Folate metabolism gene polymorphisms MTHFR C677T and A1298C and risk for preeclampsia: a meta-analysis

Objectives

MTHFR C677T and A1298C have been associated with the risk of preeclampsia (PE), but with conflicting results. We performed this meta-analysis to derive a more precise estimation of the association between MTHFR polymorphisms and PE.

Study design

An electronic search of PubMed and Chinese Biomedicine database was conducted to select studies for meta-analysis. 54 case controlled studies containing MTHFR C677T and A1298C gene polymorphisms were chosen, and odds ratio (OR) with confidence interval (CI) was used to assess the strength of this association.

Result

These studies evaluated 7398 cases and 11230 controls for MTHFR C677T. The overall results suggested that MTHFR C677T was associated with the risk of PE. (T vs. C: OR = 1.157, 95 % CI: 1.057-1.266, p=0.002; TT+CT vs. CC: OR=1.165, 95 % CI : 1.049-1.293, P = 0.004; TT vs. CT + CC: OR = 1.371, 95 % CI: 1.153-1.63, p < 0.001). We also evaluated 1103 cases and 988 controls for MTHFR A1298C but could not demonstrate an increased risk of PE for this polymorphism (p=0.667). A symmetric funnel plot, the Egger’s test (p = 0.819) suggested a lack of publication bias.

Conclusion

This meta-analysis supports the idea that MTHFR C677T genotype is associated with increased risk for PE, especially in the case of Asians and Caucasians.     

Folate metabolism gene polymorphisms MTHFR C677T and A1298C and risk for Down syndrome offspring: a meta-analysis

Objectives

MTHFR C677T and A1298C have been associated with the risk of having an infant with Down syndrome (DS), but results were conflicting. We performed this meta-analysis to derive a more precise estimation of the association between maternal MTHFR polymorphisms and DS.

Study design

An electronic search of PubMed and Chinese Biomedicine database was conducted to select studies for meta-analysis. Twenty-eight case–control studies containing MTHFR C677T and A1298C gene polymorphisms were chosen, and odds ratio (OR) with confidence interval (CI) was used to assess the strength of this association.

Results

Case–control studies including 2806 cases and 4597controls for MTHFR C677T were identified. The overall results suggested that the variant genotypes MTHFR C677T were associated with DS risk (TT+CT vs. CC: OR = 1.305, 95% CI: 0.125–1.514, p = 0). In the stratified analysis, individuals with the T-carriers genotype in the dominant model had increased risk of DS (OR = 1.171, 95% CI: 0.976–1.405, p = 0.09) in Caucasian subjects and in Asian subjects (OR = 1.749, 95% CI: 1.084–2.824, p = 0.022). In addition, case–control studies including 1854 cases and 2364 controls for MTHFR A1298C were chosen. Associations between MTHFR A1298C and the risk of having a child with DS were not found. A symmetric funnel plot, the Egger's test (p = 0.126) suggested a lack of publication bias.

Conclusion

This meta-analysis supports the idea that MTHFR C677T genotype is associated with increased risk for DS offspring.     

MTHFR C677T polymorphism and recurrent early pregnancy loss risk in north Indian population

Recurrent early pregnancy loss (REPL) is a multifactorial disorder as both genetic and environmental factors contribute to the development of disease. Folate metabolism is an important mechanism to ensure proper fetal growth. Hyperhomocysteinemia leads to a number of disorders and REPL is one of them. In a case-control study DNA from 106 cases with the history of 3 or more REPL and 140 healthy fertile controls with successful pregnancy outcomes were genotyped for C677T single-nucleotide polymorphism (SNP) of the MTHFR (methylenetetrahydrofolate reductase) gene through polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP), which was further confirmed by sequencing. Allele frequencies of REPL cases were compared with healthy controls and a statistically significant association was found between REPL and the mutant T allele (χ2 = 8.786, odds ratio [OR] = 2.20, 95% confidence interval [CI] = 1.323-3.9658, P = .003). The genotype frequencies of SNP C677T also differ significantly between these 2 groups (χ2 = 8.237, P = .016). The OR for heterozygous CT in the REPL versus controls is 1.9591 (95% CI = 1.0285-3.7318, P = .04). The OR for TT homozygous is 6.3009 (95% CI = 1.2065, P = .02). Combined odds ratio of CT and TT against the control has been calculated as 2.2194 (95% CI = 1.2029-4.0952, P = .02) which is also significant. Thus the present study clearly indicates that homozygosity and heterozygosity for the MTHFR C677T polymorphism confer a 6.3009- and 1.9591-fold increased risk of idiopathic REPL, respectively.     

677 C-->T polymorphism of the methylenetetrahydrofolate reductase gene and preeclampsia

OBJECTIVE: To evaluate C to T substitution at nucleotide 677 of N(5), N(10)-methylenetetrahydrofolate reductase gene in women with prior preeclamptic or normotensive pregnancies. METHODS: Methylenetetrahydrofolate reductase genotypes were determined in 113 Finnish women with preeclamptic first pregnancies and 103 controls with one or more normotensive pregnancies, using polymerase chain reaction and restriction enzyme analysis. Preeclampsia was defined as severe in 100 women who fulfilled one or more of the subsequent criteria: systolic blood pressure (BP) at least 160 mmHg, diastolic BP at least 110 mmHg, or proteinuria at least 2 g per 24-hour urine collection. RESULTS: There were no significant differences in prevalences of the methylenetetrahydrofolate reductase genotypes (CC, CT, and TT) between groups (57%, 40%, and 3% in the preeclamptic group and 54%, 39%, and 7%, respectively, in controls). The frequency of the T677 allele was 0.23 in the preeclamptic group and 0.26 in the control group (difference 0.03; 95% confidence interval -0.08, 0.14; P =.51). Our sample had 60% power to detect a difference of the allele frequencies similar to that (0.12) reported previously. The result was similar when analysis was restricted to patients with severe preeclampsia (T677 allele frequency 0.22). CONCLUSION: A carrier status for the T677 allele of the methylenetetrahydrofolate reductase gene does not predispose to preeclampsia, at least in the Finnish population.     

Combined heterozygosity for methylenetetrahydrofolate reductase (MTHFR) mutations C677T and A1298C is associated with abruptio placentae but not with intrauterine growth restriction.

OBJECTIVE: This study was undertaken to investigate the involvement of MTHFR gene mutations C677T and A1298C implicated in vascular disease, in patients with abruptio placentae and intrauterine growth restriction (IUGR). STUDY DESIGN: DNA was extracted from blood samples of 54 patients with placental vasculopathy (18 patients with abruptio placentae and 36 with IUGR) and 114 control patients and amplified by the polymerase chain reaction (PCR). The resulting fragments were subjected to restriction enzyme analysis and resolved by gel electrophoresis. RESULTS: A significant association could be demonstrated between mutation A1298C and both abruptio placentae and IUGR. Combined heterozygosity for mutations C677T and A1298C was detected in 22.2% of abruptio placentae cases. CONCLUSIONS: Combined heterozygosity for MTHFR mutations C677T and A1298C may represent a genetic marker for abruptio placentae.     

Association of COMT G675A and MTHFR C677T polymorphisms with hypertensive disorders of pregnancy in Mexican mestizo population

ObjectiveTo investigate the relationship between COMT G675A and MTHFR C677T polymorphisms and hypertension disorders of pregnancy (HDP) in a Mexican mestizo population.Design and methodsThis case-control study involved 194 HDP and 194 normoevolutive pregnant women. The polymorphisms were genotyped by real time PCR.ResultsOur results showed that the COMT AA genotype increases the risk to HDP (OR: 2.67; 95% CI 1.33–5.35), preeclampsia (OR: 2.69; 95% CI 1.00–7.22) and gestational hypertension (OR: 3.87; 95% CI 1.25–12.0). Furthermore, the double mutant genotype (COMTAA/MTHFRTT) potency the risk to HDP more than two times (OR: 5.21; 95% CI 1.12–24.3, p = 0.019).ConclusionOur work provides evidence that COMT 675AA genotype is a risk factor for HDP and that this risk is increased by the presence of MTHFR 677TT genotype in a Mexican mestizo population.     

Prothrombin 20210 G-->A, MTHFR C677T mutations in women with venous thromboembolism associated with pregnancy

Over 50 unselected women with maternal venous thromboembolism were screened for the prothrombin 20210 G→A and MTHFR C677T mutations, in addition to screening for other thrombophilias. The prevalence of thrombophilia in these women was compared with its prevalence in the general population in our area. The prothrombin (OR 4.4; 95% CI 1.2-16) and factor V Leiden (OR 4.5; 95% CI 2.1-14.5) mutations were more common in our patients, compared with the general population, whereas women homozygous for the C677T mutation in the methylene tetrahydrofolate reductase gene (OR 0.45; 95% CI 0.13-1.58) were not. It is recommended that women with a personal or strong family history of venous thromboembolism should be screened for the prothrombin mutation either before or early in pregnancy, in addition to screening for other thrombophilias. Screening for the MTHFR mutation does not appear to identify women at increased risk of maternal venous thrombosis.     

MTHFR C677T polymorphism was an ethnicity-dependent risk factor for cervical cancer development: evidence based on a meta-analysis

Introduction

Many studies have studied the associations between 5, 10-methylene tetrahydrofolate reductase (MTHFR) polymorphisms and susceptibilities of cervical cancer and cervical intraepithelial neoplasia (CIN); however, the results were inconsistent. The aim of this study was to further assess the relationships by the method of meta-analysis.

Materials and methods

Two investigators independently searched the PubMed, Embase, Wang Fang (Chinese database) and CNKI (China National Knowledge Infrastructure), with latest update to July 1st, 2011. The pooled odds ratio (OR) and 95 % confidence interval (95 % CI) were used to assess the strength of the associations by using fixed- or random-effect model.

Results

Ten case–control studies were included in this meta-analysis including a total of 1,803 cervical cancer or CIN cases and 2,363 controls. Pooled analyses showed that T allele of MTHFR C677T was significantly associated with increased CIN risk [OR (95 % CI): 1.28 (1.03–1.50) for CT vs. CC], especially for low-grade CIN risk. In addition, MTHFR C677T rather than A1298C polymorphism was associated with risk of cervical cancer. Stratifying analyses for ethnicity indicated that T allele of MTHFR C677T was associated with increased cervical cancer risk for Asian [OR (95 % CI): 1.56 (1.17–2.08) for TT vs. CC; 1.53 (1.19–1.96) for TT vs. C carriers] while decreased risk for Caucasian [OR (95 % CI): 0.63 (0.45–0.89) for TT vs. CC; 0.66 (0.56–0.79) for T carriers vs. CC].

Conclusion

This meta-analysis suggested that there was no association between MTHFR A1298C polymorphism and cervical cancer risk. However, MTHFR C677T was an ethnicity-dependent risk factor for cervical cancer occurrence. In addition, T allele of C677T was significantly associated with risk of low grade of CIN incidence. Because of modest limitations of our study, well-designed studies with large sample size were needed to confirm our findings in the future.     

原因不明复发性流产患者血中亚甲基四氢叶酸还原酶基因C677T和A1298C位点突变的研究

目的　探讨 5 ,10 亚甲基四氢叶酸还原酶基因C6 77T和A12 98C位点突变与原因不明复发性流产 (unexplainedrecurrentspontaneousabortion ,URSA)易感因素的相关性。 方法　采用PCR-限制性片段长度多态性方法 ,检测 14 7例原因不明复发性流产患者 (URSA组 )和 82例有正常妊娠史的妇女 (对照组 )血中亚甲基四氢叶酸还原酶基因C6 77T和A12 98C位点突变。结果　 ( 1)C6 77T的 3种基因型在URSA组和对照组总体分布存在显著性差异 (P =0 0 12 ) ,其中URSA组 :基因型CC占 33 3% ,CT占 5 3 1% ,TT占 13 6 % ,对照组 :基因型CC占 5 2 4 % ,CT占 5 1 5 % ,TT占 6 1%。两组 6 77CC基因表达差异有显著性 (P =0 0 0 5 ) ,URSA组C和T等位基因分别为 4 0 1%、5 9 9% ,两组基因分布情况比较 ,差异有显著性 (P <0 0 0 5 ) ;( 2 )A12 98C的 3种基因型在URSA组和对照组中总体分布情况比较 ,差异无显著性 ,12 98AA/AC/CC基因型和A/C等位基因频率比较 ,差异无显著性 (P >0 0 0 5 ) ;( 3)C6 77T/A12 98C连锁基因分析显示 ,8种连锁基因型中 ,URSA组 6 77CC/ 12 98AA表达频率显著降低 ,而 6 77(CT TT) / 12 98CC仅在URSA组中表达。结论　URSA与亚甲基四氢叶酸还原酶基因C6 77T和A12 98C位点突变有关。     

Polymorphisms of the methylenetetrahydrofolate reductase gene (C677T and A1298C) in nulliparous women complicated with preeclampsia

Objective: To determine the prevalence of C677T and A1298C Single-nucleotide polymorphisms (SNPs) of the MTHFR gene in nulliparous women complicated with preeclampsia (PE).

Methods: One hundred fifty gestations complicated with PE and their corresponding controls without the disease were recruited for the genotyping of C677T and A1298C polymorphisms of the MTHFR gene using restriction fragment length polymorphism polymerase chain reaction. Secondarily, homocysteine (HCy) plasma levels were measured in preeclamptic women displaying the CC genotype of the A1298C polymorphism (homozygous) and compared to HCy levels determined among controls with the normal AA genotype for the A1298C variant.

Results: Only the mutant CC genotype of the A1298C polymorphism was associated to higher risk of presenting PE, as frequency of this genotype was significantly higher among cases than controls (15.3% versus 0.7%, p?p?=?0.0001). Women with the mutant CC A1298C SNP displayed higher plasma HCy levels as compared to controls with normal AA A1298C genotype (8.4?±?2.6 versus 7.5?±?2.7?mmoL/L p?=?0.04).

Conclusion: Prevalence of the CC mutant genotype of the A1298C polymorphism was higher among PE women. This mutation among PE women was related to increased neck circumference and higher HCy levels. Future research should aim at linking these gestational findings with obesity and cardiovascular risk.     

The effect of parental 5,10-methylenetetrahydrofolate reductase 677C/T and 1298A/C gene polymorphisms on response to single-dose methotrexate in tubal ectopic pregnancy

Object: The aim of this study was to assess the effect of parental 5,10-methylenetetrahydrofolate reductase (MTHFR) gene polymorphisms (677C/T and 1298A/C) on response to single-dose methotrexate (MTX) treatment in tubal ectopic pregnancy (TEP).

Materials and methods: In this prospective cohort study, cases with unruptured TEPs were grouped into two according to their response to single-dose MTX treatment (Group 1: responsive, n:88; Group 2: unresponsive, n:21). The groups were compared with regard to baseline demographic and clinical parameters. As a main outcome measure, the independent effects of parental MTHFR gene polymorphisms on response to single dose MTX treatment were evaluated.

Results: One hundred and nine unruptured TEP were included in the final analysis. The mean maternal age was 29.30?±?5.21 years, gravity 2 (min–max: 1–5), parity 1 (min–max: 0–4). The median serum beta-human chorionic gonadotropin (β-hCG) was 1403.35?MI/I (Q₁–Q₃: 517–2564). The overall response rate was 81% (88/109). The groups were similar with respect to basic baseline demographic data and serum β-hCG level. Binary logistic regression analysis showed that the presence of parental MTHFR677C/T and 1298A/C polymorphism were not independent factor predicting treatment success (p?>?0.05). The only independent factor for resistance to single dose MTX was the previous TEP (OR: 4.47 (1.18–16.9)).

Conclusion: Parental MTHFR 677C/T and 1298A/C mutations do not predict the outcome of single dose intramuscular MTX treatment in unruptured TEP.     

ACL(+)复发性流产与亚甲基四氢叶酸还原酶C677T和A1298C位点突变关联的研究

目的:探讨亚甲基四氢叶酸还原酶基因(methylenetetrahydrofolate reductase,MTHFR)C677T和A1298C位点突变与抗心磷脂抗体(anticard iolipin antibody,ACL)阳性复发性流产是否相关。方法:采用聚合酶链式反应-限制性片断长度多态性方法,检测39例原因不明复发性流产和82例正常对照的亚甲基四氢叶酸还原酶基因C677T和A1298C位点突变。结果:MTHFR 677 3种基因型(CC、CT和TT)在ACL(+)流产组和对照组分布有统计学差异(P=0.045),进一步分析表明,677TT在患者组中表达频率显著增大(P=0.026),T等位基因频率在患者组中也显著增大(P=0.018),MTHFR1298相关3种基因型(AA、AC和CC)和A、C等位基因频率在2组中分布无差异,同时发现8种C677T/A1298C连锁基因型,但都与ACL(+)复发性流产无关。结论:ACL(+)复发性流产与MTHFR C677T突变有关,表明除自身抗体有关的获得性凝血途径以外,遗传性凝血因素在此种类型的流产发生中也起一定的作用。     

亚甲基四氢叶酸还原酶基因677位多态性、高同型半胱氨酸血症与复发性流产

目的:探讨亚甲基四氢叶酸还原酶基因(MTHFR)多态性(C677T)与高同型半胱氨酸(Hcy)血症以及复发性流产之间的关系。方法:采用前瞻性病例对照研究方法,收集71例复发性自然流产患者为病例组,另征集同期58例有正常妊娠史者为对照组,利用PCR-RFLP方法研究MTHFR基因多态性(C677T);同时应用酶法测定血清同型半胱氨酸水平;并随访病例组的妊娠结局。结果:①MTHFR基因677位点的3种基因型在病例组和对照组分布分别为CC:14.1%vs 43.1%、CT:49.3%vs 25.9%、TT:36.6%vs 31.0%,组间比较有极显著统计学差异(χ2=14.7,df=2,P=0.001);其中CC基因型在病例组显著降低(P=0.000,OR=0.216,95%CI:0.093-0.505);T等位基因分布在病例组显著升高(61.3%vs 38.7%,P=0.006)。②129例研究对象中TT基因型血同型半胱氨酸水平显著升高(P=0.000):TT为19.0±9.5 nmol/L、CC为13.1±6.2 nmol/L、CT为11.7±4.0 nmol/L,病例组和对照组高Hcy水平组间无统计学差异(P>0.05)。③病例组中有38.0%(27/71)为高Hcy血症,叶酸治疗有效。结论:MTHFR基因多态性(C677T)与复发性流产有关;MTHFR基因TT型与高Hcy血症有关;叶酸可用于治疗高Hcy血症且有助于改善下次妊娠结局。     

Polymorphisms of the methylenetetrahydrofolate reductase gene (C677T and A1298C) in the placenta of pregnancies complicated with preeclampsia

Abstract

Background: Preeclampsia has been related to single-nucleotide polymorphisms (SNPs) of the methylenetetrahydrofolate reductase (MTHFR) gene; however, data regarding the placenta are still lacking.

Objective: To determine the frequency of C677T and A1298C SNPs of the MTHFR gene in the placenta of preeclamptic pregnancies and healthy controls.

Methods: Genotyping of C677T and A1298C polymorphisms of the MTHFR gene using RFLP-PCR was performed to the placenta of 100 gestations (n?=?50 complicated with preeclampsia and n?=?50 normal controls matched for parity and maternal age).

Results: Gestational age at birth and neonatal and placental weight were significantly lower in women with preeclampsia as compared to controls. The TT genotype of the C677T polymorphism was threefold more prevalent in preeclamptic placentas as compared to the placenta of controls (24.0% versus 8.0%, p?=?0.001). Upon pooled analysis (n?=?100), placental and neonatal weights were significantly lower in placentas displaying this genotype (TT, C677T) as compared with the CC genotype.

Conclusion: This study found that the frequency of the TT mutant genotype of the C677T polymorphism was higher in the placenta of pregnancies complicated with preeclampsia. There is a need for further research in this matter.