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.     

贵州苗族CBS基因与MTHFR基因多态性研究

目的对贵州雷山西江苗族胱硫醚合酶（cystathionine beta-synthase,CBS）基因与亚甲基四氢叶酸还原酶（methylenetetrahydrofolate reductase,MTHFR）基因多态性进行研究。方法采用PCR-限制性片断长度多态性（PCR-RFLP）、PCR-变性梯度凝胶电泳（PCR-DGGE）-基因测序（Gene sequenceing）的方法检测贵州雷山西江苗族CBS基因与MTHFR基因的基因频率及基因型的分布。结果CBS基因的699C→T等位基因频率为5.6%、833 T→C等位基因频率为29.4%。MTHFR基因的677C→T等位基因频率为10.64%、1298 A→C等位基因频率为48.66%。结论同一民族,胱硫醚合酶基因与亚甲基四氢叶酸还原酶基因存在群体差异,这种群体差异可能与人群对多种疾病的群体易感性有关。     

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。     

贵州省荔波县汉族和布依族女性MTHFR与MTRR多态性的分布

目的针对贵州省荔波县汉族和布依族女性开展分子流行病学调查,研究叶酸代谢关键酶亚甲基四氢叶酸还原酶(MTHFR)和甲硫氨酸合成酶还原酶(MTRR)的基因多态性分布。方法以在荔波县人民医院进行围孕期保健的1 342名健康女性为研究对象,其中汉族236人、布依族1 106人。采集口腔黏膜上皮脱落细胞,抽提基因组DNA,使用荧光定量PCR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和TT的基因型频率分别为49.6%、39.8%和10.6%,布依族女性为61.8%、33.7%和4.4%;汉族女性MTHFR 1298AA、AC和CC的基因型频率分别为62.3%、33.1%和4.7%,布依族女性为47.4%、42.9%和9.7%,两位点均有差异(P0.05)。汉族女性MTRR 66AA、AG和GG的基因型频率分别为56.4%、37.4%和5.9%,布依族女性为57.0%、36.0%和7.1%,差异无统计学意义。3)汉族和布依族女性MTHFR C677T与A1298C两位点连锁均有6种组合,没有CT/CC、TT/AC和TT/CC。汉族女性频率最高的是CT/AA,布依族女性频率最高的是CC/AC。两个位点构建的单倍型存在CA、TA和CC 3种组合,两位点间存在完全连锁不平衡。结论获取荔波县汉族和布依族女性MTHFR与MTRR多态性的群体遗传学特征,为指导科学增补叶酸营养、实施个性化孕期保健提供依据。     

河源地区汉族女性MTHFR基因多态性调查及其与血清HCY水平相关性的研究

目的调查广东省河源地区汉族女性5,10-亚甲基四氢叶酸还原酶(MTHFR)C677T、A1298C位点基因多态性分布特征,研究分析遗传因素与血清同型半胱氨酸(HCY)的相关性,为本地区育龄妇女个性化补服叶酸及出生缺陷的一级预防提供依据。方法以该地区1423位汉族女性为研究对象,检测其MTHFR C677T、A1298C基因位点多态性,与我国其他南北各地区既有数据对比,采用统计学方法分析基因的多态性分布特征;对其中418位孕期女性测定血清同型半胱氨酸浓度,分析该生化指标与遗传因素的相关性。结果本地区的汉族女性MTHFR 677TT基因型频率(7.4%),MTHFR 1298CC基因型频率(5.6%)。C677T和A1298C位点三种基因型间血清HCY水平差异无统计学意义(P0.05)。结论本地区汉族女性MTHFR基因C677T、A1298C位点多态性分布特征有其自身的特点;基因位点的多态性变化对血清同型半胱氨酸水平无显著性影响。     

张家港市汉族女性MTHFR与MTRR基因多态性分布

目的探讨张家港市汉族女性MTHFR、MTRR基因多态性的频率特征,以指导孕妇增补叶酸和出生缺陷一级预防。方法以张家港市4008例汉族女性为研究对象,检测MTHFR C677T、A1298C和MTRR A66G的基因分型。统计分析基因多态性的频率特征,并与已报道的其他地区汉族女性的数据进行比较。结果张家港市汉族女性的MTHFR C677T位点CC、CT和TT基因型频率分别为32.2%、49.5%和18.3%。C等位基因频率为64.3%,T等位基因频率为35.7%。MTHFR A1298C位AA、AC和CC基因型频率分别为68.7%、28.7%和2.5%。A等位基因频率为80.8%,C等位基因频率为19.2%。MTRR A66G位点AA、AG和GG基因型频率分别为54.4%、38.5%和7.1%。A等位基因频率为76.3%,G等位基因频率为26.4%。结论张家港市汉族女性MTHFR和MTRR基因多态性频率具有地域特异性。     

MTHFR基因多态性与银屑病的遗传易感性

【摘要】　目的　探讨亚甲基四氢叶酸还原酶(methylenetetrahydrofolate reductase,MTHFR)基因单核苷酸多态与中国北方地区银屑病的关系。方法　针对123例寻常型银屑病患者和129名正常对照个体,分别用PCR-RFLP和AS-PCR的方法,分析C677T、G1793A和A1298C 3个多态位点基因型,并进行统计分析。 结果 在病例组中,MTHFR 677 C、T等位基因频率分别为45.13%、54.87%,1298A、C等位基因频率为88.37%、11.63%,1793G、A等位基因频率为95.12%、4.88%。在正常对照组中,677 C、T等位基因频率分别为44.96%、54.87%,1298A、C等位基因频率为86.44%、13.56%,1793G、A等位基因频率为96.12%、3.88%。经统计学分析,MTHFR C677T 、A1298C、G1793A 各多态位点基因型、等位基因频率在病例组和对照组中的分布差异无显著性意义,C677T与A1298C基因型联合分析也未发现有统计学意义。结论 MTHFR基因的3个多态位点（C677T、A1298C、G1793A）与寻常型银屑病无明显的相关关系,可能与寻常型银屑病的易感性无关。     

麻城地区汉族育龄女性MTHFR、MTRR基因多态性分析

目的分析麻城市汉族育龄女性MTHFR、MTRR基因多态性的分布特征,了解本市MTHFR、MTRR基因遗传特点,以期为育龄女性提供科学的叶酸补服方案。方法采用横断面调查研究方法,以2017年10月-2018年12月到麻城市妇幼保健院做孕检的汉族女性355人为研究对象。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,并与已报道地区进行比较,为进一步降低出生缺陷及孕产妇疾病提供分子医学理论依据。结果麻城市汉族族女性MTHFR C677T、A1298C基因型和等位基因频率分布与已有相关数据报道的延边市、济源市汉族女性比较,有显著性差异(P0.01);MTHFRA1298C基因型和等位基因频率与廊坊市汉族女性比较,差异有统计学意义(P0.05);MTHFRC677T基因型和等位基因频率与南宁市、琼海市、惠州汉族女性比较,有统计学意义(P0.05);而麻城市汉族女性MTHFRC677T,A1298C和MTRRA66G基因型和等位基因频率与郫县、英山县、昆明市汉族女性比较,差异无统计学意义(P0.05)。结论麻城市汉族女性的MTHFR、MTRR基因频率分布有自身特点。     

建始地区汉族女性叶酸代谢通路关键酶基因MTHFR、MTRR单核苷酸多态性分布特征调查

目的调查湖北省建始县汉族女性叶酸代谢障碍关键酶基因5,10-亚甲基四氢叶酸还原酶(MTHFR)C677T、A1298C及甲硫氨酸还原酶(MTRR)A66G位点基因多态性分布情况,分析其遗传风险分布地域性特征,为指导孕龄妇女个性化增补叶酸及出生缺陷一级预防提供依据。方法随机以湖北省恩施州建始县248位汉族女性为研究对象,检测其MTHFR C677T、A1298C及MTRR A66G基因位点多态性,采用统计学方法分析该地区基因的多态性分布特征,并与我国南北方具有代表性的若干地区进行比较。结果本地区的汉族女性MTHFR 677TT纯合突变基因型频率(14.1%),显著高于我国我们南方城市南宁、琼海和惠州(P0.05),显著低于北方城市乌鲁木齐、尚志、延边、银川、廊坊、烟台、济源、镇江和湘潭(P0.05);等位基因T频率为40.5%,与我国其他地区的比较,结论和C677T位点基因型的情况类似;MTHFR A1298C基因型分布情况与尚志、延边、廊坊、烟台、镇江、湘潭、南宁、惠州和琼海地区的人群差异有统计学意义;MTRR A66G位点的基因型频率和等位基因频率与其它地区比较均无统计学差异(P0.05)。结论建始县的汉族女性MTHFR基因多态性频度分布具有显著的地区特异性,MTRR基因多态性频度分布不具备显著的地区特异性。     

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。     

贵州苗、布依、侗、水四个少数民族Rh血型分布调查分析

目的了解贵州主要的4个少数民族中Rh血型分布及基因频率，为指导Rh溶血症防治提供科学依据。方法随机整群抽取贵州苗、布依、侗、水4个民族的无关个体进行Rh血型鉴定和分析。结果共筛查4个少数民族15992人，汉族对照4851人。发现Rh（D）阴性个体51名，苗族d基因频率0．0474、Rh阴性率为0．22％。布依族d基因频率0．0602、Rh阴性率为0．36％。侗族d基因频率0．0378、Rh阴性率为0．14％。水族d基因频率0．0307、Rh阴性率为0．09％。汉族（对照组）d基因频率0．0574、Rh阴性率为0．33％。4个少数民族均有表现型CCDee型最高（52．47％～59．66％）的共同特征。同时4个民族的基因型频率均以CDe最高，分别为苗族：0．7244、布依族：0．7389、侗族：0．7410、水族：0．7743。结论贵州4个少数民族苗、布依、侗、水族Rh血型分布特征，与国内南方少数民族相似。苗、侗、水族Rh阴性比例都低于汉族（0．33％），仅布依族Rh阴性率（0．36％）接近并略高于汉族。因此，贵州少数民族中Rh新生儿溶血症发生率不高。     

Genetic polymorphisms of methylenetetrahydrofolate reductase (MTHFR) and methionine synthase reductase (MTRR) in ethnic populations in Texas; a report of a novel MTHFR polymorphic site, G1793A.

The importance of hyperhomocysteinemia, birth defects, and vascular diseases has been the subject of intense investigations. The polymorphic MTHFR mutations (C677T and A1298C) cause mild hyperhomocysteinemia, especially in homozygotes for C677T, but also in compound heterozygotes for C677T/A1298C. The subject of this report is the frequency of the polymorphic mutations in the MTHFR gene C677T, C1298A, and newly discovered mutation G1793A, as well as the association with MTRR polymorphic site A66G in different ethnic groups. Four ethnic groups were studied: African-Americans, Caucasians, Hispanics, and Ashkenazi Jews. There are statistically significant differences in the frequency of these alleles in the different populations studied, which impacts compound heterozygosity for such alleles in these populations. DNA samples obtained from the blood of healthy individuals of African-Americans, Hispanics, and Caucasians from south Texas were analyzed and compared to those obtained from Ashkenazi Jewish individuals. The polymorphic site, the G1793A allele, is least frequent among Ashkenazi individuals, 1.3%, compared to 6.9% among Caucasians (P = 0.001), 5.8% among Hispanics (P = 0.012), and 3.1% among African-Americans. The MTRR polymorphic site shows the lowest allele frequency among Hispanics, 28.6%, compared to 34% among African-Americans, 43.1% among Ashkenazi Jews (P = 0.002), and 54.4% among Caucasians (P < 0.0001). Statistically significant differences in allele frequencies of C677T and C1298A polymorphisms were also observed in these populations. Compound heterozygosity for multiple polymorphic alleles may play a role in birth defects and vascular diseases.     

Methylenetetrahydrofolate Reductase (MTHFR) Allele Frequencies in Amerindians

Neural tube defects (NTDs) have been associated with abnormalities of folate metabolism. Methylenetetrahydrofolate reductase (MTHFR) is the regulatory enzyme for the conversion of homocysteine to methionine. The C677T mutation in the MTHFR gene affects folate distribution, and homozygosity for the T allele may be associated with an increased risk of NTDs. A second mutation, an A1298C transversion in this same gene, is also associated with an increased risk for NTDs but only in conjunction with the 677T allele. A low incidence of NTDs has been observed in high‐altitude populations; however, these studies did not provide information about the allele distribution of genes involved in folate metabolism. This investigation compares allele frequencies of the C677T and A1298C polymorphisms between Quechua people living at 3200–4200 m in the Peruvian Central Andes and an Aché group living at low altitude. Allele frequencies at both loci were not significantly different between the two populations. The absence of the 677T/677T genotypes and of the 677T/1298C arrangement in both groups may indicate a genetic contribution to reduced risk for NTDs; however, factors other than altitude are likely responsible for the low variant allele frequencies in these populations.     

MTHFR genetic polymorphism as a risk factor in Egyptian mothers with Down syndrome children

Recent reports linking Down syndrome (DS) to maternal polymorphisms at the methylenetetrahydrofolate reductase (MTHFR) gene locus have generated great interest among investigators in the field. The present study aimed at evaluation of MTHFR 677C/T and 1298A/C polymorphisms in the MTHFR gene as maternal risk factors for DS. Forty two mothers of proven DS outcomes and forty eight control mothers with normal offspring were included. Complete medical and nutritional histories for all mothers were taken with special emphasis on folate intake. Folic acid intake from food or vitamin supplements was significantly low (below the Recommended Daily Allowance) in the group of case mothers compared to control mothers. Frequencies of MTHFR 677T and MTHFR 1298C alleles were significantly higher among case mothers (32.1% and 57.1%, respectively) compared to control mothers (18.7% and 32.3%, respectively). Heterozygous and homozygous genotype frequencies of MTHFR at position 677 (CT and TT) were higher among case mothers than controls (40.5% versus 25% and 11.9% versus 6.2%, respectively) with an odds ratio of 2.34 (95% confidence interval [CI] 0.93-5.89) and 2.75 (95% CI 0.95-12.77), respectively. Interestingly, the homozygous genotype frequency (CC) at position 1298 was significantly higher in case mothers than in controls (33.3% versus 2.1% respectively) with an odds ratio of 31.5 (95% CI 3.51 to 282.33) indicating that this polymorphism may have more genetic impact than 677 polymorphism. Heterozygous genotype (AC) did not show significant difference between the two groups. We here report on the first pilot study of the possible genetic association between DS and MTHFR 1298A/C genotypes among Egyptians. Further extended studies are recommended to confirm the present work.     

Infants' MTHFR polymorphisms and nonsyndromic orofacial clefts susceptibility: A meta-analysis based on 17 case-control studies

Methylenetetrahydrofolate reductase (MTHFR), an important enzyme in folate metabolism, is thought to be involved in the development of nonsyndromic orofacial clefts (NSOC). However, conflicting results have been achieved when evaluating the associations between infants' MTHFR C677T and A1298C polymorphisms and the risk of NSOC. To obtain more precise estimations of these associations, a meta-analysis recruiting 17 case-control studies was performed. Among Asians we found that CT heterozygote, TT homozygote, and CT/TT of infants' MTHFR C677T variant could contribute to elevated risks of NSOC, compared with CC wild-type homozygote (OR?=?1.741, 95% CI?=?1.043-2.907 for CT vs. CC, OR?=?2.311, 95% CI?=?1.313-4.041 for TT vs. CC, and OR?=?1.740, 95% CI?=?1.051-2.882 for CT/TT vs. CC, respectively). Similar effect was also observed on MTHFR 677T T allele, when using C allele as a reference in Asians (OR?=?1.420, 95% CI?=?1.191-1.693, for T allele vs. C allele). Furthermore, in stratified analysis by types of disease, CT/CC was suggested to confer decreased susceptibility to CL/P under recessive genetic model (OR?=?0.854, 95% CI?=?0.730-1.000). For MTHFR A1298C, the MTHFR 1298C allele in the case group of Caucasians was significantly lower than that in the control group, suggesting a protective effect against NSOC in Caucasian populations (OR?=?0.711, 95% CI?=?0.641-0.790, for C allele vs. A allele). In conclusion, the meta-analysis provided confirmative evidences that infants' MTHFR C677T and A1298C polymorphisms were involved in the development of NSOC. ? 2012 Wiley Periodicals, Inc.     

Congenital heart defects and genetic variants in the methylenetetrahydroflate reductase gene

Background

Most non‐syndromic congenital heart defects (CHD) are caused by a complex interaction between maternal lifestyle factors, environmental exposures, and maternal and fetal genetic variants. Maternal periconceptional intake of folic acid containing vitamin supplements is reported to decrease the risk of CHD. The 677C→T and 1298A→C polymorphisms in the methylenetetrahydrofolate reductase (MTHFR) gene decrease enzyme activity.

Objective

To examine the relation between CHD and maternal and fetal MTHFR polymorphisms

Methods

375 nuclear families were studied. The transmission/disequilibrium test was used to test for transmission distortion in complete triads. A log‐linear approach was used to test for associations between CHD and maternal and offspring polymorphisms, and to estimate independently the contributions of maternal and fetal variants to relative risks. Haplotype frequencies were estimated and a haplotype transmission disequilibrium test carried out.

Results

The 1298C allele was transmitted less often than expected (p = 0.0013). There was no distortion in the transmission of the 677T allele, neither was there evidence of a parent of origin effect in the transmission of either of the single nucleotide polymorphisms. The 677C–1298C haplotype was also transmitted less often than expected (p = 0.0020). The relative risk associated with inheriting one copy of the 1298C allele was 0.64 (95% confidence interval, 0.48 to 0.87) and the that associated with inheriting two copies of the 1298C allele, 0.38 (0.21 to 0.70).

Conclusions

The apparent protective effect of the MTHFR 1298C allele against CHD could have several explanations and further study is needed.     

Genotypes of the C677T and A1298C polymorphisms of the MTHFR gene as a cause of human spontaneous embryo loss

BACKGROUND Polymorphisms C677T and A1298C of the MTHFR gene have been implicated in fetal viability. In this study, we determined the allele and genotype frequencies of these polymorphisms in different populations, including spontaneous abortion (SA) fetal tissues, with the objective of evaluating their impact on fetal viability. METHODS 342 samples of fetal tissues, selected from SA occurring during the 1980s, 230 samples from subjects born in the 1980s and a third set of samples from 204 subjects born in the 1950s, were genotyped by using TaqMan probes. RESULTS The wild CC genotype of the C677T polymorphism showed a strong protective effect against abortion (0.03 in SA versus 0.47 in 1950s and 0.43 in 1980s) (P < 0.0001). Genotypes of three mutations in the combinations of polymorphisms for C677T and A1298C showed a very low frequency in the living population; however, the three mutations genotypes were over expressed in the SA group (0.02 in 1950s; 0.03 in 1980s and 0.17 in SA) (P < 0.0001). Samples with four mutations (n = 2) were found only in the SA group. CONCLUSIONS There is no linkage disequilibrium between C667T and A1298C polymorphisms. Fetal viability is directly related to the CC genotype as a protector while the three and four mutation MTHFR genotypes appear to be a determinant on fetal non-viability and SA.     

贵州少数民族胱硫醚-β-合酶基因C699T的分布

目的 对中国贵州雷山苗族和三都水族群体胱硫醚-β-合酶基因C699T进行多态性分析,计算其基因频率,获取相应的遗传信息.方法 采用nest-PCR和变性梯度凝胶电泳(denaturing gradient gel electrophoresis,DGGE)技术寻找突变基因,对突变基因的PCR产物进行基因直接测序,并与文献报道的各种人群的相应数据进行比较.结果 雷山苗族和三都水族群体的胱硫醚-β-合酶基因699T等位基因频率分别为5.1%和5.4%.结论 雷山苗族和三都水族两个群体间胱硫醚-β-合酶基因699T等位基因差异无统计学意义,但它们均显著低于黑种人和白种人群体.