title: Polymorphisms of -174G>C and -572G>C in the interleukin 6 (IL-6) gene and coronary heart disease risk: a meta-analysis of 27 research studies.
abstract: OBJECTIVE
  Elevated serum IL-6 level is a risk factor for coronary heart disease (CHD). The -174 G>C and -572 G>C polymorphisms in the IL-6 gene have previously been shown to modulate IL-6 levels. But the association between the -174 G>C and -572 G>C polymorphisms and the risk of CHD is still unclear. A meta-analysis of all eligible studies was carried out to clarify the role of IL-6 gene polymorphisms in CHD.
  
  
  RESULTS
  PubMed, EMBASE, Vip, CNKI and CBM-disc were searched for eligible articles in English and Chinese that were published before October 2010. 27 studies involving 11580 patients with CHD and 17103 controls were included. A meta-analysis was performed for the included articles using the RevMan 5.0 and Stata 10.0 softwares. Overall, the -174 C allele was not significantly associated with CHD risk (ORs = 1.04, 95%CI = 0.98 to 1.10) when compared with the -174 G allele in the additive model, and meta-analysis under other genetic models (dominant, recessive, CC versus GG, and GC versus GG) also did not reveal any significant association. On the contrary, the -572 C allele was associated with a decreased risk of CHD when compared with the -572 G allele (ORs = 0.79, 95%CI = 0.68 to 0.93). Furthermore, analyses under the recessive model (ORs = 0.69, 95% = 0.59 to 0.80) and the allele contrast model (genotype of CC versus GG, ORs = 0.49, 95% = 0.35 to 0.70) yielded similar results. However, statistical significance was not found when the meta-analysis was restricted to studies focusing on European populations, studies with large sample size, and cohort studies by using subgroup analysis.
  
  
  CONCLUSIONS
  The -174 G>C polymorphism in the IL-6 gene is not significantly associated with increased risks of CHD. However, The -572 G>C polymorphism may contribute to CHD development. Future investigations with better study design and large number of subjects are needed.
authors.affiliation: The Centre of Evidence Based Medicine, Academy of Integrative Medicine, Fujian University of Traditional Chinese Medicine, Shangjie University Town, Fuzhou, China. zhgh_1969@yahoo.com.cn
authors.forename: Guo-hua
authors.initials: GH
authors.lastname: Zheng
authors.forename: Hai-ying
authors.initials: HY
authors.lastname: Chen
authors.forename: Shang-Quan
authors.initials: SQ
authors.lastname: Xiong
mesh_terms: D003327:Coronary Disease / Q000453:epidemiology / Q000235:genetics*; D030541:Databases, Genetic; D005787:Gene Frequency; D056726:Genetic Association Studies; D006801:Humans; D015850:Interleukin-6 / Q000097:blood / Q000235:genetics*; D009154:Mutation; D011110:Polymorphism, Genetic; D039781:PubMed; D012306:Risk
chemical_list: D015850:Interleukin-6