50岁)及32例健康青年人的MTHFR基因多态性及血浆Hcy水平。结果:(1)对照组及病例组T/T纯合子率分别为37.5％和22.5％;T等位基因频率分别为60.9％和51.3％,差异均无显著统计意义(均P>0.05)。(2)病例组血浆Hcy几何均值(11.0±2.3μmol/L)显著高于对照组(8.0±1.4μmol/L,P<0.05)。(3)所有受试者中T/T组Hcy值高于C/C组(10.4μmol/L和7.6μmol/L),但差异无显著性(P>0.05)。结合叶酸考虑,进一步将所有受试者按叶酸中位数水平分组。叶酸中位数以下组中,T/T组Hcy值显著高于C/C组(P<0.05);而叶酸中位数以上组中,T/T组Hcy值与C/C组无显著差异。(4)血浆Hcy与叶酸、维生素B12呈显著负相关,与肌酐呈显著正相关。吸烟者血浆Hcy水平显著高于不吸烟者(P<0.05)。结论:(1)本组人群MTHFR基因C677T突变的纯合子在低叶酸状态下可引起血浆Hcy水平显著增高,但与青年脑血管病无显著关系。MTHFR基因677TT纯合突变可能为健康青年人脑血管的保护因素。(2)血浆Hcy水平与青年脑血管病的发生密切相关。(3)叶酸、维生素B12肌酐、吸烟是Hcy的非遗传影响因素。     

MTHFR基因C677T位点突变及高同型半胱氨酸血症和血管性痴呆的发生相关性

目的研究血浆同型半胱氨酸(Hcy)浓度及亚甲基四氢叶酸还原酶(MTHFR)基因多态性与血管性痴呆(VaD)的关系。方法选取83例VaD患者作为观察组和81例非痴呆脑梗死患者作为对照组,分别测定两组患者的MTHFR基因多态性、Hcy浓度、维生素B12和叶酸水平,根据简易精神状态检查量表(MMSE)评定VaD患者痴呆程度,对指标进行比较和相关性分析。结果 MTHFR基因TT纯合子在观察组VaD患者的分布频率明显高于对照组,差异具有统计学意义(P0.05);两组患者的MTHFR基因C、T等位基因分布频率差异具有统计学意义(P0.05)。观察组VaD患者的血浆Hcy浓度明显高于对照组,其血清叶酸与维生素B12浓度明显低于对照组,VaD患者的血浆Hcy水平随着痴呆程度的增加而明显提高,差异均具有统计学意义(P0.05)。VaD患者血浆Hcy水平与自身痴呆程度呈正相关(r=0.452,P0.05),与MMSE评分呈负相关(r=-0.246,P0.05)。结论MTHFR基因C677T突变及高水平Hcy与VaD的发生、发展相关,高Hcy血症是VaD发病的一个重要因素。     

血浆同型半胱氨酸及MTHFR多态性与动脉粥样硬化性血栓性脑梗死

目的 探讨血浆同型半胱氨酸(HCY)及N~(5,10)-亚甲基四氢叶酸还原酶(MTHFR)基因多态性与脑血栓形成的关系。方法 应用高效液相色谱-荧光法(HPLC-FD)和聚合酶链(PCR)限制性内切酶片段长度多态性分析检测87例急性脑血栓形成患者和80例对照者血浆HCY浓度和MTHFR基因型。结果 病例组空腹血浆HCY浓度(15.28±4.33umol/L)较对照组(11.32±3.86umol/L)高(P<0.001);MTHFR纯合子血浆HCY浓度(20.41±3.74umol/L)较杂合子(14.13±4.50umol/L)和野生型(12.57±4.19umol/L)高(P=0.001 and P<0.001);两组纯合子突变率分别为4.60％和3.75％(P=0.910)。结论 MTHFR突变致高HCY血症,高HCY血症而非MTH-FR突变是脑血栓形成的独立危险因素。     

高同型半胱氨酸血症及相关因子与脑梗死相关性的研究

目的 :研究高同型半胱氨酸血症及N5N10 亚甲基四氢叶酸还原酶 (methylenetetrahydrofolatereductase ,MTHFR)基因、叶酸和维生素B12 与脑梗死的关系。方法 :PCR RFLP技术检测 5 4例脑梗死患者及 3 0例对照的MTHFR基因型 ;高效液相色谱法测定空腹及蛋氨酸负荷后血浆tHcy水平 ;化学发光法测定血清叶酸和维生素B12 浓度。结果 :患者组中MTHFR基因T/T型及T等位基因频率、空腹及负荷后tHcy水平显著高于对照组 ;而血清叶酸和维生素B12 水平低于对照组。结论 :MTHFR基于突变、高同型半胱氨酸血症及叶酸、维生素B12 缺乏与脑卒中发病有关。     

脑梗死患者血清同型半胱氨酸变化及机制的探讨

目的　探讨血清同型半胱氨酸 (Homocysteine,HCY)及其代谢相关因子和血脂与脑梗死的关系 ,并观察叶酸、维生素 B6 对 HCY的影响。方法　对 5 9例经 CT或 MRI证实为脑梗死的患者和 2 9例健康对照者 ,采用高效液相色谱法测定血清同型半胱氨酸水平 ,并应用 PCR扩增法检测 CBS基因 T833C多态性。结果　 (1)脑梗死患者血清 HCY浓度 (2 3.0 0± 7.4 6 nmol/ m l)显著高于正常对照组 (12 .4 6± 3.6 0 nmol/ m l) ,两组比较差异显著 (t=8.94 1,P<0 .0 0 1)。 (2 ) CBS基因在患者组发现 7例纯合子突变 ,2 5例杂合子突变 ;对照组 2例纯合子突变 ,3例杂合子突变 ,两组基因型和等位基因频率分布差异有显著意义 ,前者χ2 =11.32 9,P<0 .0 1;后者χ2 =8.86 8,P <0 .0 1。 CBS基因杂合突变者血清 HCY浓度显著高于正常基因者 t=4 .5 6 9,P<0 .0 0 1。 (3)脑梗死患者血脂与 HCY水平无明显相关。 (4)叶酸、维生素 B6 治疗后 ,CBS正常基因型血 HCY下降最为显著。结论　高同型半胱氨酸血症是脑梗死的独立危险因素 ,而 CBS基因 T833C突变及维生素 B6 、叶酸缺乏可能是其增高的重要因素     

脑血管病患者血浆同型半胱氨酸水平及MTHFR基因多态性分析

目的探讨血浆同型半胱氨酸(homocysteine Hcy)水平与脑血管病的关系及其水平升高的遗传和营养因素.方法对130例脑梗死和77例脑出血患者及65例正常对照者采用高效液相色谱(HPLC)法检测血浆Hcy水平、放射免疫法测定叶酸、VitB12水平,运用多聚酶链反应-限制性内切酶片段长度多态性技术(PCR-RFLP)分析亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase MTHFR)基因多态性,并加以对照分析.结果脑梗死组、脑出血组血浆Hcy水平分别为19.87±11.67 μmol/L、20.15±10.12 μmol/L,均显著高于对照组11.41±3.28 μmol/L(P<0.01);而脑梗死组与脑出血组间无显著差异(P>0.05).MTHFR有三种基因型,脑梗死组、脑出血组和对照组C/C型基因频率分别为0.39、0.46、0.53,C/T型分别为0.35、0.31、0.30,T/T型分别为0.26、0.23、0.17,T等位基因频率分别为0.43、0.39、0.32,各基因型及等位基因频率无显著差异(P>0.05).各组中T/T基因型血浆Hcy水平与C/C型比较差异有显著性(P<0.01),而病例组中C/T型血浆Hcy水平与C/C型相比亦有显著差异(P<0.01).脑梗死组与脑出血组叶酸、VitB12水平显著低于正常对照组(P<0.01).结论血浆Hcy水平升高是脑血管病的主要危险因素.MTHFR基因677位点碱基C→T突变可能是血浆Hcy水平升高的主要影响因素,但与脑血管病的直接关系有待进一步研究,而叶酸 VitB12与Hcy水平也有关联.     

血浆同型半胱氨酸水平及MTHFR基因多态性与中青年脑卒中的相关研究

目的探讨中青年脑卒中与血浆同型半胱氨酸(homocysteine Hcy)水平及亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase MTHFR)基因多态性的关系.方法利用多聚酶链反应-限制性内切酶片段长度多态性技术(PCR-PFLP)分析73例中青年脑卒中患者及134例老年脑卒中患者与27例中青年及38例老年正常对照人群MTHFR基因突变情况,并应用高效液相色谱(HPLC)法检测其血浆Hcy水平、放射免疫法测定叶酸、VitB2水平加以对照分析.结果中青年脑卒中组血浆Hcy水平(22.36±10.99μmol/L)及老年脑卒中组血浆Hcy水平(19.41±10.32μmol/L)均高于各自对照组(11.49±5.05μmol/L)及(12.26±5.24μmol/L),差异有显著性(P＜0.01),且中青年脑卒中组中血浆Hcy升高的比例(58%)显著高于老年脑卒中组(43%)(x2=4.69,P＜0.05).MTHFR有三种基因型,中青年脑卒中组及对照组C/C型C/T型T/T型分别为(0.25、0.44、0.31)及(0.52、0.32、0.16),两组相比差异有显著性(x2=8.51,P＜0.05);而老年脑卒中组及对照组分别为(0.35、0.46、0.19)及(0.52、0.32、0.16),两组相比无显著差异(x2=3.96,P＞0.05).各组MTHFR的T/T基因型血浆Hcy水平与C/C型比较有显著差异(P＜0.01),两脑卒中组MTHFR的C/T基因型血浆Hcy水平与C/C型比较也有显著差异(P＜0.05),且叶酸VitB12水平较各自对照组显著下降(P＜0.01),老年脑卒中组较中青年组叶酸水平降低更显著(P＜0.05).结论血浆Hcy水平升高是脑血管病的重要危险因索,MTHFR基因突变及叶酸VitB12变化均是血浆Hcy升高的重要影响因素,对于中青年患者意义更大.     

轻度认知功能障碍与血浆同型半胱氨酸水平的相关性研究

目的 探讨轻度认知功能障碍(MCI)与血浆同型半胱氨酸、维生素B12、叶酸水平的关系.方法 68例MCI患者测定血浆同型半胱氨酸、维生素B12、叶酸水平及简易精神量表评分等,并与70例健康老人作对照.结果 MCI患者血浆HCY明显高于对照组,而维生素B12、叶酸水平明显低于对照组(均P＜0.05);在轻度认知功能障碍组,当患者血浆HCY＞15umol/l时,其轻度认知功能障碍的优势比OR值为4.3,95%CI为1.89～7.43. MCI 患者HCY水平与维生素B12、叶酸水平及评分均称负相关关系.结论 血浆HCY升高是MCI的重要因素,体内叶酸、维生素B12缺乏是导致血浆HCY升高的原因.     

Gene--nutrition interactions in coronary artery disease: correlation between the MTHFR C677T polymorphism and folate and homocysteine status in a Korean population

INTRODUCTION: Elevated plasma total homocysteine is a major risk for coronary artery disease (CAD). Methyltetrahydrofolate reductase (MTHFR) is a main regulatory enzyme in homocysteine metabolism; a common C677T mutation in the MTHFR gene results in decreased enzyme activity, and contributes to increased homocysteine levels and decreased folate levels. We investigated the frequency of MTHFR C677T alleles in a Korean population, determined the genotype-specific threshold levels of folate or vitamin B12, and investigated the relationship between the TT genotype and the risk of CAD. MATERIALS AND METHODS: We enrolled a study population of 163 CAD patients and 50 control subjects, and screened the MTHFR C677T polymorphism using real-time PCR with melting point analysis. Levels of plasma homocysteine, folate and vitamin B12 were also determined. We then defined the genotype-specific threshold values of folate and vitamin B12 required to keep homocysteine levels in a normal range for individuals of each MTHFR C677T genotype. RESULTS: The frequency of the TT genotype was 18% in control subjects and 26% in patients group (P>0.05). Individuals homozygous for the TT genotype had significantly elevated homocysteine levels (P<0.05). The genotype-specific folate threshold level was significantly higher in TT individuals than in the CC or CT genotypes. The OR of individuals with low folate status and the TT genotype to estimate the relative risk of CAD was 2.2 and the OR of those with high folate status and the TT genotype was 1.5 (95% CI, 0.5-9.6 and 0.7-3.2, respectively). CONCLUSION: We were able to define a gene-nutrient interaction that shows a higher risk for CAD based on specific threshold folate levels required by different MTHFR C677T genotypes in a Korean population.     

轻度认知障碍患者血浆同型半胱氨酸和血清维生素B12及叶酸水平变化研究

目的 探讨轻度认知障碍(MCI)患者血浆同型半胱氨酸(Hcy)、血清维生素B12及叶酸水平的变化及相互关系.方法 MCI组80例,正常对照组80例,检测所有观察对象的血浆同型半胱氨酸、血清VitB12及叶酸水平并分析相互关系.结果 MCI组血浆Hey水平较正常组显著增高为(18.9±8.8)μmol/L vs(14.35±5.7)μmol/L,而血清叶酸和VitB12水平在正常组和MCI组之间并没有显著差异;相对于血浆Hey正常组,MCI比值比(0R)在轻、中度高同型半胱氨酸血症组中增高(OR=1.85,95%CI=1.56～2.95;OR=3.32,95%CI=1.61～6.48;P=0.001);无论在MCI组还是在正常组中,血浆Hey与血清叶酸及Vit B12的水平均呈负相关.结论 血浆Hey水平升高与MCI相关,叶酸和VitB122缺乏可能导致血浆Hcy水平升高.     

Homozygous thermolabile methylenetetrahydrofolate reductase in schizophrenia-like psychosis

Summary The gene for methylenetetrahydrofolate reductase (MTHFR) has shown polymorphism in the general human population. In its homozygous form, a C677T mutation occurs in more than 5% of the grown-up population and produces a thermolabile variant which reduces the overall enzyme activity to less than 30% of normal. We investigated patients with schizophrenia-like psychosis. If hyperhomocysteinemic, their DNA-genotype for thermolabile C677T mutation was determined. Seven of 11 patients, six males and one female, were homozygous for thermolabile MTHFR. One male patient was heterozygous and all three normal homozygotes were females. In the patients who were homozygous for the C677T mutation, the homocysteine concentrations did not respond to vitamin B12 but were normalized by folate supplementation. In the normal homozygotes, however, the homocysteine concentrations were reduced by vitamin B12 alone. Our results suggest that homozygosity for thermolabile MTHFR is a risk factor for schizophrenia-like psychosis. Possibly, this risk may be reduced by folate supplementation.     

The role of vitamin B12 in fasting hyperhomocysteinemia and its interaction with the homozygous C677T mutation of the methylenetetrahydrofolate reductase (MTHFR) gene. A case-control study of patients with early-onset thrombotic events

Total fasting plasma homocysteine (tHcy), homozygosity for the C677T mutation of the methylenetetrahydrofolate reductase (MTHFR) gene and for the A2756G mutation of the methionine synthase (MS) gene, vitamin B12 and folate plasma levels were evaluated in 170 consecutive patients (89 M, 81 F; mean age 41 +/- 12 yrs) with documented early-onset thrombosis (89 venous, 69 arterial, 12 both; mean age at first episode 36 +/- 11 yrs), and in 182 age- and sex-matched healthy control subjects. Moderate hyperhomocysteinemia (HHcy, tHcy >19.5 microM in men and >15 microM in women) was detected in 45 patients (26.5%) and in 18 controls (9.9%, Mantel-Haenszel OR and 95% C.I. after stratification for arterial or venous thrombosis: 3.25, 1.78-5.91). The 677TT MTHFR genotype was not significantly more prevalent in patients (27.6%) than in controls (21.4%, RR = 1.42: 0.84-2.41), and markedly contributed to HHcy (Mantel-Haenszel RR after stratification for case/control status: 8.29, 4.61-14.9). The 2756GG MS genotype, observed in 4 patients (2.4%) and 8 controls (4.4%), was not associated to HHcy. tHcy was negatively correlated to folate and vitamin B12 levels, with better correlation found in subjects with the 677TT mutation (r = -0.42 and -0.25) than with the 677CC or CT MTHFR genotype (r = 0).37 and -0.11). However, folate was similar in patients and controls and vitamin B12 was higher in patients (460 +/- 206 vs. 408 +/-185 pg/ml, p = 0.011). In a generalized linear model, 44% of the variation in tHcy levels was explained by folate and vitamin B12 levels, the MTHFR genotype, gender, and by the interaction of the MTHFR genotype with folate (p < or =0.028); the interactions of vitamin B12 with the MTHFR genotype, gender and patient/control status also significantly contributed to the variation in tHcy levels (p < or =0.028). A 4-week administration of 5-methyltetrahydrofolate (15 mg/day) markedly lowered plasma tHcy in 24 patients with MTHFR 677TT genotype, but the response to treatment correlated with vitamin B,2 levels (p = 0.023). Subjects carrying the MTHFR 677TT genotype have higher folate and vitamin B12 requirements irrespective of the A2756G polymorphism of the MS gene. Yet unidentified abnormalities of MS or of any of the enzymes participating in the synthesis of methylated vitamin B12 may play an important role in the phenotypic expression of moderate hyperhomocysteinemia.     

Intergenotypic variation of Vitamin B12 and Folate in AD: In north indian population

Objectives:

Changes in lifestyle habits such as diet modification or supplementation have been indicated as probable protective factors for a number of chronic conditions including Alzheimer''s disease (AD). With this background, we aim to hypothesize that whether C677T polymorphism of methylenetetrahydrofolate reductase (MTHFR) gene contributes towards the risk of developing AD and its association with vitamin B12 and folate levels.

Materials and Methods:

A case-control study comprising of total 200 subjects, within the age group of 50-85 years. Their blood samples were analyzed for serum folate, vitamin B12 levels, and MTHFR C677T polymorphism by restriction fragment length polymorphism (RFLP).

Results:

The mean plasma levels of vitamin B12 and folate were significantly lower in study group when compared to the control group (P < 0.001). Genotypic and allelic frequency of MTHFR gene in both groups was found to be significant (P < 0.05). The intergenotypic variations of vitamin B12 and folate were found to be significant (P < 0.001).

Conclusion:

We concluded that the subjects with homozygous mutated alleles are more prone to AD and also pointed out the influence of presence/absence of MTHFR T allelic variants on serum folate and vitamin B12 levels.     

Methylenetetrahydrofolate reductase gene polymorphisms in patients with cerebral hemorrhage

Elevated plasma total homocysteine (HCY) level is a risk factor for coronary heart disease and ischemic stroke. We investigated relationships between polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, and plasma levels of HCY and folate in patients of Mongolian races who suffered from cerebral ischemia (CI, n = 42) or cerebral hemorrhage (CH, n = 20) and in the 24 age-matched controls. The incidences of both homozygous and heterozygous MTHFR gene mutations in CI (26 and 43%) and in CH (25 and 60%) were significantly higher than those in the controls (8 and 25%). Homozygous MTHFR gene mutation was associated with reduced plasma folate levels, but not with increased plasma HCY levels. Among the subjects with homozygous MTHFR gene mutation, plasma folate levels in CH was significantly lower than those in CI and controls. MTHFR gene mutation in CH was found to be as common as that in CI and was associated with reduced plasma folate levels in the both. In homozygous MTHFR gene mutation, the plasma folate level was profoundly reduced in CH as compared with CI and controls, suggesting that subjects with low plasma folate levels have a predisposition to intracerebral bleeding.     

Homocysteine,apolipoproteine E and methylenetetrahydrofolate reductase in Alzheimer's disease and mild cognitive impairment

BACKGROUND: Alzheimer's disease (AD) is the most common dementia disorder in elderly people. Currently, the only known genetic factor associated with the development of sporadic AD is the apolipoprotein E (ApoE) 4 allele. There is a need to identify other environmental and genetic risk factors that could modulate the risk of developing sporadic AD. OBJECTIVE: To analyse the correlation between the ApoE and methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism and plasma homocysteine levels and vitamins (B(12) and folic acid) concentrations in serum from patients with AD and mild cognitive impairment (MCI) as compared with control group. METHODS: The study was carried out in 99 AD patients, 98 subjects with MCI and 100 healthy subjects. Diagnosis of probable AD was made according to the NINCDS-ADRDA and DSM-IV criteria. The following factors were analysed: age, gender, duration of disease, concentration of plasma total homocysteine, folic acid and vitamin B(12) in the serum and the polymorphism of MTHRF and ApoE genes. The results obtained were analysed by multivariate analysis of regression. RESULTS: We found that plasma total homocysteine is increased in AD patients (p < 0.0001) and depended on the MTHFR T/T genotype in the presence of low folate levels (p < 0.05). The increased frequency of ApoE4 allele in the AD population was independent of homocysteine, folic acid and vitamin B(12) levels and MTHFR status. CONCLUSIONS: We conclude that the concentration of plasma total homocysteine is increased in AD patients. This may be associated with the T/T genotype in the MTHFR gene; however, the distribution of the MTHRF C677T polymorphism in the Polish population does not differ in AD and controls.