血清同型半胱氨酸水平、亚甲基四氢叶酸还原酶基因多态性与糖尿病视网膜病变的相关性研究

目的探讨血清同型半胱氨酸（Hcy）水平、亚甲基四氢叶酸还原酶（MTHFR）基因的分布情况与糖尿病视网膜病变（DR）的关系。方法应用聚合酶链反应和限制性片断长度多态性（PCR-RELP）方法检测47例健康对照组和50例糖尿病视网膜病变患者MTHFR基因的677碱基多态性突变C—T情况，同时测定其血清Hcy水平和叶酸水平，进行对照分析。结果糖尿病视网膜病变患者MTHFR基因突变型C677T基因的频率明显高于对照组。差异有显著性（P〈0．05），且Hcy水平明显增高。在叶酸浓度≤6．92nmol／L时。DR组1Tr型发生频率及T等位基因频率明显高于对照组（P〈0．05）；但当叶酸浓度〉6．92nmol／L时。DR组TT型发生频率及T等位基因频率与对照组无差异（P〉0．05）。结论MTHFR基因C677T位碱基突变导致血浆Hcy水平升高是糖尿病视网膜病变发病的重要危险因素。但受叶酸浓度的影响。     

血浆同型半胱氨酸水平及MTHFR基因多态性与血管性痴呆的关系

目的探讨血浆同型半胱氨酸(Hcy)水平及MTHFR基因多态性与血管性痴呆(VD)的关系。方法采用高效液相色谱分析法检测法测定68例VD及34例非痴呆脑梗死患者的血浆总同型半胱氨酸水平,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)检测MTHFR基因多态性。结果VD脑梗死患者的平均血浆总同型半胱氨酸水平为18.54±9.21,VD患者的血浆总同型半胱氨酸水平显著高于非痴呆脑梗死组(P<0.01);MTHFR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,差异均无统计学意义(P>0.05)。结论高同型半胱氨酸血症可能是血管性痴呆(VD)独立危险因素之一。     

MTHFR基因多态性与老年冠心病及同型半胱氨酸的相关性研究

目的探讨N5,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）与老年冠心病的相关性。方法应用高效液相色谱法和多聚酶链反应限制性内切酶片段长度多态性技术检测并比较了120例老年冠心病患者（CHD组）和58例健康老年人（对照组）的血浆Hcy浓度及MTHFR基因型。结果两组MTHFR 677位点基因型分布和各等位基因频率比较均有统计学差异（P均〈0.05）;CHD组T等位基因频率及血浆Hcy浓度高于对照组（P均〈0.05）。结论 MTHFR基因突变可导致血浆Hcy浓度升高,高Hcy浓度及MTHFR基因T型均为老年CHD的高危因素。     

唐氏综合征患儿母亲MTHFR C677T基因多态性及血浆叶酸、同型半胱氨酸水平的研究

目的研究浙南地区汉族妇女叶酸及代谢产物同型半胱氨酸水平、亚甲基四氢叶酸还原酶(MTHFR)基因C677T位点多态性与唐氏综合征(Down’s Syndrome,DS)发生的关系。方法对84例已生育DS患儿的母亲(观察组)和120例生育过正常儿童的母亲(对照组)采用PCR扩增及DNA测序法检测亚甲基四氢叶酸还原酶基因MTHFR C677T单核苷酸多态性;免疫发光法检测叶酸(Folate)及循环酶法检测血浆同型半胱氨酸(Hcy)水平。结果 MTHFR 677 T基因及CT、TT基因型的频率两组无统计学意义(P>0.05)。对观察组与对照组的部分标本行血浆Folate与Hcy水平测定,观察组Folate水平显著高于对照组(t=-5.572,P<0.05);Hcy水平两组平均水平无统计学意义(t=0.152,P>0.05);Fo-late与Hcy水平呈负相关关系(r=-0.217,P<0.05)。观察组与对照组MTHFR 677CT、TT基因型与CC基因型Hcy水平比较均无统计学意义(P>0.05),观察组TT基因型Hcy水平比对照组有显著性升高(t=2.546,P<0.05)。结论本研究MTHFR C677T位点不是浙南地区汉族妇女DS的风险因素;DS母亲Folate水平高于对照组及MTHFR 677 TT基因型Hcy水平高于对照组,可能存在影响叶酸代谢的其他相关基因的多态性或营养的缺乏,有待进一步深入研究。     

临沂市汉族女性MTHFR和MZRR基因多态性分布及其与同型半胱氨酸水平的相关性

目的 分析山东省临沂市汉族女性亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)677C/T、1298A/C及甲硫氨酸合成酶还原酶(methionine synthase reductase,MTRR)66A/G基因多态性的分布特征,及其与同型半胱氨酸(homocysteine,Hcy)水平的相关性.方法 采用横断面调查研究方法,以临沂市825名汉族女性为研究对象,采集口腔黏膜上皮细胞,提取基因组DNA,采用Taqman-MGB技术进行MTHFR和MTRR基因多态性检测.统计分析基因多态性的分布特征,并与其他地区(山东省潍坊市、河南省郑州市、四川省德阳市及海南省)的数据进行比较.采用酶转换法检测281名研究对象的血浆Hcy浓度,根据MTHFR基因多态性将其分为MTHFR酶活性基本正常组和显著降低组,分析Hcy水平与MTHFR酶活性的相关性.结果 (1)临沂市汉族女性的MTHFR677CC、CT、TT的基因型频率分别为16.7%、48.3%和35.0%,TT纯合突变高于四川德阳和海南地区(P<0.01).MTHFR 1298AA、AC、CC的基因型频率分别为76.0%、21.6%和2.4%,CC纯合突变基因型频率低于四川德阳和海南地区(P<0.01).MTRR 66AA、AG、GG的基因型频率分别为54.7%、39.4%和5.9%,GG纯合突变基因型频率低于海南地区(P<0.01).(2)MTHFR酶活性显著降低组的Hcy水平高于酶活性基本正常组,差异有统计学意义(P<0.05).结论 (1)临沂市汉族女性有不同于其他地区的MTHFR和M7RR基因多态性分布特征.(2)MTHFR基因多态性导致的酶活性降低是Hcy水平升高的风险因素.     

叶酸代谢相关基因多态性及血浆同型半胱氨酸与唐氏综合征关系研究

目的研究叶酸代谢相关的亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTH-FR)基因多态性与唐氏综合征(Down syndrome,DS)发生的关系。方法选择100例生育过DS患儿的汉族母亲及100名相匹配的正常对照组母亲,PCR-限制性片段长度多态性方法检测MTHFR677C/T的基因型,化学发光法检测血浆中同型半胱氨酸(homocysteine,HCY)的水平。结果病例组MTHFR677T等位基因的频率较对照组增高,差异有统计学意义(P=0.002);杂合基因型CT的比值比为2.12(95%CI:1.14～3.94);而纯合基因型TT的比值比为3.43(95%CI:1.41～8.36)。平均血浆HCY浓度在病例组[(9.04±3.85)μmol/L]较对照组[(6.53±2.06)μmol/L]增高,差异有统计学意义(P<0.01)。MTHFR677位点一个和(或)两个等位基因C→T的变异,不论在病例组还是对照组均可引起HCY水平的显著增加(P<0.01)。同为MTHFR677CC基因型,病例组中的血浆HCY浓度仍较对照组增高(P<0.01),这种增加不依赖于MTHFR的基因型。结论血浆HCY和叶酸代谢相关基因的遗传多态性是汉族妇女生育DS患儿的危险因素。     

MTHFR基因多态性与血浆同型半胱氨酸在妊娠期高血压疾病的相关性研究

目的 探讨四氢叶酸还原酶（MTHFR）C677T基因多态性及血浆同型半胱氨酸（Hcy）在妊娠期高血压疾病（HDP）发病机制中的作用。方法 用过枉法提取基因型DNA，并行聚合酶链反应物-直接测序法检测和分析MTHFR基因中C677T的分型，用微粒酶免疫发光法测量血浆同型半胱氨酸水平。结果 ①HDP组与对照组C677／T677比较差异有统计学意义（P〈0．05），HDP组T677等位基因频率（0．488）显著高于对照组（0．325），两组比较差异有统计学意义（P〈0．01）。②轻度子痫前期组、重度子痫前期组的血浆Hcy水平均高于对照组，分别比较，差异均有统计学差异（P〈0．001）。结论 ①妊娠期高血压疾病患者的MTHFR C677T基因多态性可能是妊娠期高血压疾病发生的诱因之一，T667等位基因可能是妊娠高血压疾病的易感基因。②血浆Hcy水平升高可能是子痫前期发病的危险因素。     

妊娠高血压综合征与MTHFR A1298C基因及血浆同型半胱氨酸水平的关系

目的探讨妊娠高血压综合征与N5,N10鄄亚甲基四氢叶酸还原酶(MTHFRA1298C)基因及血浆同型半胱氨酸(Hcy)水平的关系。方法运用多聚酶链反应鄄限制性内切酶片段长度多态性技术(PCR鄄RFLP)检测54例妊高征患者,100例正常妊娠妇女(MTHFRA1298C基因多态性,采用荧光偏振免疫法(FPIA)测定血浆总Hcy水平。结果MTHFRA1298C三种基因型频率与对照组相比差异无显著性,与患者不同临床特征无明显关联。妊高征组总Hcy水平明显高于正常妊娠组(P<0.05)。结论MTHFRA1298C基因突变与妊高征发生无关;高同型半胱氨酸血症是妊高征发病的一个新的危险因素。     

甲基四氢叶酸还原酶基因多态性与糖尿病肾病关系的研究

目的：探讨甲基四氢叶酸还原酶（methylenetetrahydrofolate reductase,MTHFR)基因多态性与糖尿病肾病（diabetic nephropathy,DN)发生的关系。方法：利用聚合酶链反应－限制性片段长度多态性分析法（PCR－RFLP）检测了85名健康人和经尿微量白蛋白检测确诊的82例合并DN和79例无DN的2型糖尿病患者MTHFR基因第677位碱基多态性。结果：DN患者MTHFR基因变异型纯合子和等位基因频率均明显高于无肾病患者及健康者,P＜0．01。结论：MTHFR基因第677位碱基变异可能是中国汉族人DN发生的一个遗传危险因子。     

Serum homocysteine, vitamin B12, folic acid levels and methylenetetrahydrofolate reductase (MTHFR) gene polymorphism in vitiligo

The aim of this study was to determine serum vitamin B12, folic acid and homocysteine (Hcy) levels as well as MTHFR (C677, A1298C) gene polymorphisms in patients with vitiligo, and to compare the results with healthy controls. Forty patients with vitiligo and 40 age and sex matched healthy subjects were studied. Serum vitamin B12 and folate levels were determined by enzyme-linked immunosorbent assay. Plasma Hcy levels and MTHFR polymorphisms were determined by chemiluminescence and real time PCR methods, respectively. Mean serum vitamin B12 and Hcy levels were not significantly different while folic acid levels were significantly lower in the control group. There was no significant relationship between disease activity and vitamin B12, folic acid and homocystein levels. No significant difference in C677T gene polymorphism was detected. Heterozygote A1298C gene polymorphism in the patient group was statistically higher than the control group. There was no significant relationship between MTHFR gene polymorphisms and vitamin B12, folic acid and homocysteine levels. In conclusion, vitamin B12, folate and Hcy levels are not altered in vitiligo and MTHFR gene mutations (C677T and A1298C) do not seem to create susceptibility for vitiligo.     

生育过神经管缺陷儿的妇女MTHFR基因C677T多态性与血浆Hcy水平测定

目的探讨MTHFR基因C677T多态性及血浆Hcy水平与神经管缺陷的关系。方法采用PCR-RFLP方法对30例生育过NTD患儿的母亲（NTD组）和34例生育过正常儿的母亲（对照组）进行MTHFR基因C677T等位基因检测,同时用高效液相色谱结合荧光检测法对两组母亲血浆中Hcy水平进行测定。结果NTD母亲组中VV基因型的频率为（36.7%）,V等位基因频率为（65.0%）,正常对照母亲组中VV基因型的频率为（17.6%）,V等位基因频率为（44.1%）,两组比较有显著性差异（P〈0.05）。NTD母亲组Hcy水平为（11.24±3.2）μmol/L,正常对照母亲组Hcy水平为（8.96±3.3）μmol/L,两组比较也有显著性差异（P〈0.01）。结论MTHFR基因C677T多态是神经管缺陷发病的遗传危险因素,它通过血浆中同型半胱氨酸水平升高而引起神经管缺陷。     

血清同型半胱氨酸、叶酸、亚甲基四氢叶酸还原酶与HBV感染后疾病进展关系的研究

目的分析不同进展阶段乙型肝炎病毒（HBV）感染者血清中同型半胱氨酸（HCY）、叶酸和亚甲基四氢叶酸还原酶（MTHFR）的水平、相关性及其与肝病进展的关系。方法按照性别、年龄和基因型均匹配的原则挑选乙型肝炎自愈组（男性15例,女性15例;年龄37～66岁,平均年龄52．90岁）、肝硬化组（男性15例,女性15例：年龄36-73岁,平均年龄54.87岁）和肝癌组（男性15例,女性15例：年龄38～78岁．平均年龄56．37岁）研究对象各30例,采用酶联免疫吸附分析（ELISA）检测试剂盒检测血清HCY、MTHFR和叶酸的水平。结果血清叶酸和MTHFR水平在自愈组中显著高于肝硬化组和肝癌组（P〈0．01）。3个血清学指标的相关性分析显示,叶酸和MTHFR在各组均呈显著的正相关（P〈0．01）：在肝癌组中,HCY与叶酸和MTHFR也具有显著的正相关关系（P〈0．01）。3个指标在终末期肝脏疾病患者（肝癌组和肝硬化组）不同临床特征的组别间分层分析显示,随着肝功能下降,血清HCY水平增高,且差异具有统计学意义（P〈0．05）：HBsAg（-）和HBVDNA（〈500copies／mL）的终末期肝病患者血清MTHFR和叶酸水平分别高于HBsA（＋1）和HBVDNA（≥500copies／mL）者（P〈0．05）。结论男性、血清叶酸和MTHFR浓度降低是HBv感染后疾病恶性进展的风险因素。     

变性高效液相色谱检测5,10-亚甲基四氢叶酸还原酶基因677(C/T)多态

目的建立快速、准确的筛查5，10-亚甲基四氢叶酸还原酶基因（methylenetrahydrofolate reduclase gene，MTHFR）677（C／T）多态的方法。方法MTHFR扩增后，应用变性高效液相色谱进行检测，用测序和酶切验证。结果对334名南方汉族人的MTHFR的677（C／T）多态进行了检测，准确率达99％以上，灵敏度高，突变的检出率达100％。CC、CT、TT基因型的频率分别为56．9％、38．3％和4．8％，T、C等位基因的频率分别为23．95％和76．05％。结论变性高效液相色谱法能快速、准确地检测MTHFR的677（C／T）多态。MTHFR的677（C／T）多态存在地区和种族差异。     

The relationship between C677T methylenetetrahydrofolate reductase gene polymorphism and retinopathy in type 2 diabetes: a meta-analysis

The association between retinopathy in type 2 diabetes [diabetic retinopathy (DR)] and the C677T polymorphism in the methylenetetrahydrofolate reductase (MTHFR) gene has been investigated in several case-control studies. These studies rendered contradictory results, some indicating that the polymorphism is associated with the risk of developing DR whereas others concluded there is no association. To shed light on these inconclusive findings, a meta-analysis of all available studies relating the C677T polymorphism to the risk of developing DR was conducted. Four out of five identified studies included populations of East Asian descent, and only one involved samples from European descent (Caucasians). Overall, the meta-analysis suggested large heterogeneity between studies (p = 0.08, I² = 52%) and marginal association between C677T transition and the risk of developing DR: random effects odds ratio (OR) = 1.39 [95% CI (1.05, 1.83)]. The sensitivity analysis [exclusion of one East Asian study with the controls not in Hardy–Weinberg equilibrium (HWE)] showed no heterogeneity (p = 0.25, I² = 27%) and no significant association: fixed effects OR = 1.22 [95% CI (0.99, 1.51)] and random effects OR = 1.24 [95% CI (0.96, 1.60)]. The sub-group analysis for the East Asian population produced a significant association: fixed effects OR = 1.48 [95% CI (1.20, 1.83)] and random effects OR = 1.52 [95% CI (1.14, 2.03)]. However, sensitivity analysis in East Asians revealed that the association is marginal: fixed effects OR = 1.33 [95% CI (1.04, 1.70)] and random effects OR = 1.36 [95% CI (1.01, 1.83)]. There is a source of bias in the selected studies: the largest studies failed to show association while the smallest study claimed an association. The above findings reinforce the need for larger and more rigourous studies in this area.     

Urinary 6-sulfatoxymelatonin level in diabetic retinopathy patients with type 2 diabetes

Melatonin is a powerful antioxidant. Decreased melatonin excretion has been reported to be associated with several oxidative stress-related diseases. The urinary metabolite of melatonin, 6-sulfatoxymelatonin (aMT6s), has proved to be a very reliable index of melatonin production. The present study aims to evaluate the level of urinary aMT6s in patients with type 2 diabetes mellitus and diabetic retinopathy. Urine samples were collected from 10 patients with diabetes and no diabetic retinopathy (NDR), 19 patients with nonproliferative diabetic retinopathy (NPDR), 38 patients with proliferative diabetic retinopathy (PDR), and 16 subjects without diabetes mellitus, who served as controls. The level of aMT6s in specimens was assayed by a commercial aMT6s ELISA kit, creatinine levels were also measured for each sample to get urinary aMT6s/creatinine ratio. Creatinine-adjusted urinary aMT6s values were compared among four groups. The urinary aMT6s (mean ± SD) levels were 9.95 ± 2.42, 9.90 ± 2.28, 8.40 ± 1.84 and 5.58 ± 1.33 ng/mg creatinine in the controls and in patients with NDR, NPDR, or PDR, respectively. The urinary aMT6s level of the PDR group was significantly lower than that of the control, NDR and DR groups. No significant difference was found among the control, NDR and DR groups. After adjustment for various factors (age, smoking, cancer, and coronary heart disease) that may influence the aMT6s level, the odds-ratio of urinary aMT6s comparing PDR patients to controls was 0.246 (95% confidence interval = 0.108-0.558, P = 0.001). Therefore, the urinary aMT6s level is significantly decreased in diabetic patients with PDR but not in diabetic patients without PDR, which indicates that decreased urinary aMT6s level may be associated with the pathogenesis of PDR.     

MTHFR基因C677T多态与神经管缺陷及先兆子痫关系的研究

目的 探讨亚甲基四氢叶酸还原酶（ｍｅｔｈｙｌｅｎｅｔｅｔｒａｈｙｄｒｏｆｏｌａｔｅ ｒｅｄｕｃｔａｓｅ,ＭＴＨＦＲ）基因Ｃ６７７Ｔ多态与神经管缺陷（ｎｅｕｒａｌ ｔｕｂｅ ｄｅｆｅｃｔｓ,ＮＴＤ）及先兆子痫发生的关系。方法 采用ＰＣＲ／ＲＦＬＰ技术对２７位生过ＮＴＤ患儿的母亲和２４位生过正常孩子的母亲,以及５７例患过先兆子痫的妇女和１２０名正常对照妇女进行了ＭＴＨＦＲ等位基因检测。结果 （１）下沉     

Manganese superoxide dismutase gene polymorphism (V16A) is associated with diabetic retinopathy in Slovene (Caucasians) type 2 diabetes patients

Substantial data indicate that oxidative stress is involved in the development of diabetic retinopathy. Two candidate genes that affect the oxidative stress are manganese mitochondrial superoxide dismutase (Mn-SOD) and endothelial nitric oxide synthase (eNOS). The aim of the present study was to examine the role of the V16A polymorphism of the Mn-SOD gene and the 4a/b polymorphism of the eNOS gene in the development of diabetic retinopathy in Caucasians with type 2 diabetes. In this cross sectional case-control study 426 unrelated Slovene subjects (Caucasians) with type 2 diabetes mellitus were enrolled: 283 patients with diabetic retinopathy and the control group of 143 subjects with type 2 diabetes of duration of more than 10 years who had no clinical signs of diabetic retinopathy. A significantly higher frequency of the VV genotype of the V16A polymorphism of the Mn-SOD was found in patients with diabetic retinopathy compared to those without diabetic retinopathy (OR=2.1, 95% whereas the 4a/b polymorphism of the eNOS gene failed to yield an association with diabetic retinopathy. We may conclude that the VV genotype of the V16A polymorphism of the Mn-SOD gene was associated with diabetic retinopathy in Caucasians with type 2 diabetes, therefore it might be used as a genetic marker of diabetic retinopathy in Caucasians.