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。     

无精子症患者中MTHFR C677T、A1298C及MTRR A66G基因多态性分析

目的 探讨亚甲基四氢叶酸还原酶(MTHFR) C677T、A1298C及蛋氨酸合成酶还原酶(MTRR) A66G基因多态性在男性无精子症患者中的分布情况。方法 选取于2020年1月至2023年8月就诊于新疆佳音医院不孕不育门诊的97名无精子症患者,所有患者进行睾丸组织活检并基因测序MTHFR C677T、A1298C及MTRR A66G基因的多态性。按照手术中是否找到精子将患者分为有精子组(n=70)和无精子组(n=27),比较两组患者的基本资料以及MTHFR C677T、A1298C及MTRR A66G基因型多态性的频率及等位基因频率分布。结果 两组患者间年龄、体质量指数(BMI)以及是否伴随精索静脉曲张的差异均无统计学意义(P>0.05)。MTHFR C677T包括CC、CT、TT三个基因型及C、T两个等位基因,A1298C包括AA、AC、CC三个基因型及A、C等位基因;MTRR A66G包括AA、AG、GG三个基因型,A、G两个等位基因。有精子组和无精子组患者的MTHFR基因677位点TT基因型频率分别为18.6%、18.5%,T等位基因频率分别为42.1%、40.7%;M...     

少弱精子症与亚甲基四氢叶酸还原酶C677T基因多态性分布及频率的相关性分析

目的分析少弱精子症患者的亚甲基四氢叶酸还原酶(MTHFR)C677T基因多态性分布及频率。方法选取128例少弱精子症患者视为观察组,选取同期正常精液参数的正常男性108例视为对照组,对两组样本进行MTHFR C677T基因多态性的分布及频率做差异性分析。结果观察组中MTHFR基因CC型基因分布频率显著低于对照组(14.84%vs 29.63%P0.05),TT型基因显著高于对照组(37.50%vs 19.44%P0.05)。T等位基因分布频率不育组显著高于对照组(47.66%vs 44.91%P0.05)。结论 MTHFR C677T基因多态性可能与少弱精子症相关,CT基因型和TT基因型个体患少弱精子症的风险较高。     

MTHFR基因多态性在台州地区原发性男性不育症中的研究

目的探讨亚甲基四氢叶酸还原酶(MTHFR)基因C677T和A1298C位点多态性与原发性男性不育症的关系。方法选取2018年1～7月在台州市中心医院就诊的的原发性男性不育患者104例为研究对象,选取同期健康查体的已育男性108例为对照组。采用荧光定量PCR技术检测104例男性不育症患者和108例健康已育男性的MTHFR C677T和A1298C位点的多态性,统计学分析不同基因型男性与原发性不育的相关性。结果原发性男性不育组和健康对照组MTHFRC677T位点TT基因型频率分别为23.08%、12.96%,T等位基因频率分别为43.75%、33.33%,两组间基因型频率和基因频率均存在显著性差异(χ~2=6.975,χ~2=4.859,P0.05);原发性男性不育组和健康对照组的MTHFR A1298C位点CC基因型频率和C等位基因频率均无显著性差异(χ~2=0.108,χ~2=0.170,P0.05)。结论 MTHFR基因677位点C-T变异与原发性男性不育具有相关性,1298位点多态性与原发性男性不育无显著相关性。     

亚甲基四氢叶酸还原酶基因多态性与食管癌易感性关系的Meta分析

目的探讨亚甲基四氢叶酸还原酶(MTHFR)基因C677T和A1298C多态性与食管癌易感性间的关系。方法计算机检索PMedline(PubMed)、Embase、web of Science、Cochrane、wanted、CNKI、VIP并辅以手工检索,检索时限为建库至2019年9月发表的相关文章。比值比和相应的95%置信区间(95%CI)用于评估MTHFR C677T(rs1801394)和MTHFR A1298C(rs1801131)两种叶酸代谢基因突变与食管癌风险的关系。结果 MTHFR A1298C(rs1801131)变异基因型与食管癌发病率增加有相关性(CA vs.AA:OR=1.22,P0.05;CA+CC vs.AA:OR=1.18,P0.05)。MTHFR C677T(rs 1801133)变异基因型与食管癌风险增加无关。结论 MTHFR基因1298AC和CC基因型与食管癌发病有关。     

亚甲基四氢叶酸还原酶基因多态性及同型半胱氨酸水平与冠心病关系的研究

目的：探讨亚甲基四氢叶酸还原酶（MTHFR）C677T基因多态性、血清同型半胱氨酸（Hcy）水平与冠心病发生的关系。方法：收集解放军总医院第一附属医院收治的冠心病患者172例和健康体检者（正常对照组）160例的空腹静脉血,应用基因芯片技术联合检测MTHFR基因C677T多态性位点,并比较冠心病患者和健康体检者的MTHFR基因型及不同MTHFR基因型冠心病患者中血清Hcy水平的变化。结果：①冠心病组与正常对照组MTHFR基因C677T分布频率分别为CC型20.3%比32.5%（P〈0.05）、CT型44.8%比43.1%（P〉0.05）和TT型34.9%比24.3%（P〈0.05）;②冠心病组血清Hcy水平与正常对照组水平之间存在明显差异（P〈0.05）;③冠心病的TT基因型组的Hcy水平明显高于CC基因型组和CT基因型组,差异具有统计学意义（P〈0.05）。结论：冠心病组MTHFR C677T基因TT型分布频率及Hcy水平均高于正常对照组,MFHFR基因C677T TT型与冠心病的发生有关。     

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。     

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。     

瘢痕疙瘩人亚甲基四氢叶酸还原酶基因677及1298位点的突变

目的 探讨瘢痕疙瘩人亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase, MTHFR)基因677及1298位点的突变,以及对瘢痕疙瘩形成的作用.方法 收集瘢痕疙瘩标本20例,设患者自身静脉血标本为正常对照,提取基因组DNA,PCR扩增MTHFR基因677及1298位点片段,DNA测序,将测序结果与人类基因库(GenBank)比较.结果 20例瘢痕疙瘩标本中有17例被检测出677位点基因突变,突变率为85.0 % ( 17 /20),有13例被检测出1298位点基因突变,突变率为65.0 % ( 13/20 ).突变类型主要为点突变、插入、缺失,为多位点、多类型,呈多态性.正常对照静脉血标本中均未检出突变.结论 MTHFR基因677及1298位点突变与瘢痕疙瘩的发生有关.     

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.     

Hyperhomocysteinemia in children with renal transplants

Many studies have demonstrated a strong association between elevated plasma total homocysteine (tHcys) levels and vascular disease. The aim of the present study was to determine the plasma levels of tHcys in pediatric recipients of renal transplants, to establish possible correlations with renal function, lipid profile, and folate and vitamin B12 status, and to assess whether the C677T and A1298C polymorphisms in the 5, l0-methylenetetrahydrofolate reductase (MTHFR) gene were associated with a particular risk. A total of 26 transplanted children and adolescents were investigated. tHcys levels were elevated in transplanted patients (12.9+/-4.8 micro mol/l) and 73% of these displayed values above the 97th percentile of healthy children. Plasma tHcys correlated negatively with creatinine clearance ( r=-0.58, P<0.001) and plasma vitamin B(12) ( r=-0.40, P<0.05) and positively with plasma triglycerides ( r=0.53, P<0.005). No significant correlations were found between plasma tHcys level and age, gender, time elapsed after transplantation and plasma values of glucose, insulin, folic acid, total cholesterol, low-density lipoprotein-cholesterol, high-density lipoprotein-cholesterol, apolipoprotein B, and apolipoprotein A-1. Plasma tHcys level was clearly increased in 3 patients with a MTHFR 677TT/1298AA genotype. In a multiple stepwise regression model plasma creatinine and triglyceride levels and MTHFR 677TT/1298 AA genotype accounted for 60% of the observed plasma tHcys variability. The MTHFR 677CT/1298 AC genotype was not a significant predictor of tHcys plasma levels. We conclude that a moderate degree of hyperhomocysteinemia is often present in renal transplant children and that folate supplementation must be considered in this population.     

Effects of the C677T and A1298C polymorphisms of the MTHFR gene on the genetic predisposition for diabetic nephropathy.

BACKGROUND: Methylenetetrahydrofolate reductase (MTHFR) is a regulatory enzyme of homocysteine metabolism. The C677T polymorphism of the MTHFR gene has been reported to be associated with elevated plasma homocysteine in patients with low folic acid intake. A recently reported second common polymorphism, A1298C, may increase homocysteine, but only in individuals carrying the T677 allele. This study aimed to investigate the influence of the C677T and A1298C polymorphisms of the MTHFR gene on the development of diabetic nephropathy in Caucasian patients with type 2 diabetes. METHODS: We genotyped 429 type 2 diabetic patients for the C677T and A1298C polymorphisms using standard PCR-based protocols, and divided them into three groups based on renal status: 159 patients with normoalbuminuria, 149 with microalbuminuria, and 121 with persistent proteinuria and chronic renal failure (CRF). The C677T and A1298C genotype frequencies were compared among the three groups. RESULTS: Although the frequencies of the CT and TT genotypes of the C677T polymorphism tended to increase with each stage of diabetic nephropathy (53, 56 and 63% in normoalbuminuria, microalbuminuria and proteinuria/CRF, respectively), these differences were not significant. When male and female patients were analysed separately, the effect was seen only in males. The CT + TT genotype was present in 46% of male patients with normoalbuminuria, in 57% with microalbuminuria and in 68% with proteinuria/CRF (OR = 2.46; 95% CI 1.13-5.38). There were no differ-ences in the A1298C polymorphism among the three groups. CONCLUSIONS: These findings indicate that the C677T polymorphism is a risk factor for diabetic nephrop-athy in male patients with type 2 diabetes.     

The common mutations C677T and A1298C in the human methylenetetrahydrofolate reductase gene are associated with hyperhomocysteinemia and cardiovascular disease in hemodialysis patients

BACKGROUND: Plasma total homocysteine (tHcy) level might be an important risk factor for the development of cardiovascular disease (CVD) in dialysis patients. While both renal failure and mutations of the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene may result in hyperhomocysteinemia and CVD, the distinct roles of the thermolabile MTHFR mutation at nucleotide C677T and the more recently described mutation at nucleotide A1298C have not been evaluated concurrently in patients on hemodialysis. METHODS: A cross-sectional study was performed in 120 maintenance HD patients to determine the prevalence of MTHFR C677T and A1298C mutations and their relative association to hyperhomocysteinemia and CVD. RESULTS: Both mutations, the C677T and the A1298C, were highly prevalent in HD patients with allele frequencies of 0.41 and 0.27, respectively. The prevalence of CVD in HD patients was 55% and its significant risk factors included, in descending order, hyperhomocysteinemia, MTHFR C677T mutation, low serum folate levels, diabetes mellitus, hypertension, and double heterozygote state for both MTHFR mutations (677CT/1298AC). MTHFR A1298C mutation alone and gender were not associated with either hyperhomocysteinemia or increased CVD risk, but the HD patients with homozygotes 1298CC and wild alleles 677CC (677CC/1298CC) have significant increase of tHcy (37.7 +/- 12) and high prevalence of CVD. CONCLUSIONS: Hyperhomocysteinemia, serum folate levels and both C677T and A1298C MTHFR mutations are associated with CVD in HD patients.     

Effect of high dose folic acid therapy on hyperhomocysteinemia in hemodialysis patients: results of the Vienna multicenter study

Homocysteine is associated with atherosclerosis and enhanced cardiovascular risk. In previous studies, treatment with folic acid up to 15 mg/d failed to correct hyperhomocysteinemia in the majority of end-stage renal disease patients. A dose of 30 or 60 mg of folic acid per day was compared with 15 mg/d in an attempt to normalize hyperhomocysteinemia in 150 hemodialysis patients. In a randomized, double-blind, multicenter study, 144 patients completed the 4-wk treatment period and 121 patients completed the 6-mo follow-up. Total homocysteine plasma levels were reduced by 32.1% (15 mg/d), 29. 9% (30 mg/d), or 37.8% (60 mg/d) with no significant differences found between the three treatment groups. Baseline total homocysteine plasma concentration was an independent predictor of the response to folic acid therapy (P = 0.0001), whereas the 5, 10-methylenetetrahydrofolate reductase polymorphisms (MTHFR 677C --> T and 1298A --> C) had no influence. Nevertheless, patients with the MTHFR 677TT genotype more frequently attained normal total homocysteine plasma levels than patients with the CC or CT genotype (P = 0.025). In response to 60 mg of folic acid per day, TT genotype patients had lower folate plasma levels compared to CC or CT genotype patients (P = 0.016). After completion of the 4-wk treatment period with 30 or 60 mg of folic acid per day, there was a marked rebound of total homocysteine plasma levels at the end of the follow-up in patients with the MTHFR 677TT genotype, which even exceeded baseline values in several patients (P = 0.0001). This study clearly demonstrates that doses of 30 or 60 mg of folic acid per day are not more effective than 15 mg/d in reducing hyperhomocysteinemia in regular hemodialysis patients. Patients with the MTHFR 677TT genotype are more likely to realize normal total homocysteine plasma levels. Folic acid at 30 or 60 mg/d but not 15 mg/d results in a rebound of total homocysteine plasma concentrations when treatment is stopped.     

Association of methylenetetrahydrofolate reductase genetic polymorphisms with atlantoaxial dislocation

OBJECT: Genetic mechanisms of atlantoaxial dislocation (AAD) have not previously been elucidated. The authors studied association of polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene, which encodes enzymes of the folate pathway (implicated in causation of neural tube defects [NTDs]), in patients with AAD. METHODS: Molecular analysis of MTHFR polymorphisms (677C-->T, cytosine to thymine and, 1298A-->C, adenine to cytosine, substitutions) was carried out using polymerase chain reaction and restriction enzyme digestion in 75 consecutive patients with AAD and in their reducible (nine patients, 12%) and irreducible (66 patients, 88%) subgroups. Controls were 60 age- and sex-matched patients of the same ethnicity. Comparisons of genotype and allele frequencies were performed using a chi-square test (with significance at p < 0.05). RESULTS: The CT genotype frequency of MTHFR 677C-->T polymorphism was significantly increased in the full group of patients with AAD (odds ratio [OR] 3.00, 95% confidence interval [CI] 1.28-7.14, p = 0.005) as well as in the irreducible subgroup (OR 2.81, 95% CI 1.17-6.86, p = 0.01). The frequency of T alleles was also higher in the AAD group (25.3%) than in controls (15%). The comparison of the combined frequency of CT and TT genotypes with the frequency of the CC genotype again showed significant association in AAD (OR 2.63, 95% CI 1.98-5.90, p = 0.009) and the irreducible (OR 2.5, 95% CI 1.1-5.74, p = 0.016) subgroup. There was, however, no significant association of MTHFR 1298A-->C polymorphism with AAD. CONCLUSIONS: Both MTHFR 677C-->T polymorphism and higher T allele frequency have significant associations with AAD, especially the irreducible variety. Perhaps adequate supplementation of periconceptional folic acid to circumvent effects of this missense mutation (as is done for prevention of NTDs) would reduce the incidence of AAD.     

Molecular biology of 5,10-methylenetetrahydrofolate reductase

Methylenetetrahydrofolate reductase (MTHFR) plays a central role in the folate cycle and contributes to the metabolism of the amino acid homocysteine. It catalyzes the reduction of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, thus generating the active form of folate required for remethylation of homocysteine to methionine. Deficiency of MTHFR may be associated with an increase in plasma homocysteine, which in turn is associated with an increased risk of vascular disease. This article summarizes the biochemistry, the function in the folate cycle, and the molecular genetics of this enzyme. Particular emphasis has been given to the role of two common polymorphisms (MTHFR 677C-->T, 1298A-->C) in cardiovascular disease, cerebrovascular disease, venous thrombosis, longevity, neural tube defects, pregnancy/preeclampsia, diabetes, cancer, psychiatry, renal failure and renal replacement therapy. Finally, the rare genetic defects underlying severe MTHFR deficiency are also considered.     

Effects of the glutamate carboxypeptidase II (GCP2 1561C>T) and reduced folate carrier (RFC1 80G>A) allelic variants on folate and total homocysteine levels in kidney transplant patients

BACKGROUND: The effect of the glutamate carboxypeptidase II GCP2 1561C>T and the reduced folate carrier 1 RFC1 80G>A polymorphisms on folate and total homocysteine (tHcy) plasma levels of kidney transplant patients are unknown. METHODS: In a cross-sectional study of 730 kidney allograft recipients, GCP2 1561C>T, RFC1 80G>A, folate, and tHcy plasma levels were analyzed using linear regression models that allowed dependent covariates to follow a gamma distribution for univariate and multivariate analyses. RESULTS: The allele frequency for GCP2 1561C>T was 0.05, and 0.43 for RFC1 80G>A. Heterozygosity or homozygosity for GCP2 1561C>T was associated with higher folate plasma levels compared to patients without mutation (P < 0.0001), while RFC1 80G>A showed no influence. Multiple testing, also including MTHFR 677C>T and MTHFR 1298A>C, revealed no interaction between the different genotypes and the folate plasma concentration. Neither GCP2 1561C>T nor RFC1 80G>A showed an association with tHcy plasma levels. CONCLUSION: We conclude that GCP2 1561C>T is associated with elevated folate levels. GCP2 1561C>T and RFC1 80G>A are no major determinants of tHcy plasma levels in kidney transplant patients.     

Influence of Methylenetetrahydrofolate Reductase Gene Polymorphisms on Homocysteine Concentrations after Nitrous Oxide Anesthesia

Background: Mutations in the methylenetetrahydrofolate reductase (MTHFR) gene (677C>T, 1298A>C) cause elevated plasma homocysteine concentrations and have been linked to fatal outcomes after nitrous oxide anesthesia. This study tested the hypothesis that patients with common MTHFR 677C>T or 1298A>C mutations develop higher plasma homocysteine concentrations after nitrous oxide anesthesia than wild-type patients.

Methods: In this prospective, observational cohort study with blinded, mendelian randomization, the authors included 140 healthy patients undergoing elective surgery. All patients received 66% nitrous oxide for at least 2 h. The main outcome variable, plasma total homocysteine, and folate, vitamin B12, and holotranscobalamin II were measured before, during, and after surgery. After completion of the study, all patients were tested for their MTHFR 677C>T or 1298A>C genotype.

Results: Patients with a homozygous MTHFR 677C>T or 1298A>C mutation (n = 25) developed higher plasma homocysteine concentrations (median [interquartile range], 14.9 [10.0-26.4] [mu]m) than wild-type or heterozygous patients (9.3 [7.5-15.5] [mu]m; n = 115). The change in homocysteine after nitrous oxide anesthesia was tripled in homozygous patients compared with wild-type (5.6 [mu]m [+60%] vs. 1.8 [mu]m [+22%]). Only homozygous patients reached average homocysteine levels considered abnormal (> 15 [mu]m). Plasma 5-methyl-tetrahydrofolate concentrations increased uniformly by 20% after nitrous oxide anesthesia, indicating the inactivation of methionine synthase and subsequent folate trapping. Holotranscobalamin II concentrations remained unchanged, indicating no effect of nitrous oxide on vitamin B12 plasma concentrations.