乳腺癌亚甲基四氢叶酸还原酶基因多态性的临床意义

目的：探讨乳腺癌亚甲基四氢叶酸还原酶（MTHFR）基因多态性的临床意义。方法：收集54例乳腺癌女性患者血液样本（研究组）和93例正常女性血液样本（对照组）,均进行DNA提取、PCR扩增、DNA限制性片段长度多态性分析。分析MTHFR C677T、A1298C基因型在乳腺癌女性和正常女性中的分布差异。结果：PCR-RFLP法检测显示,MTHFR基因野生型纯合子CC(198 bp)只有1条带,MTHFR杂合子CT(198 bp、175 bp)产生2条带,MTHFR变异型纯合子TT(175 bp)只有1条带。研究组MTHFR 677CC、677CT和677TT基因型频率分别为37.04%、51.58%和11.11%,677C、677T等位基因频率分别为62.96%、21.51%;对照组MTHFR 677CC、CT和TT基因型频率分别为34.41%、48.39%和17.20%,677C、677T等位基因频率分别为37.04%、41.40%。两组MTHFR C677T基因型频率和等位基因频率比较差异均无统计学意义（P均>0.05）。研究组MTHFR 1298AA、AC、CC基因型频率分别为...     

亚甲基四氢叶酸还原酶基因C677T多态性与男性不育的相关性及机制研究

目的探讨亚甲基四氢叶酸还原酶(MTHFR)基因C677T基因多态性与男性不育人群精液质量指标的相关性及可能机制。方法回顾性分析我院2016年1月至2017年3月就诊的59名男性不育症患者的临床资料,根据MTHFR基因型C677T分型分为CC、CT和TT基因型3组,比较各组精子质量参数,包括各组重度少、弱精子症、严重少弱精子症和正常精子者的比例,精子存活率、DNA完整性和顶体完整性,同时分析各组精液活性氧(ROS)水平。结果 CT基因型组正常精子者比例显著低于CC基因型组(P0.05);TT基因型组重度少、弱精子症、严重少弱精子症比例显著高于CC基因型组,严重少弱精子症比例亦显著高于CT型组,正常精子比例显著低于CC型和CT型组(P均0.05)。CT基因型组精子存活率显著低于CC基因型组,TT基因型组精子存活率显著低于CC、CT基因型组(P均0.05)。TT基因型组较CC、CT基因型组精子DNA完整性相关指标均有显著升高(P0.05);TT基因型组精子顶体完整性则显著低于CC、CT基因型组(P0.05)。CT基因型组ROS水平显著高于CC基因型组(P0.05),TT基因型组ROS水平显著高于CC、CT基因型组(P0.05)。结论 MTHFR基因C677T基因多态性与男性不育人群的精子质量指标相关,可能与ROS水平增高有关。     

急性肠系膜静脉血栓形成与MTHFR基因C677T突变的相关性研究

目的：探讨亚甲基四氢叶酸还原酶(MTHFR) 基因C677T 突变在急性肠系膜静脉血栓形成(AMVT)发病中的意义。 方法：采用高效液相色谱法测定63例AMVT患者和128名健康对照者血浆的同型半胱氨酸(Hcy)水平, 放射免疫法测定血浆叶酸浓度；应用聚合酶链反应—限制性片段长度多态性方法进行MTHFR C677T 基因多态性分析, 并进行基因型及等位基因频率的计数。 结果：AMVT组和对照组血浆Hcy水平分别为(23.5±8.8) μmol/L和(12.7±6.9) μmol/L, 差异有统计学意义(P＜0.01)。Hcy水平与叶酸呈负相关(AMVT组：r=-0.42, P＜0.01；对照组：r=-0.39, P＜0.01)。MTHFR C677T TT基因型在AMVT组的分布频率为33.3 %, 高于对照组的17.2 %, 差异有统计学意义(χ2=6.31, P＜0.05)。结论：血浆Hcy水平升高是AMVT形成的危险因素之一。MTHFR C677T多态性中TT基因型可能是AMVT形成的一个重要遗传风险因子。     

MTHFR基因C677T多态性与蒙古族中老年男性骨质疏松的相关性

目的 探讨本地区蒙古族中老年男性亚甲基四氢叶酸还原酶（methylenetetrahydrofolate reductase ,MTHFR ）基因的多态性位点C677T基因多态性与内蒙古地区蒙古族中老年男性骨质疏松症(osteoporosis,OP)遗传易感性的关系。方法 收集门诊及住院蒙古族骨质疏松（包括骨质疏松性骨折）男性患者135例。对照组为按年龄配比的门诊体检内蒙古籍蒙古族中老年男性180例。入选者全部行腰椎（L2-L4）及股骨近端股骨颈骨密度扫查,并排除骨代谢疾病的影响,并进行MTHFR基因多态性检测。结果 骨质疏松组MTHFR基因受体C677T基因型CC、CT、TT频率分别为CC 25.2％、CT 40.0％和TT 34.8％;对照组基因型CC、CT、TT频率分别为31.2%,54.5%和14.3%,两组差别有统计学意义（P<0.05）。骨松组中的T等位基因频率为54.8%,显著高于对照组(41.6%,P<0.05),提示T是骨质疏松发生的危险因素(OR=1.70,95% CI=1.24～2.34,P=0.001)。与CC基因型相比,TT基因型携带者的骨松发生风险增加至2.97倍(95％ CI=2.57～5.65,P=0.001)。 结论 MTHFR基因型分布频率均符合 Hardy-Weinberg定律,T等位基因可以增加蒙古族中老年人骨折发生风险,MTHFR C677T基因变异与内蒙古地区蒙古族中老年男性骨质疏松易感性明显相关。     

MTHFR基因多态性与贵阳地区原发性不育症的关系研究

目的 研究亚甲基四氢叶酸还原酶(MTHFR)基因677和1298位点多态性与贵阳地区原发性男性不育症的关系。方法 选取2018年1月至2021年12月期间就诊于贵阳市妇幼保健院的254例原发性男性不育患者为病例组，以配偶自然受孕且生育过正常新生儿的238例健康男性为对照组。采用Taqman探针法检测两组MTHFR基因677和1298位点的基因型，并统计分析其基因型分布特点、等位基因分布频率以及MTHFR基因型与男性不育症的相关性。结果 基因检测结果显示，MTHFR 677位点包括CC、CT、TT三个基因型；1298位点包括AA、AC、CC三个基因型。病例组和对照组MTHFR基因677位点TT基因型频率分别为14.17%、14.71%,T等位基因频率分别为37.60%、36.13%;病例组和对照组1298位点CC基因型频率分别为5.51%、3.78%,C等位基因频率分别为23.43%、22.27%;两组间各位点基因型频率和等位基因频率比较均无统计学差异(P>0.05)。结论 MTHFR基因677和1298位点多态性与贵阳地区原发性男性不育症无明显关系。     

亚甲基四氢叶酸还原酶基因C677T和A1298C位点多态性与胃癌易感性的相关性分析

目的探讨亚甲基四氢叶酸还原酶(MTHFR)基因C677T和A1298C位点多态性与胃癌易感性的相关性。方法回顾性收集2008年1月至2014年1月期间在笔者所在医院住院的、行MTHFR基因C677T和A1298C位点检测的160例胃癌患者作为胃癌组,收集同期160名自愿接受上述基因检测的健康体检人员作为对照组,比较2组2种位点基因型的分布情况。结果胃癌组患者MTHFR基因C677T位点的基因型为:CC 72例,CT 64例,TT 24例;对照组为:CC 78例,CT 69例,TT 13例。胃癌组患者MTHFR基因A1298C位点的基因型为:AA 58例,AC 84例,CC 18例;对照组为:AA 62例,AC 77例,CC 21例。2组C677T位点及A1298C位点的基因型分布比较差异均无统计学意义(P>0.05)。结论 MTHFR基因C677T位点和A1298C位点多态性与胃癌的易感性无明显相关性。     

MTHFR基因多态性与蒙古族绝经后妇女骨质疏松的相关性研究

目的探讨本地区蒙古族绝经后妇女亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)基因的多态性位点C677T、A1298C基因多态性与内蒙古地区蒙古族绝经后女性骨质疏松症(osteoporosis,OP)遗传易感性的关系。方法收集150例门诊及住院(确诊为骨质疏松)蒙古族绝经后妇女为观察组,对照组来自门诊按年龄配比的骨含量正常的蒙古族绝经后妇女145例,均以双能X线骨密度仪测定腰椎和髋部骨密度,以T值≤-2.5诊断为骨质疏松,-2.5≤T≤-1.0为骨含量减少,T值-1.0为骨含量正常,并进行MTHFR C677T及A1298C基因多态性检测。结果骨质疏松组MTHFR基因受体C677T基因型CC、CT、TT频率分别为29.3%、44.0%和27.7%,对照组基因型CC、CT、TT频率分别为42.8%、44.8%和12.4%,两组差异有统计学意义(P=0.017)。骨质疏松症组中的T等位基因频率为48.7%,显著高于对照组(34.8%,P=0.005),提示T等位基因是骨质疏松发生的危险因素(OR=1.77,95%CI=1.18~2.64,P=0.001)。与CC基因型相比,TT基因型携带者的骨质疏松发生风险增加至3.15倍(95%CI=1.45~6.86,P=0.004),该作用在年龄≥60岁及体重指数偏高的女性中表现更明显。而MTHFR A1298C的多态性位点对绝经后骨质疏松的发生没有显著影响(P=0.513)。结论 MTHFR C677T基因变异与蒙古族绝经后妇女骨质疏松易感性明显相关,MTHFR A1298C的多态性位点与蒙古族绝经后妇女骨质疏松的发生没有明显相关性。     

MTHFR、MS基因多态及NF2基因甲基化与乳腺癌发病关系的研究

目的：本研究探讨MTHFR、MS基因多态性与抑癌基因NF2甲基化及乳腺癌发病的关系。方法：选取原发性乳腺癌患者47例,健康人52例及乳腺良性病变患者15例,采用RT-PCR、DNA甲基化特异性PCR（methylation-sPecific PCR,MSP）聚合酶链反应-限制性片段长度多态性（PCR-RFLP）技术检测NF2的基因表达、甲基化水平及MTHFR、MS基因多态性。结果：NF2基因的表达量在乳腺癌组织（0.16±0.11）及癌旁组织（0.27±0.14）明显低于乳腺良性病变组织（0.64±0.17,P〈0.05）。NF2基因甲基化发生率在乳腺癌组织和癌旁组织中分别为57.4%（27/47）和23.4%（11/47）,两组差异有统计学意义（P〈0.05）。MTHFR677等位基因T型较C等位基因T型在病例组和对照组分布有显著差异（P〈0.05）。携带MTHFR677TT基因型与携带MTHFRCC基因型比较,前者使乳腺癌患病风险增加5.44倍（95%CI,1.91~15.48）。MS2756等位基因G型较等位基因A型在病例组和对照组分布有显著差异（P〈0.05）。携带MS 2756AG基因型与携带MS 2756AA基因型比较,前者使乳腺癌患病风险增加2.73倍（95%CI,1.42~5.24）。MTHFR677多态性与NF2基因甲基化有相关性（χ2=7.29,P〈0.05）。MS2756多态性与NF2基因甲基化无显著关联。结论：NF2甲基化与乳腺癌发生密切相关,MTHFR677、MS2756多态性可以增加乳腺癌的患病风险,MTHFR677多态性可能通过影响部分肿瘤相关基因发生甲基化而调控其表达。     

GNB3 C825T等位基因多态性与原发性IgA肾病相关性研究

目的：研究G蛋白β3亚基（GNB3）C825T等位基因多态性与原发性IgA肾病（IgAN）的发生与病情进展。方法：病例组为216例原发性IgAN患者,对照组为200例健康志愿者。采用聚合酶链式反应-限制性片段长度多态性（PCR-RFLP）技术检测各组GNB3 825位点基因型。病例组分为高血压组与非高血压组;同时按基因型的不同将病例组分为TT组、CT组与CC组。结果：（1）病例组与对照组TT、CT、CC基因型频率分别为21.76%、54.63%、23.61%与18.00%、47.00%、35.00%,两组TT、TC、TT＋TC基因型与CC基因型分布频率存在统计学差异（P〈0.05）;病例组T等位基因分布频率高于对照组（49.07%vs 41.50%,P〈0.05）。（2）216例IgAN中,高血压组与非高血压组TT、CT、CC基因型频率分别为32.88%、49.31%、17.81%与16.09%、57.34%、26.57%（P〈0.05）。高血压组T等位基因频率较非高血压组明显增加（57.53%vs 44.76%,P〈0.05）。（3）病例组不同基因型携带者病理分级轻重无统计学差异（P〉0.05）。（4）病例组中不同基因型携带者在性别、年龄、体重指数、尿蛋白排泄量（〉1 g/d）、血肌酐水平、血胆固醇水平及三酰甘油水平无统计学差异（P〉0.05）,而高尿酸血症的发生存在统计学差异（P〈0.05）,TT组高尿酸血症患者较CT组及CC组高。结论：（1）病例组TT基因型和T等位基因频率较对照组明显增加,结果显示GNB3 825T等位基因可能与IgA肾病的发病有关,提示该基因可能与IgA肾病的遗传易感性相关。（2）GNB3 825T等位基因能影响IgA肾病患者高血压、高尿酸血症的发生。GNB3C825T等位基因多态性与IgA肾病发病及病情进展的相关机制有待进一步研究。     

186例少弱精子症患者MTHFR C677T基因多态性观察

目的观察186例少弱精子症男性不育患者的亚甲基四氢叶酸还原酶(MTHFR)C677T基因多态性的分布及频率。方法以186例少弱精子症的男性不育患者为不育组,同期就诊的有正常生育史和精液参数正常的男性131例为对照组,比较两组男性MTHFR C677T基因多态性的分布及频率差异。结果不育组中MTHFR基因CC基因型分布频率显著低于对照组(36.6%vs.55.0%,P<0.05),TT型分布频率则显著高于对照组(20.4%vs.13.7%,P<0.05),T等位基因的分布频率亦显著高于对照组(41.9%vs.29.4%,P<0.05)。结论 MTHFR基因C677T多态性可能与男性少弱精子症的发生相关,可能是造成男性不育的一个遗传学因素。但因本研究纳入的观察对象数量有限,结论存在一定的局限性,后续尚需更深入的研究探讨。     

MTHFR基因多态性与2型糖尿病肾病相关性的研究

目的 研究亚甲基四氢叶酸还原酶（MTHFR）基因多态性与2型糖尿病肾病（DN）易感性的关系.方法 选择111例山西地区汉族人2型糖尿病患者,其中糖尿病肾病（DN＋）组56例,糖尿病非肾病（DN-）组55例,运用聚合酶链式反应-限制性片段长度多态性（PCR-RFLP）技术并结合琼脂糖凝胶电泳的方法检测111例患者的MTHFR基因多态性,测定各组间基因型频率和等位基因频率.结果 纯合基因型TT、T等位基因在DN＋组（21.43％,46.43％）的频率均明显高于DN-组（7.27％,29.09％）,差异均具有统计学意义（P＜0.05）.无论是在DN＋组还是DN-组中,TT基因型患者血同型半胱氨酸（Hcy）平均水平均大于CC基因型和CT基因型患者,DN＋组血浆Hcy水平明显高于DN-组,差异均具有统计学意义（P＜0.05）.在叶酸浓度≤6.92nmol/L时,DN＋组（24.24％,48.49％） TT型发生率及T等位基因频率明显高于DN-组（3.70％,25.93％）（P＜0.05）,当叶酸浓度＞6,92nmol/L时,DN＋组TT型发生率及T等位基因频率与DN-组无差异（P＞0.05）.结论 MTHFR基因C677T多态性与糖尿病肾病（DN）发生具有相关性,突变的T等位基因是DN易感基因,但其影响效果受叶酸浓度的影响.     

Polymorphism in methylenetetrahydrofolate reductase gene: its impact on plasma homocysteine levels and carotid atherosclerosis in ESRD patients receiving hemodialysis

The methylenetetrahydrofolate reductase (MTHFR) gene polymorphism has been shown to be associated with cardiovascular disease in healthy subjects as well as in patients with end-stage renal disease (ESRD). In this study, we examined the allelic frequency and genotype distribution of the MTHFR gene in 151 Chinese ESRD patients receiving hemodialysis and 135 healthy controls. In addition, we investigated the relationship between the MTHFR gene polymorphism and the plasma homocysteine (Hcy) level as well as the intima-media thickness of common carotid artery (CC-IMT) in these patients. The allelic frequency of the MTHFR gene with the C677T mutation in ESRD patients was 24.5% and that in healthy controls was 23%. Mean plasma Hcy level of the ESRD patients (23.1 +/- 7.4 micromol/l) was significantly higher than that of the controls (10.1 +/- 5.0 micromol/l), but did not correlate with vitamin B(6) and vitamin B(12) status. Moreover, the extent of hyperhomocysteinemia was genetically affected by the C677T mutation of the MTHFR gene. The plasma Hcy levels for the patients with the CC, CT and TT genotypes of the MTHFR gene were 22.3 +/- 6.8, 22.8 +/- 7.3, and 28.3 +/- 2.8 micromol/l, respectively. In addition, we found that the patients bearing the TT genotype had the highest CC-IMT (0.93 +/- 0.07 mm), whereas the lowest values (0.79 +/- 0.13 mm) were observed in those who had the CC genotype. One-way ANOVA showed that the CC-IMT in the patients with the TT genotype was significantly greater than that of the patients with the CC genotype (p < 0.05). Moreover, the mean CC-IMT of the patients carrying either TT or CT genotype of the MTHFR gene was significantly higher than that of the patients bearing the CC genotype (0.86 +/- 0.14 vs. 0.79 +/- 0.13 mm, p = 0.002). Multiple regression analysis, in which the change in CC-IMT was used as the dependent variables, identified age, smoking, the MTHFR genotype (CC = 0, CT = 1, TT = 2) and diabetes mellitus as the independent variables significantly associated with the increase of CC-IMT (p < 0.001). These risk factors jointly explained 43.9% of the CC-IMT variation and age explained most of the variation (R(2) = 0.34). We conclude that both the TT genotype and the T allele of the MTHFR gene are associated with the increase of CC-IMT in hemodialysis patients. The C677T mutation of the MTHFR gene may be an independent risk factor that predicts the development of carotid atherosclerosis in ESRD patients.     

红细胞叶酸水平及叶酸代谢相关基因多态性与不良妊娠结局的相关性研究

目的检测不良妊娠结局患者叶酸水平及叶酸代谢相关基因亚甲基四氢叶酸还原酶(MTHFR)677CT、1298AC、还原叶酸载体(RFC-1)80AG的基因多态性分布,探讨其与不良妊娠结局的相关性。方法选取北京协和医院不良妊娠结局患者63例,正常对照人群48例,检测血清叶酸、红细胞叶酸和维生素B_(12);运用聚合酶链反应-限制性内切酶酶切片断长度多态性(PCR-RFLP)的方法检测相关基因MTHFR 677CT、1298AC、RFC-1 80AG的基因多态性;比较病例组和对照组叶酸水平和基因型分布的差异,以及不同基因型叶酸水平的差异。结果病例组虽然血清叶酸水平高于对照组,但红细胞叶酸水平显著低于对照组,分别为(234±1 20)μg/L和(284±88)μg/L(P0.05)。MTHFR 677CT与677CC在对照组和病例组之间的分布具有显著性差异(P0.05)。RFC-1 80GG与80AA在对照组和病例组之间的分布有显著性差异(P0.05)。RFC-1 80GG组对叶酸的转运(红细胞/血清叶酸比值)下降,与80AA组相比具有显著差异(P0.05)。结论红细胞叶酸水平降低与不良妊娠结局相关,MTHFR 677CT和RFC-1 80AG突变可能是发生不良妊娠结局的高危因素。     

Higher incidence of C677T polymorphism of the MTHFR gene in North Indian patients with vascular disease

Homocysteine is a sulfur-containing amino acid, which is derived from dietary methionine. Hyperhomocysteinemia has been implicated in vascular disease for over a decade now, and can be treated with B vitamins. Among its causes is polymorphism of the MTHFR gene, the most common being the cytidine to thymidine at position 677 (MTHFR C677T), which gives rise to three genotypes - normal homozygous CC, heterozygous CT and homozygous variant TT. An attempt was made to ascertain the prevalence of this MTHFR C677T in our population so that preventive measures may accordingly be instituted. Blood samples from 70 patients with vascular disease and 70 healthy controls were analyzed for plasma homocysteine levels (chemiluminescent immunoassay) and for the presence of MTHFR C677T (polymerase chain reaction analysis). Homocysteine was higher in the homozygous subjects (TT genotype) than in the heterozygous (CT genotype). In patients, the frequency of the C allele was significantly lower, and that of the T allele was significantly higher than the corresponding frequencies in controls. In conclusion, the North Indian urban population has higher homocysteine levels associated with the TT genotype. Hence, instituting measures towards reduction of homocysteine levels in the population would probably reduce the incidence and morbidity of vascular disease in our population.     

Methylenetetrahydrofolate reductase C677T polymorphism and the risk of male infertility: a meta-analysis

Several molecular epidemiological studies have been conducted to examine the association between MTHFR C677T polymorphism and male infertility susceptibility, but the results remain inconsistent. To derive a more precise estimation of the relationship, a meta-analysis was performed. A total of 10 case-control studies, including 2275 cases and 1958 controls, were selected. Crude odds ratios (ORs) with 95% confidence intervals were used to assess the strength of association in the additive model, dominant model and recessive model. In the overall analysis, no significant association between the polymorphism and risk of male infertility was observed. Stratified analysis showed that significantly strong association between MTHFR C677T polymorphism and male infertility were present only in Asians (OR = 1.79 for TT vs. CC genotype; OR = 1.42 for CT/TT vs. CC genotype; OR = 1.50 for TT vs. CC/CT genotype; OR = 1.36 for T vs. C allele), but not in Caucasians. Additionally, MTHFR 677T was associated with a significant increase in the risk of azoospermia in all genetic models. No significantly increased risks of oligoasthenoteratozoospermia were found in any of the genetic models. In conclusion, this meta-analysis supports that MTHFR C677T polymorphism is capable of causing male infertility susceptibility in Asians, but not in Caucasians.     

Effect of MTHFR 677C>T on plasma total homocysteine levels in renal graft recipients

BACKGROUND: Hyperhomocysteinemia is an established, independent risk factor for vascular disease morbidity and mortality. The 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphism C677T has been shown to result in increased total homocysteine concentrations on the basis of low folate levels caused by a decreased enzyme activity. The effect of this polymorphism on total homocysteine and folate plasma levels in renal transplant patients is unknown. METHODS: We screened 636 kidney graft recipients for the presence of the MTHFR C677T gene polymorphism. The major determinants of total homocysteine and folate plasma concentrations of 63 patients, who were identified to be homozygous for this gene polymorphism compared with heterozygotes (N = 63), and patients with wild-type alleles (N = 63), who were matched for sex, age, glomerular filtration rate (GFR), and body mass index, were identified by analysis of covariance. The variables included sex, age, GFR, body mass index, time since transplantation, folate and vitamin B12 levels, the use of azathioprine, and the MTHFR genotype. To investigate the impact of the kidney donor MTHFR genotype on total homocysteine and folate plasma concentrations, a similar model was applied in 111 kidney graft recipients with stable graft function, in whom the kidney donor C677T MTHFR gene polymorphism was determined. RESULTS: The allele frequency of the C677T polymorphism in the MTHFR gene was 0.313 in the whole study population [wild-type (CC), 301; heterozygous (CT), 272; and homozygous mutant (TT), 63 patients, respectively] and showed no difference in the patient subgroups with various renal diseases. The MTHFR C677T gene polymorphism significantly influenced total homocysteine and folate plasma concentrations in renal transplant recipients (P = 0.0009 and P = 0.0002, respectively). Furthermore, a significant influence of the GFR (P = 0.0001), folate levels (P = 0.0001), age (P = 0.0001), body mass index (P = 0.0001), gender (P = 0.0005), and vitamin B12 levels (P = 0.004) on total homocysteine concentrations was observed. The donor MTHFR gene polymorphism had no influence on total homocysteine and folate levels. Geometric mean total homocysteine levels in patients homozygous for the mutant MTHFR allele were 18.6 micromol/liter compared with 14.6 micromol/liter and 14.9 micromol/liter in patients heterozygous for the MTHFR gene polymorphism and those with wild-type alleles (P < 0.05 for TT vs. CT and CC). Geometric mean folate levels were lower in CT and TT patients (11.2 and 10.2 nmol/liter) compared with CC patients (13.6 nmol/liter, P < 0.05 vs. CT and TT). CONCLUSIONS: This study demonstrates that homozygosity for the C677T polymorphism in the MTHFR gene significantly increases total homocysteine concentrations and lowers folate levels in kidney graft recipients, even in patients with excellent renal function (GFR more than median). These findings have important implications for risk evaluation and vitamin intervention therapy in these patients who carry an increased risk for the development of cardiovascular disease.     

Effect of MTHFR 1298A-->C and MTHFR 677C-->T genotypes on total homocysteine, folate, and vitamin B(12) plasma concentrations in kdiney graft recipients

The effect of 5,10-methylenetetrahydrofolate reductase (MTHFR) 677C-->T and 1298A-->C on total homocysteine (tHcy), folate and vitamin B(12) levels was investigated in 733 kidney graft recipients. The six major genotype combinations were used as grouping variables, and age, gender, BMI, serum creatinine, and creatinine clearance and ln-folate, ln-vitamin B(12), or logarithmus naturalis tHcy (ln-tHcy) were used as covariates in three ANCOVA and multiple stepwise linear regression models. Hyperhomocysteinemia was present in 49.7% of the patients. The allele frequency of MTHFR 677T and 1298C was 0.319 and 0.326. MTHFR genotype and all other variables were significant predictors of ln-tHcy (higher tHcy plasma levels for MTHFR 677TT/1298AA versus all other five genotype groups: P < 0. 05). BMI, creatinine clearance, ln-tHcy, and MTHFR genotype influenced ln-folate (lower folate levels for MTHFR 677TT/1298AA versus all other genotype groups: P < 0.05). Creatinine clearance and ln-tHcy were the only predictors of ln-vitamin B(12) levels. In a prespecified subgroup analysis (n = 496), the MTHFR genotype also influenced tHcy levels and compound heterozygous patients had significantly lower folate levels as compared with MTHFR 677CC/1298AA and 677CC/1298CC. This study shows that the MTHFR 677TT/1298AA and 677CT/1298AC genotypes are significant predictors of tHcy and folate plasma levels.     

Methylenetetrahydrofolate reductase (MTHFR) C677T polymorphism is associated with osteoporotic vertebral fractures, but is a weak predictor of BMD

Osteoporosis is a common disease with a strong genetic component. Linkage studies have suggested linkage between BMD and loci on chromosome 1. The MTHFR gene is located on chromosome 1. MTHFR catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methylenetetrahydrofolate, which is used for homocysteine methylation to methionine. The rare genotype (TT) of the C677T polymorphism has previously been demonstrated to be associated with increased plasma homocysteine levels in individuals with inadequate plasma folate levels. Recently, the TT genotype has been found to be associated with reduced bone mass. We therefore examined if the C677T polymorphism in the MTHFR gene is associated with changes in bone mass and risk of osteoporotic fractures in 388 osteoporotic patients and 336 normal individuals. The distributions of the genotypes CC, CT and TT in women with osteoporotic vertebral fractures and normal controls were 43.5%, 42.2% and 14.3% and 52.0%, 42.0% and 8.0%, respectively, ²=5.62, P=0.06. Since studies of the functionality of this polymorphism have revealed that only the TT genotype is associated with biochemical changes, we also compared the prevalence of the TT genotype versus the CT- and CC genotypes in patients and controls and found that the TT genotype is significantly more common in women with vertebral fractures (14.3%) compared with normal controls (8.0%), ²=4.31, P<0.05. Logistic regression analysis demonstrated that vertebral fractures were significantly associated with BMD (lumbar spine) and height but only marginally with the MTHFR genotype (P=0.06). Multiple linear regression analysis revealed that weight, age and the MTHFR polymorphism were predictors of lumbar spine BMD in women. However, age- and gender-corrected BMD of the lumbar spine and the hip was not significantly different between MTHFR genotypes. Furthermore, individuals with the TT genotype did not have BMD significantly lower than the combined group of individuals with the CT- or CC genotypes. In conclusion, we have demonstrated that the rare TT genotype of the C677T polymorphism in the MTHFR gene is associated with increased risk of osteoporotic fractures in women and a weak predictor of lumbar spine BMD.