长治老年人群血浆同型半胱氨酸水平与MTHFRC677T基因多态性

目的探讨长治地区健康老年人群血浆同型半胱氨酸(HCY)水平与N5,N10-亚甲基四氢叶酸还原酶(MTHFR)C677T基因位点的基因多态性。方法采用酶联免疫吸附法进行血浆HCY水平测定;采用聚合酶链反应-限制性片段长度多态性法(PCR-RFLP)对MTHFR C677T进行基因多态性分析。结果长治地区健康老年人群血浆HCY水平为(11.0±3.1)μmol/L,与健康青年人群相比,无统计学差异(P0.05)。老年人群中MTHFR C677T基因的CC、CT和TT基因型频率分别为15.38%、48.72%和35.90%,与青年人群相比,两者差异无统计学性(P0.05);老年人群C、T等位基因频率分别为39.74%和60.26%,与青年人群相比,两者差异无统计学意义(P0.05)。MTHFR C677T基因型频率在长治地区健康老年人群、青年人群中均符合Hardy-Weinberg平衡。健康老年人群MTHFR C677T位点各基因型间,血浆HCY水平亦无显著差异。健康老年人群、青年人群TT基因型血浆HCY水平差异显著(P0.05)。结论长治人群MTHFR C677T纯合突变基因型频率高,且老年人群TT基因型血浆HCY水平显著高于青年人群。     

血管性痴呆患者与其血浆同型半胱氨酸水平的关系

目的 探讨血管性痴呆(VD)患者与其血浆同型半胱氨酸水平的关系.方法 用高效液相色谱仪和电化学检测法测定1998年2月至2000年2月收治的37例VD患者的血浆总同型半胱氨酸水平,并与40名正常同龄对照组及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N5,N10-亚甲基四氢叶酸还原酶(MTHFR)基因多态性,同时测定血浆叶酸及维生素B12水平.结果 VD患者血浆总同型半胱氨酸水平显著高于正常同龄对照组和非痴呆脑梗死组;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.3组基因型和等位基因频率相比,差异均无显著性;VD组血浆叶酸及维生素B12水平明显低于正常同龄对照组和非痴呆脑梗死组(P＜0.05).结论 高同型半胱氨酸血症可能是VD发病的一个新的危险因素.     

N5,N10-亚甲四氢叶酸还原酶基因多态性及血浆同型半胱氨酸水平与心肌梗死的关系

研究N^5,N^10-亚甲四氢叶酸还原酶基因多态性及血浆同型半胱氨酸水平与心肌梗死的关系。运用多聚酶链反应-限制片长多态性技术检测178例心肌梗死患者及178例正常人N^5,N^10-亚甲四氢叶酸还原酶基因多态性，用高效液相色谱仪和荧光检测仪测定血浆总同型半胱氨酸水平。结果发现，N^5,N^10-亚甲四氢叶酸还原酶有3种基因型，即纯合子突变型（TT），杂合子突变型（TC）及正常型（CC），心肌梗死组TT型频率为35.4%，TC型频率为53.8%。CC型频率为10.8%。T等位基因频率为62.3%。C等位基因频率为37.7%，正常组中TT型频率为20.1%。TC型频率为55.8%。CC型频率为24.1%。T等位基因频率为32.1%,C等位基因频率为67.9%，且心梗死组TT高于正常组。正常人群中TT基因型者血浆总同型半胱氨酸水平明显高明于（TC CC）基因型者，心肌梗死患者血浆总同型半胱氨酸水平显著高于正常组，多因素分析显示，N^5,N^10-亚甲四氢叶酸还原酶基因突变型TT可能是心肌梗死发病一个危险因素，结论提示，N^5,N^10-亚甲四氢叶酸还原酶TT基因型突变可能升高个体血浆总同型半胱氨酸水平，N^5,N^10-亚甲四氢叶酸还原酶基因可能是心肌梗死的易感基因之一，N^5,N^10-亚甲四氢叶酸还原酶基因突变型TT及高同型半胱氨酸血症可能是心肌梗死发病的一个危险因素。     

脑梗死患者颈动脉斑块与血浆同型半胱氨酸水平及亚甲基四氢叶酸还原酶基因多态性的关系

目的探讨血浆同型半胱氨酸水平、亚甲基四氢叶酸还原酶(MTHFR)基因多态性与脑梗死患者颈动脉斑块之间的关系。方法选择颈动脉系统急性脑梗死患者128例,采用荧光偏振免疫法测定血浆同型半胱氨酸水平,聚合酶链反应-限制性片长多态性技术检测MTHFR基因多态性。应用彩色超声心动仪进行颈动脉超声检查,根据超声结果将患者分为颈动脉粥样硬化斑块组(简称斑块组)和无斑块组,比较两组血浆同型半胱氨酸水平及MTHFR基因多态性。结果斑块组TT基因型(35.8%比17.0%)及T等位基因频率(58.6%比40.4%)均显著高于无斑块组(P<0.05)。斑块组血浆同型半胱氨酸水平显著高于无斑块组(22.42±11.04μmol/L比17.89±5.96μmol/L,P<0.05)。各组内MTHFR 677TT纯合子同型半胱氨酸水平均显著高于CT型和CC型者(P<0.05)。Logistic回归分析表明,校正性别、年龄、高血压、糖尿病、高脂血症、吸烟、饮酒等危险因素后,血浆同型半胱氨酸水平仍为颈动脉粥样硬化斑块的独立危险因素[OR 1.160(95%CI 1.034～1.301),P<0.05]。结论血浆同型半胱氨酸水平升高是脑梗死患...     

慢性肾衰竭血透患者N5, N10-亚甲基四氢叶酸还原酶基因多态性和血浆同型半胱氨酸水平的研究

目的研究血透患者N5, N10-亚甲基四氢叶酸还原酶(MTHFR)基因多态性及血清叶酸、维生素B12 (Vit B12)水平与血浆总同型半胱氨酸(tHcy)的关系.方法运用聚合酶链反应-限制性内切酶片断长度多态性技术(PCR-RFLP),检测53例血透患者(HD组)及40例健康对照组(C组)的MTHFR基因多态性;用高效液相色谱法和荧光探测仪测定血浆tHcy水平;用免疫化学发光法测定血清叶酸、Vit B12水平.结果 (1)MTHFR基因型有3种,纯合子突变型(+/+)、杂合子突变型(+/-)、正常型(-/-).HD组中(+/+)型频率为30.2 %,(+/-)型频率为45.3%,(-/-)型频率为24.5%,T等位基因频率为52.8%,基因型分布和等位基因频率与C组比较差异无显著性.(2)HD组中98%的患者存在着高Hcy (＞15.0 μmol/L)血症,平均血浆 tHcy 水平显著高于C组(38.68 μmol/L 对15.47 μmol/L,P<0.01).(3)HD组中(+/+)型平均血浆tHcy水平高于(-/-)型(45.32 μmol/L 对28.44 μmol/L),两者差异具有显著性(P=0.038).(4)HD组血清叶酸、Vit B12均与血浆tHcy水平呈负相关(r=-0.377,P=0.005;r=-0.311,P=0.023).结论血透患者血浆tHcy水平升高不仅与患者尿毒症时对其清除及代谢障碍有关,还受到MTHFR基因多态性和叶酸、Vit B12水平的影响.     

MTHFR基因多肽性及血浆同型半胱氨酸水平与老年人脑卒中发病的关系

目的：探讨N^5，N^10-亚甲基四氢叶酸还原酶（MTHFR）基因C677T位点突变和血浆总同型半胱氨酸（tHcy）水平升高是否增加中国老年人群脑卒中的危险。方法：对1002例经头颅CT确诊的老年（〉60岁）脑卒中患者和948例非卒中对照者，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MTHFR C667T基因型，用高效液相色谱法测定血浆总同型半胱氨酸水平，同时所有研究对象记录其病史，体检等临床资料及吸烟，饮酒等流行病学资料。结果：脑卒中患者MTHFR基因纯合子突变（TT）和杂合子突变（CT）发生率（69．4％）明显高于对照组（64．3％，P=0．016），卒中组T等位基因频率（45．8％）也高于对照组（42．4％，P=0．032）；脑卒中患者血浆总同型半胱氨酸水平及异常检出率和中、重度增高率亦明显高于对照组（P〈0．001），且MTHFR基因TT型〉CT型〉CC型（P〈0．001）。Logistic回归分析结果显示：在调整传统危险因素后，升高的tHey水平和CT和TT基因型仍与脑卒中发病的有关，且血浆同型半胱氨酸水平越高发生脑卒中的危险性越大。结论：高同型半胱氨酸血症是中国老年人脑卒中发病的一个独立危险因素，而MTHFR基因C677T位点突变可能是其发病的重要遗传因素。     

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。     

血浆同型半胱氨酸水平亚甲基四氢叶酸还原酶基因多态性与强直性脊柱炎的相关性研究

目的 探讨血浆同型半胱氨酸(Hcy)水平与强直性脊柱炎(AS)间的联系,分析AS患者MTHFR基因C677T突变的多态性,并探讨MTHFR基因多态性与AS的相关性.方法 运用酶联免疫吸附试验(ELISA)测定100例AS患者及60名健康志愿者血浆Hcy浓度,应用多聚酶链反应-限制性内切酶片段长度多态性(PCR-RELP)分析MTHFR基因的多态性.结果 AS患者血浆Hcy浓度明显高于对照组,两组间差异有统计学意义(P＜0.01);AS组T/T型、C/T型、C/C型基因频率分布及T、C等位基因频率与对照组比较差异无统计学意义(P＞0.05);AS组T/T基因型突变的比例与对照组比较差异有统计学意义(P＜0.05);AS组和对照组T/T型的血浆Hcy水平明显高于C/T型和C/C型(P＜0.01).Logistic回归分析显示高Hcy血症是AS发病的独立危险凶素(P＜0.01,OR=4.582,95%CI=1.984～10.585).结论 AS患者血浆Hcy浓度明显高于健康志愿者,高Hcy血症是AS发病的独立危险因素.MTHFR基因T/T型突变是血浆Hcy浓度升高的一个重要影响机制,MTHFR基因T/T型突变可能与AS的发生有相关性.     

动脉粥样硬化性脑梗死患者血浆同型半胱氨酸水平及亚甲基四氢叶酸还原酶基因多态性

目的 探讨血浆同型半胱氨酸水平、亚甲基四氢叶酸还原酶基因多态性与动脉粥样硬化性脑梗死之间的关系.方法 选择性别、年龄匹配的动脉粥样硬化性脑梗死患者(脑梗死组)68例及对照组50例,采用荧光偏振免疫法测定血浆同型半胱氨酸水平,聚合酶链反应-限制性片长多态性技术检测亚甲基四氢叶酸还原酶基因多态性.结果 脑梗死组TT基因型(36.8%比16.0%)及T等位基因频率(59.6%比38.0%)均显著高于对照组(P<0.05).脑梗死组血浆同型半胱氨酸水平显著高于对照组(P<0.05).脑梗死组和对照组亚甲基四氢叶酸还原酶 677TT纯合子血浆同型半胱氨酸水平均显著高于CT型和CC型者(P<0.05).结论 血浆同型半胱氨酸水平升高是动脉粥样硬化性脑梗死的危险因素.亚甲基四氢叶酸还原酶 C677T基因多态性与血浆同型半胱氨酸水平密切相关,与动脉粥样硬化性脑梗死显著相关.     

老年人亚甲基四氢叶酸还原酶、蛋氨酸合成酶基因多态性及同型半胱氨酸水平与冠心病的关系

目的探讨老年人同型半胱氨酸(Hcy)水平与冠心病的关系,并对亚甲基四氢叶酸还原酶(MTHFR)A1298C基因多态性、蛋氨酸合成酶(MS)A2756G基因多态性与Hcy水平及冠心病的关系进行探讨. 方法 177例老年人为研究对象,其中129例冠状动脉造影证实为冠心病患者(冠心病组),48例冠状动脉造影完全正常(对照组).荧光偏振免疫分析法测定Hcy水平,聚合酶链反应-限制性片段长度多态性方法(PCR-RFLP)分析MTHFR A1298C、MS A2756G基因多态性. 结果冠心病组血Hcy水平显著高于对照组[(16.2±8.6)对(12.7±5.0)μmol/L,P<0.01].MTHFR A1298C基因多态性CC纯合子和AC杂合子血Hcy水平均显著低于AA野生型[(9.1±2.5)、(13.5±6.6)对(16.0±8.3)μmol/L,P<0.01],CC纯合子和AC杂合子间血Hcy水平差异无显著性(P>0.05);MTHFR 1298CC纯合子在冠心病组的分布频率显著低于对照组(3.1%对14.6%,P<0.05).MS A2756G基因多态性GG+AG基因型血Hcy水平显著低于AA野生型[(12.8±6.5)对(15.6±8.1)μmol/L,P<0.05],MS 2756GG+AG基因型在冠心病组的分布频率显著低于对照组(9.3%对20.8%,P<0.05). 结论本研究入选的老年人群中,冠心病患者血Hcy水平升高.MTHFR 1298CC基因型及MS 2756 GG +AG基因型与低血Hcy水平相关,它们可能会通过降低血Hcy水平而减少老年人冠心病的发生.     

Methylenetetrahydrofolate reductase mutation (677C-->T) negatively influences plasma homocysteine response to marginal folate intake in elderly women

Individuals who are homozygous for the methylenetetrahydrofolate reductase (MTHFR) 677C --> T mutation have depressed serum folate (SF) and elevated plasma total homocysteine (tHcy) concentrations, which may affect folate requirements and increase the risk for coronary artery disease. A controlled metabolic study (14 weeks) using a depletion/repletion protocol was performed in women (aged 60 to 85 years, N = 33) to provide age-specific data on the effects of the MTHFR mutation on SF and tHcy status. Subjects consumed a moderately folate-deplete diet (118 microg/d) for 7 weeks, followed by 7 weeks of folate repletion with 200 or 415 microg/d provided as two different treatments. Following folate depletion, the mean SF concentration was lower for homozygous (P = .017) versus heterozygous subjects. Homozygotes for the 677C --> T mutation showed a higher (P = .015) percent increase in plasma tHcy (44%) than heterozygous (20%) or normal (15%) subjects. At week 7, the mean plasma tHcy concentration was higher in homozygous subjects (12.5 +/- 5.3 micromol/L, mean +/- SD) versus the heterozygous (10.8 +/- 3.8 micromol/L, P = .008) or normal (11.3 +/- 2.7 micromol/L, P = .001) genotype groups. Following folate repletion, plasma tHcy concentrations were not different between genotype groups, despite a higher (P < .016) SF concentration in subjects with the homozygous genotype. These data suggest that older women who are homozygous for the MTHFR 677C --> T mutation may be at risk for greater elevations in plasma tHcy in response to moderately low folate intake as compared with individuals with the normal or heterozygous genotypes.     

Hyperhomocysteinemia and the MTHFR C677T mutation in Budd-Chiari syndrome

Hyperhomocysteinemia (HH) is a factor that predisposes individuals to thrombosis, and the C677T mutation in the 5,10-methylenetetrahydrofolate reductase (MTHFR) is known to give increased plasma homocysteine. However, little is known about their roles in Budd-Chiari syndrome (BCS). This study evaluated the roles of HH and the MTHFR C677T mutation in patients with BCS. We compared 41 BCS patients with 80 sex- and age-matched healthy controls. The mean plasma homocysteine level was significantly higher in patients with BCS (20.15 +/- 5.78 micromol/L) compared with normal controls (15.80 +/- 6.58 micromol/L), P < 0.01. HH (>19.5 micromol/L in men and >15.0 micromol/L in women) was detected in 15 (36.59%) patients and in 14 (17.5%) controls (odds ratio [OR], 2.72; 95% confidence internal [CI], 1.17-6.32). The prevalence of the mutated MTHFR 677TT genotype and the 677T allele in normal controls was 10.0% and 31.3%, respectively. The mutant 677T homozygotes and alleles were more frequent in patients with BCS than in controls (22.0% vs. 10.0%, 0.025 < P < 0.05; 45.1% vs. 31.3%, 0.025 < P < 0.05). The relative risk of BCS among the carriers of 677TT was significantly increased (OR, 3.3; 95% CI, 1.1-10.0). The mutant MTHFR heterozygous 677C/T carriers were not significantly increased in patients with BCS compared with controls (46.3% vs. < 2.5%, P > 0.05). The relative risk OR of BCS among carriers of 677C/T was 1.6 (95% CI, 0.7-3.6). This study suggests that both HH and the homozygous C677T mutation in the MTHFR gene are important risk factors of BCS.     

The graded effect of hyperhomocysteinemia on the severity and extent of coronary atherosclerosis

It is not clear to what extent methylenetetrahydrofolate reductase (MTHFR) gene and hyperhomocysteinemia effect the severity and extent of coronary atherosclerosis in Asian populations. We examined the MTHFR genotypes and plasma homocysteine (HCY) concentrations in 192 Taiwanese and investigated their relationship with coronary artery disease (CAD), and the severity and extent of coronary atherosclerosis. The distribution of MTHFR genotypes was similar in 116 CAD patients and 76 non-CAD subjects. Homozygosity was noted in 8% of CAD patients and 13% of non-CAD subjects (P=0.33; 95% CI, 0. 2-1.6). The geometric mean of HCY values was higher in CAD patients (11.10+/-1.51 micromol/l) than in non-CAD subjects (9.21+/-1.55 micromol/l) (P=0.003). HCY levels were higher in patients with multi-vessel disease (P<0.05) or in patients with > or = 90% stenotic lesions (P=0.005), compared with non-CAD subjects. The CAD risks in the top two HCY quartiles (> or = 14.0 and 10.1-13.9 micromol/l) were 4.0 (95% CI, 1.7-9.2) and 3.2 (95% CI, 1.4-7.4) times higher than in the lowest quartile (< or = 7.9 micromol/l) (P=0.001 and 0.007, respectively). Linear regression analysis showed significant correlations between HCY concentrations and the severity and extent of atherosclerosis (P=0.0001 for both). In conclusion, hyperhomocysteinemia appears to have a graded effect on the risk of CAD as well as the severity and extent of coronary atherosclerosis. Our findings do not support the homozygous genotype of MTHFR as a genetic risk factor for CAD in this Taiwanese population. Perhaps a further study including assessment of vitamin status is needed to better clarify the relationship between MTHFR genotypes and CAD.     

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.     

风湿性疾病中高同型半胱氨酸血症的临床研究

目的　分析多种风湿性疾病患者血浆中同型半胱氨酸(Hcy)水平及其相关因素。方法脊柱关节病(uSpA)患者和 62例正常对照的Hcy、VitB12、叶酸的水平和亚甲基四氢叶酸还原酶(MTHFR)基因 677位的多态性。结果　(1)各疾病组Hcy水平分别为:SLE组 (19 04±6 86)μmol/L,RA组(19 07±7 43)μmol/L,AS组(16 47±6 50)μmol/L,uSpA组(16 59±6 72)μmol/L,对照组(12 24±3 58)μmol/L,各疾病组Hcy水平明显较对照组高,其差异有统计学意义 (P<0 01 ); ( 2 )Hcy与VitB12、叶酸呈负相关,相关系数分别为-0 701和-0 443,P<0 01; (3)MTHFR基因 677位C→T的突变使Hcy水平升高, CC型 ( 13 41±5 78 )μmol/L,CT型 ( 16 81±4 22 )μmol/L,TT型(20 88±6 60)μmol/L,P<0 01;TT基因型是高Hcy血症的易感基因 (OR=84 46,P<0 05);TT基因型还是SLE的易感基因(OR=7 56,P<0 05)。结论　(1)SLE、RA、AS、uSpA4种疾病患者普遍存在高Hcy血症。(2)导致高Hcy血症的原因可能有叶酸、VitB12的水平降低和MTHFR基因的突变。(3)TT型基因是Hcy异常升高的易感基因,也是SLE的易感基因。     

A common mutation in the methylenetetrahydrofolate reductase gene is a determinant of hyperhomocysteinemia in epileptic patients receiving anticonvulsants.

Hyperhomocysteinemia is a condition caused by both genetic and nongenetic factors. To determine whether a common methylenetetrahydrofolate reductase (MTHFR) variant is related to elevated homocysteine concentrations in epileptic patients receiving anticonvulsants, we investigated the plasma total homocysteine (tHcy) level, folate level, and MTHFR 677 C --> T mutation using a polymerase chain reaction (PCR) and restriction fragment length polymorphism analysis with HinfI digestion in 103 patients with epilepsy and 103 normal controls. The prevalence of hyperhomocysteinemia (> or = 11.4 micromol/L, 90th percentile of control group) was higher in patients than in controls (25% v 10.0%, P = .007). The homozygosity for the 677 C --> T mutation of MTHFR was associated with elevated tHcy and low folate levels. The magnitude of hyperhomocysteinemia in MTHFR TT homozygotes was more pronounced in epileptic patients than in controls (18.2 +/- 1.6 v 9.1 +/- 1.2 micromol/L, P = .04). In epileptic patients, hyperhomocysteinemia was more frequent in MTHFR TT genotypes versus CT or CC genotypes (58% v 17% and 16%, P < .001). Multiple logistic regression analysis showed that MTHFR TT genotype was an independent predictor of hyperhomocysteinemia in epileptic patients receiving anticonvulsants (phenytoin and carbamazepine but not valproic acid), suggesting that gene-drug interactions induce hyperhomocysteinemia. These findings indicate that epileptic patients receiving anticonvulsants may have a higher folate requirement to maintain a normal tHcy level, especially homozygotes for MTHFR 677 C --> T mutation.     

Plasma folate, vitamin B(12), and total homocysteine and homozygosity for the C677T mutation of the 5,10-methylene tetrahydrofolate reductase gene in patients with Alzheimer's dementia. A case-control study.

BACKGROUND: Elevated total plasma homocysteine (tHcy) levels are considered a risk factor for cerebrovascular disease and may also play an important role in the pathogenesis of Alzheimer's disease (AD). High values of plasma tHcy and low levels of vitamin B(12) and folate are frequently present in AD patients. Moreover, the homozygous mutation (C677T) of the methylene tetrahydrofolate reductase (MTHFR) gene, related to a thermolabile type of the encoded enzyme, causes hyperhomocysteinemia by reducing the 5-methyltetrahydrofolate availability. OBJECTIVE: The aim of the study was to investigate plasma levels of folate, vitamin B(12) and tHcy in patients with AD. These values were also related to the severity and the duration of the disease and to the possible role of the MTHFR genotype (C677T). METHOD: Plasma tHcy levels, homozygosity for the C677T mutation of the MTHFR gene, and folate and vitamin B(12) plasma levels were evaluated in 74 patients with AD (45 men, 29 women, mean age 68 years) and in 74 healthy matched controls (42 men, 32 women, mean age 68 years). RESULTS: AD patients had higher mean (+/- SD) plasma levels of tHcy (20.9 +/- 15 micromol/l compared to 11.8 +/- 5 micromol/l, p < 0.001) and lower mean plasma folate (5.7 +/- 2.1 ng/ml compared to 8.5 +/- 3.2 ng/ml, p < 0.001) and vitamin B(12) (491 +/- 144 pmol/l compared to 780 +/- 211 pmol/l, p < 0.001) concentrations. Homozygosity for the C677T mutation of the MTHFR gene had a similar prevalence among controls (18%) and AD patients (20%). Homozygous AD patients (n = 15) had higher plasma tHcy values than nonhomozygotes, in spite of similar mean plasma folate and vitamin B(12) levels. This difference in plasma tHcy levels was not observed in controls. Patients with levels of plasma tHcy above and of plasma folate below the normal limits were more frequent in the homozygous AD group. The duration of the disease correlated with plasma levels of tHcy (r = +0.832, p < 0.001), plasma folate (r = -0.580, p < 0.05), and vitamin B(12) (r = -0.460, p < 0.05). However, when all the data were corrected for age, serum creatinine levels, and duration of the disease, mean plasma tHcy, folate, and vitamin B(12) levels were not statistically different between controls and AD patients. CONCLUSIONS: Our data suggest that rather than a risk factor for AD, hyperhomocysteinemia is related to its progression and increasing severity. This might be particularly relevant in homozygotes for the C677T mutation of the MTHFR gene and supports the possible need for continuous supplements in this setting.     

血浆叶酸、同型半胱氨酸水平及亚甲基四氢叶酸还原酶基因突变与静脉血栓栓塞症

目的 探讨血浆叶酸、同型半胱氨酸(Hcy)水平及亚甲基四氢叶酸还原酶(MTHFR)基因突变与静脉血栓栓塞症(VTE)的关系及MTHFR基因突变对血浆叶酸、Hcy水平的影响。方法 采用病例对照研究,对58例既往确诊为VTE(VTE组)的患者及与其性别、年龄相匹配的58例健康对照者(健康对照组)行流行病学调查,高效液相色谱分析法测血浆中Hcy、蛋氨酸和半胱氨酸水平,放射免疫法测血浆中叶酸水平,PCR-限制性片段长度多态性(RFLP)法测MTHFR C677T基因型。结果吸烟、高血压、糖尿病等危险因素均与VTE无关。血浆Hcy和叶酸浓度在2组间有明显差异(P<0.05)。多变量logistic回归分析显示,Hcy和叶酸浓度是影响VTE的独立因素(OR=1.5,95％CI为1.216～2.213;OR=0.396,95％CI为0.149-0.709)。MTHFR C667T基因突变在2组间差异无显著性(P>0.05)。血浆叶酸浓度与血浆Hcy浓度有明显关联(偏相关系数为-2.061,P<0.05)。MTHFR C667T。基因突变虽然与血浆Hcy浓度无关,但与血浆叶酸浓度相关(偏相关系数为0.5856,P<0.01)。结论 高同型半胱氨酸血症和叶酸缺乏是VTE独立的危险因素,叶酸缺乏是造成高同型半胱氨酸血症的原因之一,MTHFlR C667T基因突变可能是造成叶酸缺乏的遗传因素之一。     

Homocysteine and folate status in methotrexate-treated patients with rheumatoid arthritis

OBJECTIVE: To study (i) the influence of methotrexate (MTX) therapy on homocysteine and folate metabolism in patients with rheumatoid arthritis (RA), (ii) the influence of the C677T mutation in the methylenetetrahydrofolate reductase gene (MTHFR) on the change in plasma homocysteine levels during MTX treatment, and (iii) the interference of folate and homocysteine metabolism with the efficacy and toxicity of treatment with MTX. METHODS: The 113 patients enrolled in this study were participating in a 48-week, multicentre, double-blind, placebo-controlled study comparing the efficacy and toxicity of MTX treatment with and without folic or folinic acid supplementation. The MTX dose was 7.5 mg/week initially and increased to a maximum of 25 mg/week if necessary. Concentrations of total folate, 5-methyl tetrahydrofolate (in serum and in erythrocytes) and of homocysteine, cysteine and cysteine-glycine and the MTHFR genotype were determined before the start of the study, after 6 weeks, and after 48 weeks or on withdrawal from the study. Blood was drawn from fasting patients at a standardized time in the morning, 16 h after intake of MTX. The laboratory results were related to parameters of efficacy and toxicity of MTX treatment. RESULTS: Baseline values were distributed equally in the three treatment groups. The mean plasma homocysteine level (normal range 6-15 micromol/l) before the start of MTX was relatively high in all groups: 15.4 micromol/l [95% confidence interval (CI) 13.5 to 17.2] in the MTX plus placebo group (n=39), 14.3 micromol/l (95% CI 12.2 to 16.4) in the MTX plus folic acid group (n=35) and 15.9 micromol/l (95% CI 13.7 to 18.1) in the MTX plus folinic acid group (n=39). After 48 weeks of MTX therapy, the mean homocysteine level showed an increase in the placebo group (+3.6 micromol/l, 95% CI 1.7 to 5.6). In contrast, a decrease was observed in the groups supplemented with folic or folinic acid (folic acid, -2.7 micromol/l, 95% CI -1.4 to -4.0; folinic acid, -1.6 micromol/l, 95% CI -0.1 to -3.0). The differences in the change in plasma homocysteine level between the placebo group and each of the two folate-supplemented groups were statistically significant (P<0.0001), contrary to the difference between the folic and folinic acid groups (P=0.26). Linear regression analysis showed that the change in plasma homocysteine level was statistically significantly associated with folic or folinic acid supplementation (P=0.0001) but not with the presence or absence of the C677T mutation in the MTHFR gene. Homozygous mutants had a higher plasma homocysteine concentration at baseline. No relationship was found between the change in disease activity and the change in homocysteine concentration or the mean homocysteine concentration after 48 weeks of MTX therapy. Toxicity-related discontinuation of MTX treatment was not associated with the change in homocysteine concentration. CONCLUSIONS: Low-dose MTX treatment in RA patients leads to an increased plasma homocysteine level. Concomitant folate supplementation with either folic or folinic acid decreases the plasma homocysteine level and consequently protects against potential cardiovascular risks. No relationship was found between the change in homocysteine concentration and the presence or absence of the C677T mutation in the MTHFR gene. Homocysteine metabolism was not associated with efficacy or toxicity of MTX treatment.     

Hyperhomocysteinemia and hypercoagulability in primary biliary cirrhosis

AIM: To assess the hypercoagulability in PBC and its relationship with homocysteine (HCY) and various components of the haemostatic system. METHODS: We investigated 51 PBC patients (43F/8M; mean age: 63±13.9 yr) and 102 healthy subjects (86 women/16 men; 63±13 yr), and evaluated the haemostatic process in whole blood by the Sonoclot analysis and the platelet function by PFA-100 device. We then measured HCY (fasting and after methionine loading), tissue factor (TF), thrombin-antithrombin complexes (TAT), D-dimer (D-D), thrombomodulin (TM), folic acid, vitamin B6 and B12 plasma levels. C677T 5,10-methylenetetrahydrofolate reductase (MTHFR) polymorphism was analyzed. RESULTS: Sonoclot RATE values of patients were significantly (P< 0.001) higher than those of controls. Sonoclot time to peak values and PFA-100 closure times were comparable in patients and controls. TAT, TF and HCY levels, both in the fasting and post-methionine loading, were significantly (P< 0.001) higher in patients than in controls. Vitamin deficiencies were detected in 45/51 patients (88.2%). The prevalence of the homozygous TT677 MTHFR genotype was significantly higher in patients (31.4%) than in controls (17.5%) (P<0.05). Sonoclot RATE values correlated significantly with HCY levels and TF. CONCLUSION: In PBC, hyper-HCY is related to hypovitaminosis and genetic predisposing factors. Increased TF and HCY levels and signs of endothelial activation are associated with hypercoagulability and may have an important role in blood clotting activation.