山东地区非综合征性唇腭裂患者MTHFR基因C677T的多态性研究

目的探讨山东地区亚甲基四氢叶酸还原酶（MTHFR）基因C677T的多态性与非综合征性唇腭裂（NSCL/P）的关系。方法运用聚合酶链反应-限制性内切酶片段长度多态性分析技术（PCR-RFLP）,对2006年8月至2008年8月曾在齐鲁医院治疗的来自山东地区NSCL/P患儿35例和健康查体的正常儿童51例MTHFR基因的C677T基因型检测分析。结果患者组与对照组的基因型构成比有统计学意义（χ^2=8.770,P=0.0121）。对T分析,计算得到携带T等位基因的儿童患非综合征性唇腭裂的危险性是不携带T等位基因儿童的2.568倍（OR=2.568,95%CI：1.324-4.979）。TT突变纯合子患非综合征性唇腭裂的危险性是非TT纯合子的3.095倍（OR=6.088,95%CI：1.240-7.722）。结论 MTHFRC677T的T等位基因可能是山东地区非综合征性唇腭裂的遗传风险因子。     

山东地区非综合征性唇腭裂患者MTHFR基因C677T的多态性研究

目的探讨山东地区亚甲基四氢叶酸还原酶(MTHFR)基因C677T的多态性与非综合征性唇腭裂(NSCL/P)的关系。方法运用聚合酶链反应-限制性内切酶片段长度多态性分析技术(PCR-RFLP),对2006年8月至2008年8月曾在齐鲁医院治疗的来自山东地区NSCL/P患儿35例和健康查体的正常儿童51例MTHFR基因的C677T基因型检测分析。结果患者组与对照组的基因型构成比有统计学意义(χ2=8.770,P=0.0121)。对T分析,计算得到携带T等位基因的儿童患非综合征性唇腭裂的危险性是不携带T等位基因儿童的2.568倍(OR=2.568,95%CI:1.324-4.979)。TT突变纯合子患非综合征性唇腭裂的危险性是非TT纯合子的3.095倍(OR=6.088,95%CI:1.240-7.722)。结论 MTHFRC677T的T等位基因可能是山东地区非综合征性唇腭裂的遗传风险因子。     

青岛地区汉族育龄妇女亚甲基四氢叶酸还原酶基因667位点多态性分布研究

目的探讨亚甲基四氢叶酸还原酶（MTHFR）基因667位点多态性在青岛市汉族育龄妇女中的分布状况。方法用聚合酶链反应-限制性片段长度多态性（PCR-RFLP）技术检测98份育龄妇女外周血MTHFR C667T基因型分布。结果本研究人群MTHFR 677位点基因的CC、CT、TT基因型频率分别为24.5%、53.1%、22.4%,T等位基因频率为0.49。结论青岛市汉族育龄妇女MTHFR基因667位点多态性与其他地区有较大不同,调查可以为相关研究提供相应的分子生物学依据。     

亚甲基四氢叶酸还原酶基因多态性与青海汉族妊娠期高血压疾病的相关性

目的 探讨亚甲基四氢叶酸还原酶（MTHFR）基因-677C/T（rs1801133）多态性与青海汉族妇女妊娠期高血压疾病（HDP）的相关性。 方法 选择青海省HDP患者 139 例（HDP组）,正常妊娠孕妇 145 例（对照组）,应用限制性内切酶片段长度多态性聚合酶链反应（PCR-RFLP）方法,检测HDP组和对照组MTHFR-677C/T多态性分型并测序验证。 结果 HDP组和对照组MTHFR基因CC、CT、TT基因型频率分别为54.68%、35.25%、10.07% 和69.66%、22.06%、8.28%,CC基因型频率HDP组54.68%低于对照组69.66%（P<0.05）,CT基因型频率HDP组35.25%高于对照组22.06%（P<0.05）,而TT基因型频率HDP组和对照组之间差异无统计学意义（P>0.05）;HDP组和对照组MTHFR-677C/T多态性C和T等位基因频率分布有差异（P<0.05）,HDP组T等位基因频率高于对照组（χ²=5.568,P<0.05）。 结论 MTHFR基因-677C/T多态性与青海汉族HDP相关,MTHFR基因-677C/T多态性中T等位基因可能是HDP的易感基因,CT基因型为HDP的易感基因型。     

贵州荔波汉族与雷山苗族MTHFR基因多态性分布的比较

目的比较贵州汉族、苗族亚甲基四氢叶酸还原酶基因(MTHFR)多态性的分布情况,获取 MTHFR C677T和A1298C位点的群体遗传学数据.方法应用PCR-RLFP技术调查了贵州荔波汉族及雷山苗族MTHFR基因型的分布.结果汉族MTHFR 677位T等位基因频率为22.7%低于中国北方汉族,与苗族(10.64%)差异有显著性.苗族1298位C等位基因频率为48.66%高于有文献报道的种族和民族,与汉族(28.85%)差异有显著性.677TT/1298CC双杂合子的分布频率分别是16.66%,11.11%.在苗族还发现一例677TT/1298CC双纯合子.结论 MTHFR两个位点多态性在贵州汉族和苗族有民族差异;苗族A1298C位点C等位基因频率是有文献报道最高的民族.     

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。     

重型抑郁症患者亚甲基四氢叶酸还原酶基因多态性检测

目的 探讨北方汉族人群5,10-亚甲基四氢叶酸还原酶基因多态性与重型抑郁症的关系。方法 采用病例-对照研究。聚合酶链反应-限制性片段长度多态性技术检测MTHFR C677T及 A1298C基因多态性。结果 （1）对照组677TT基因型频率及T等位基因频率分别为为13.16％和39.80%;1298CC基因型和C等位基因频率分别为1.32%和12.83％;（2）抑郁症组MTHFR 677TT基因型频率（35.53％）明显高于正常对照组（13.16％）（P＜0.001）,677 T等位基因频率（57.24%）明显高于对照组（39.80%）（P＜0.001）。（3）Ligistic回归分析, C677T基因型与疾病的发生有关（P<0.001）。结论MTHFR C677T基因变异与本组重症抑郁症发病有关,是其发病的危险因素;MTHFR A1298C基因变异与本组重症抑郁症发病无关联。     

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。     

新余市汉族女性MTHFR与MTRR基因多态性分布研究

目的针对新余市汉族女性开展分子流行病学调查,研究叶酸代谢关键酶甲硫氨酸合成酶还原酶(MTRR)和5,10-亚甲基四氢叶酸还原酶(MTHFR)的基因多态性分布。方法以孕期保健的521名汉族健康女性为研究对象,采集口腔黏膜上皮脱落细胞,提取基因组DNA,使用荧光定量PCR方法检测MTHFR C677T、A1298C和MTRR A66G基因多态性,进行统计分析。结果 (1)入组对象的基因多态性分布符合遗传平衡。(2)汉族女性MTHFR 677CC、CT、TT的基因型频率分别为38.6%、47.6%、13.8%,C、T等位基因频率分别为62.4%、37.6%;MTHFR 1298AA、AC、CC的基因型频率分别为65.1%、31.9%、3.07%,A、C等位基因频率分别为81.0%、19.0%;MTRR 66AA、AG、GG的基因型频率分别为60.3%、35.1%、4.61%,A、G等位基因频率分别为77.8%、22.2%。(3)汉族女性MTHFR C677T和A1298C两位点连锁有7种组合,频率最高的是CT/AA(30.5%),没有TT/AC和TT/CC组合。两位点间存在完全连锁不平衡(D'=1.0,r~2=0.124)。结论获取新余市汉族女性MTHFR和MTRR基因多态性的群体遗传学特征,其中关键基因位点MTHFR C677T的高风险TT基因型比例为13.8%,低于已报道的山东淄博、河南新乡、辽宁沈阳等地,高于广东佛山市,说明叶酸利用能力中等,对于高风险人群还需加强孕期管理,同时本研究也为当地人群进行个体化增补叶酸提供理论依据。     

母亲叶酸代谢相关基因多态性与唐氏综合征发生的关系

目的研究叶酸代谢相关基因多态性在浙南地区汉族妇女中的分布,探讨其与唐氏综合征(Down’s Syn-drome,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(MTHFR)基因C677T、A1298C位点;甲硫氨酸合成酶(MTR)基因A2756G位点单核苷酸多态性。结果 MTHFR 677 T基因及CT、TT基因型、MTHFR 1298 C基因及AC、CC基因型、MTR 2756 G基因及AG基因型频率观察组与对照组比较均无统计学意义(P>0.05)。三个位点基因型频率联合分析两组也不存在统计学意义(OR=0.692,P>0.05)。结论浙南地区汉族妇女MTHFR C677T、FTHFR A1298C、MTR A2756G基因型不是DS发生的风险因素;三个基因型的联合频率也未见增加DS发生的风险。     

郑州市中原区汉族育龄女性MTHFR和MTRR基因多态性

目的利用基因检测技术筛查出育龄女性叶酸利用能力差的高风险人群,指导育龄女性合理补充叶酸。方法通过荧光定量PCR,对2017年12月至2018年10月采集的2652例郑州市中原区育龄女性进行5,10-亚甲基四氢叶酸还原酶(MTHFR)C667T、A1298C位点和甲硫氨酸合酶还原酶(MTRR)A66G位点的基因型测定,并与其他地区人群基因型和等位基因频率分布进行比较,然后根据基因型综合判断育龄女性叶酸代谢能力强弱,由此得出育龄女性是否有叶酸补充风险及风险级别。结果检测的MTHFR C667T位点中,野生型(CC)、杂合突变型(CT)及纯合突变型(TT)分别占15.05%、46.60%和38.35%,突变基因T的基因频率为61.65%;不同年龄组(≤30和>30岁)均以杂合突变型为主。MTHFR A1298C位点中分别为74.55%、23.49%和1.96%,突变基因C的基因频率为13.71%;不同年龄组(≤30和>30岁)均以野生型为主。MTRR A66G位点中分别为57.43%、36.73%和5.84%,突变基因G的基因频率为24.21%;不同年龄组(≤30和>30岁)均以野生型为主。结论郑州地区育龄女性MTHFR C677T基因多态性分布与地域有相关性,超过50%以上的育龄女性携带高风险基因。因此,对叶酸代谢基因多态性检测高风险孕妇合理增补叶酸剂量,可进一步降低新生儿出生缺陷。     

C677T variant form at the MTHFR gene and CL/P: A risk factor for mothers?

Maternal folic acid supplementation in early pregnancy has been suggested to play a role in the prevention of nonsyndromic orofacial cleft, i.e., cleft lip with or without cleft palate (CL/P). Moreover, some authors demonstrated association of the C→T mutation (C677T), converting an alanine to a valine residue in 5,10‐methylenetetrahydrofolate reductase (MTHFR) gene, with other congenital anomalies such as neural tube defects (NTDs). Because of MTHFR’s involvement in the metabolism of folate, we investigated 64 CL/P patients and their parents for C677T MTHFR mutation. No linkage disequilibrium was found using the transmission disequilibrium test (TDT). However, a significantly higher mutation frequency was detected in mothers of CL/P patients compared to controls. The odds ratios calculated for mothers having CT or TT genotype, compared to the normal CC genotype, were 2.75 (95% confidence interval 1.30–5.57) and 2.51 (1.00–6.14), respectively. These results support the involvement of the folate pathway in the etiology of CL/P, and indicate an effect of the maternal genotype, rather than influence of the embryo’s genotype. © 2001 Wiley‐Liss, Inc.     

C677T variant form at the MTHFR gene and CL/P: a risk factor for mothers?

Maternal folic acid supplementation in early pregnancy has been suggested to play a role in the prevention of nonsyndromic orofacial cleft, i.e., cleft lip with or without cleft palate (CL/P). Moreover, some authors demonstrated association of the C-->T mutation (C677T), converting an alanine to a valine residue in 5,10-methylenetetrahydrofolate reductase (MTHFR) gene, with other congenital anomalies such as neural tube defects (NTDs). Because of MTHFR's involvement in the metabolism of folate, we investigated 64 CL/P patients and their parents for C677T MTHFR mutation. No linkage disequilibrium was found using the transmission disequilibrium test (TDT). However, a significantly higher mutation frequency was detected in mothers of CL/P patients compared to controls. The odds ratios calculated for mothers having CT or TT genotype, compared to the normal CC genotype, were 2.75 (95% confidence interval 1.30-5.57) and 2.51 (1.00-6.14), respectively. These results support the involvement of the folate pathway in the etiology of CL/P, and indicate an effect of the maternal genotype, rather than influence of the embryo's genotype.     

Variable contribution of the MTHFR C677T polymorphism to non-syndromic cleft lip and palate risk in China

Non-syndromic cleft lip with or without cleft palate (nsCL/P) is one of the most common craniofacial malformations among newborn infants. It has been demonstrated that periconceptional folic acid supplementation may reduce the occurrence of offspring with clefts, particularly in the North China; however, the mechanism remains unknown. Our study of a thermolabile polymorphism (C677T) of methylenetetrahydrofolate reductase (MTHFR) gene in 170 Chinese case-parent triads revealed a moderate association between this MTHFR polymorphism and nsCL/P in a population from North China, but not in a population from South China. Moreover, the study revealed that the heterozygous parents in the North were about twice as likely to transmit the high-risk T allele to affected cases, as that observed in the South (OR = 2.24, 95% CI: 1.08-4.65). Thus, the MTHFR polymorphism is a significant risk factor for nsCL/P in this Northern Chinese population. Our study suggested possible genetic heterogeneity in the development of nsCL/P among Northern and Southern populations in China.     

Polymorphisms of methylenetetrahydrofolate reductase gene among women of childbearing age from Shiyan areaCSCD

Objective: To assess the association of methylenetetrahydrofolate reductase (MTHFR) gene 677C>T polymorphism with blood homocysteine (Hey) level among women of childbearing age from Shiyan area. Methods: PCR - chip hybridization was used to determine the genotype of MTHFR 6770T, and a biochemical assay was used to determine the total Hey level among 428 healthy women of childbearing age. Association of MTHFR 677>T with total Hey level was assessed. Results: Heterozygous CT mutation was most common form for the MTHFR 677>T polymorphisms and amounted for 49. 77% among the group, while the CC wild type and homozygous TT mutation respectively accounted for 30. 61% and 19. 63%. These gave a frequency of 44. 51% for the 677T allele. The dominant genotype among different age groups were the CT type. Of note, the proportion of MTHFR 677CC is higher in women above 30 years of age. The distribution of MTHFR 677>T genotypes has differed significantly among different age groups (P<0. 05). Compared with those with wild type alleles, carriers of MTHFR mutations had a higher plasma Hey level. The genotypic frequencies of MTHFR C677T in Shiyan region differed significantly from those of Sichuan, Hebei, Henan and Shandong (P < 0. 05) but were similar to those of Jiangsu, Guangdong, Ningxia and Xinjiang. Conclusion: The distribution of MTHFR C677T polymorphism among women of childbearing age in Shiyan area is influenced by age and is geographically specific and associated with plasma Hey level. Nearly 50% of women have carried the high risk alleles, for whom folic acid supplementation is crucial for the reduction of birth defect rate. © 2018 MeDitorial Ltd. All rights reserved.     

Infant C677T mutation in MTHFR,maternal periconceptional vitamin use,and cleft lip

Studies have reported an association between homozygosity for a variant form of the methylenetetrahydrofolate reductase (MTHFR) gene and risk for neural tube defects. Because of MTHFR's involvement with folate metabolism and evidence that maternal use of a multivitamin with folic acid in early pregnancy reduces risk for cleft lip with or without cleft palate (CLP), we hypothesized that infants homozygous for the C677T genotype would be at increased risk for CLP because of lower MTHFR enzymatic activity. Data were derived from a large population-based, case-control study of fetuses and liveborn infants among a cohort of 1987 to 1989 California births. The analyses involved 310 infants with isolated CLP whose mothers completed a telephone interview and whose DNA was available from newborn screening blood specimens and involved 383 control infants without a congenital anomaly whose mothers completed a telephone interview and whose DNA was available. Cases and controls were genotyped TT if homozygous for the C677T allele, CT if heterozygous for the C677T allele, and CC if homozygous for the C677 (wild-type) allele. Odds ratios for CLP were 0.89 (0.55 to 1.4) and 0.78 (0.56 to 1.1) for infants with TT versus CC and infants with CT versus CC genotypes, respectively. Compared with the CC genotype, the odds ratios for CLP among infants with the TT genotype were 0.74 (0.39 to 1.4) for those infants whose mothers were users and 1.4 (0.54 to 3.6) for those infants whose mothers were not users of multivitamins containing folic acid periconceptionally. The two estimates were not statistically heterogeneous (P = 0.30). Our results did not indicate increased risks for CLP among infants homozygous for the C677T genotype, nor do they indicate an interaction between infant C677T genotype and maternal multivitamin use on the occurrence of CLP. Am. J. Med. Genet. 80:196–198, 1998. © 1998 Wiley-Liss, Inc.     

Increased frequency of combined methylenetetrahydrofolate reductase C677T and A1298C mutated alleles in spontaneously aborted embryos

The pathogenesis of spontaneous abortion is complex, presumably involving the interaction of several genetic and environmental factors. The methylenetetrahydrofolate reductase (MTHFR) gene C677T and A1298C polymorphisms are commonly associated with defects in folate dependent homocysteine metabolism and have been implicated as risk factors for recurrent embryo loss in early pregnancy. In the present study we have determined the prevalence of combined MTHFR C677T and A1298C polymorphisms in DNA samples from spontaneously aborted embryos (foetal death between sixth and twentieth week after conception) and adult controls using solid-phase minisequencing technique. There was a significant odds ratio of 14.2 (95% CI 1.78-113) in spontaneously aborted embryos comparing the prevalence of one or more 677T and 1298C alleles vs the wild type combined genotype (677CC/1298AA), indicating that the MTHFR polymorphisms may have a major impact on foetal survival. Combined 677CT/1298CC, 677TT/1298AC or 677TT/1298CC genotypes, which contain three or four mutant alleles, were not detected in any of the groups, suggesting complete linkage disequilibrium between the two polymorphisms. The present finding of high prevalence of mutated MTHFR genotypes in spontaneously aborted embryos emphasises the potential protective role of periconceptional folic acid supplementation.     

Maternal homozygosity for the common MTHFR mutation as a potential risk factor for offspring with limb defects

A common mutation, C677T, in the 5,10-methylenetetrahydrofolate reductase (MTHFR) gene leads to altered homocysteine metabolism, and has been associated with the occurrence of neural tube defects (NTD). Administration of folic acid decreases this risk. There is also evidence that periconceptional supplementation of mothers with folic acid can decrease the risk of limb defects in the offspring. Here we describe a child with a transverse terminal defect of one hand, whose mother is homozygous for the C677T MTHFR mutation. We suggest that homozygosity for the MTHFR mutation may be a risk factor for transverse terminal limb defect/s by an effect mediated through altered folate and homocysteine metabolism. Further studies of mothers of infants with limb reduction defects for the MTHFR mutation may be of help in establishing this association. A simple intervention in the form of folic acid supplementation would be protective, should an association be established.     

TaqMan探针实时PCR检测人MTHFR基因C677T多态性方法的建立

目的建立TaqMan探针实时PCR检测人MTHFR基因C677T多态性的方法。方法设计一对MTHFR基因C677T多态位点的引物及TaqMan探针,采用TaqMan探针实时PCR扩增SNP分型方法检测唇腭裂患者及其父母共100人的MTHFR基因C677T多态性,与常规PCR-RFLP方法进行一致率比较,并对其特异性、敏感性和重复性以及成本-效益等进行评价,同时对部分实时PCR产物样本进行测序验证。结果运用TaqMan探针实时荧光PCR技术对MTHFR基因C677T多态性检测结果准确,特异性好,与常规PCR-RFLP方法结果具有高度一致性,Kappa=0.922>0.75(P=0.000);检测灵敏度可达2×103拷贝;重复性好、高通量、无污染、安全性好;随机样品TaqMan探针分型结果与测序结果完全一致。结论成功建立了TaqMan探针实时PCR检测人MTHFR基因C677T多态性的方法;此方法是常规临床诊断及大规模群体研究的良好平台。     

MTHFR、MTRR基因多态性与反复流产的相关性分析

目的探讨叶酸代谢相关基因5,10-亚甲基四氢叶酸还原酶(MTHFR)、甲硫氨酸合成酶还原酶(MTRR)多态性与反复流产的关系,分析基因多态性对红细胞叶酸水平的影响。方法选取2016年12月至2018年6月来唐山市妇幼保健院遗传咨询门诊,要求进行常规孕前检查,汉族非妊娠健康女性424例为研究对象。依据不良孕产史分为两组,其中病例组216例和对照组218例。采集静脉血,提取DNA,荧光定量PCR法进行MTHFR、MTRR基因多态性检测。化学发光法进行红细胞叶酸定量检测。采用SPSS19.0软件进行统计学分析。比较两组MTHFR、MTRR基因多态性分布频率、不同基因类型红细胞叶酸水平。探讨基因多态性、红细胞叶酸水平与反复流产的关系。结果MTHFR A1298C和MTRR A66G两位点多态性在病例组和对照组间的分布,差异无统计学意义。MTHFR C677T位点多态性,在病例组中的分布频率明显高于对照组,差异具有统计学意义。病例组中MTHFR C667T位点TT型基因突变的患者红细胞叶酸水平远低于正常和杂合型。结论MTHFR C677T基因突变与反复流产的密切相关,MTHFR C667T位点TT型基因突变影响机体红细胞叶酸代谢水平。