title: Associations of MTHFR gene polymorphisms with hypertension and hypertension in pregnancy: a meta-analysis from 114 studies with 15411 cases and 21970 controls.
abstract: BACKGROUND
  Several epidemiological studies have investigated the associations of methylenetetrahydrofolate reductase (MTHFR) C677T and A1298C polymorphisms with hypertension (H) or hypertension in pregnancy (HIP). However, the results were controversial. We therefore performed a comprehensive meta-analysis to provide empirical evidences on the associations.
  
  
  METHODS
  The English and Chinese databases were systematically searched to identify relevant studies. Odds ratios (ORs) and 95% confidence intervals (CIs) were calculated to evaluate the strength of the associations. Meta-regression, subgroup analysis, sensitivity analysis, cumulative meta-analysis and assessment of publication bias were performed in our study.
  
  
  RESULTS
  A total of 114 studies with 15411 cases and 21970 controls were included, 111 studies with 15094 cases and 21633 controls for the C677T polymorphism and 21 with 2533 cases and 2976 controls for the A1298C polymorphism. Overall, the C677T polymorphism was significantly associated with H and HIP (H & HIP: OR = 1.26, 95% CI = 1.17-1.34; H: OR = 1.36, 95% CI = 1.20-1.53; HIP: OR = 1.21, 95% CI = 1.08-1.32). Stratified analysis by ethnicity revealed a significant association among East Asians and Caucasians, but not among Latinos, Black Africans, and Indians and Sri Lankans. In the stratified analyses according to source of controls, genotyping method, sample size and study quality, significant associations were observed in all the subgroups, with the exception of population based subgroup in H studies and large sample size and "others" genotyping method subgroups in HIP studies. For the A1298C polymorphism, no significant association was observed either in overall or subgroup analysis under all genetic models.
  
  
  CONCLUSIONS
  This meta-analysis suggests that the MTHFR C677T rather than A1298C polymorphism may be associated with H & HIP, especially among East Asians and Caucasians.
authors: Environment and Non-Communicable Diseases Research Center, School of Public Health, China Medical University, Shenyang, China.
authors: Boyi
authors: B
authors: Yang
authors: Environment and Non-Communicable Diseases Research Center, School of Public Health, China Medical University, Shenyang, China.
authors: Shujun
authors: S
authors: Fan
authors: Environment and Non-Communicable Diseases Research Center, School of Public Health, China Medical University, Shenyang, China.
authors: Xueyuan
authors: X
authors: Zhi
authors: Environment and Non-Communicable Diseases Research Center, School of Public Health, China Medical University, Shenyang, China.
authors: Yongfang
authors: Y
authors: Li
authors: Environment and Non-Communicable Diseases Research Center, School of Public Health, China Medical University, Shenyang, China.
authors: Yuyan
authors: Y
authors: Liu
authors: Environment and Non-Communicable Diseases Research Center, School of Public Health, China Medical University, Shenyang, China.
authors: Da
authors: D
authors: Wang
authors: Environment and Non-Communicable Diseases Research Center, School of Public Health, China Medical University, Shenyang, China.
authors: Miao
authors: M
authors: He
authors: Department of Medical and Molecular Genetics, School of Medicine, Indiana University, Indianapolis, Indiana, United States of America.
authors: Yongyong
authors: Y
authors: Hou
authors: Environment and Non-Communicable Diseases Research Center, School of Public Health, China Medical University, Shenyang, China.
authors: Quanmei
authors: Q
authors: Zheng
authors: Environment and Non-Communicable Diseases Research Center, School of Public Health, China Medical University, Shenyang, China.
authors: Guifan
authors: G
authors: Sun
mesh_terms: D044466:Asian People / Q000235:genetics; D005260:Female; D006801:Humans; D046110:Hypertension, Pregnancy-Induced / Q000208:ethnology / Q000235:genetics*; D042965:Methylenetetrahydrofolate Reductase (NADPH2) / Q000235:genetics*; D011110:Polymorphism, Genetic; D011247:Pregnancy; D044465:White People / Q000235:genetics
chemical_list: C573423:MTHFR protein, human; D042965:Methylenetetrahydrofolate Reductase (NADPH2)