title: Polymorphisms in the transforming growth factor-beta1 gene and the risk of asthma: A meta-analysis.
abstract: OBJECTIVE
  Polymorphisms in the transforming growth factor-beta1 (TGF-beta1) gene have been implicated in susceptibility to asthma, but a large number of studies have reported inconclusive results. A meta-analysis was performed to investigate the association between polymorphisms in the TGF-beta1 gene and asthma susceptibility.
  
  
  METHODS
  Searches were performed of Medline (Ovid), PubMed, the Chinese Biological Medicine Database (CBM), the Chinese Journals Full-text Database (CNKI), the Cochrane Library Database and the Web of Science, covering all papers published up to 30 April 2009. Statistical analysis was performed using Revman4.2.8 and STATA10.0 software.
  
  
  RESULTS
  Two polymorphisms (-509C/T and 915G/C(G25C)) were investigated in 14 studies, involving 2979 asthma patients and 4941 control subjects. The results showed that individuals carrying the -509T allele (TT+TC) had a 36% increased risk of asthma, when compared with homozygotes (-509CC) (OR 1.36, 95% CI: 1.12-1.65). However, there was no significant association with risk of asthma in carriers of the 915C allele (GC+CC) compared with 915GG homozygotes (OR 1.05, 95% CI: 0.65-1.70). In a subgroup analysis by ethnicity, the risk of asthma associated with the -509T allele was significantly elevated among Asians (OR 1.50, 95% CI: 1.04-2.17) but not Caucasians (OR 1.16, 95% CI: 1.00-1.36). In a subgroup analysis by age, the -509T allele was associated with a significantly elevated risk of asthma among adults (OR 1.45, 95% CI: 1.09-1.92) but not children (OR 1.19, 95% CI: 0.96-1.46).
  
  
  CONCLUSIONS
  This meta-analysis suggested that the -509C/T polymorphism in the TGF-beta1 gene may be a risk factor for asthma. To further evaluate gene-gene and gene-environment interactions between polymorphisms in the TGF-beta1 gene and asthma susceptibility, more studies involving thousands of patients are required.
authors.affiliation: Department of Respiratory Medicine, West China Hospital of Sichuan University, Chengdu, Sichuan, China.
authors.forename: Yonggang
authors.initials: Y
authors.lastname: Zhang
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.forename: Jin
authors.initials: J
authors.lastname: Huang
authors.forename: Xiaobo
authors.initials: X
authors.lastname: Li
authors.forename: Chao
authors.initials: C
authors.lastname: He
authors.forename: Can
authors.initials: C
authors.lastname: Tian
authors.forename: Chunhong
authors.initials: C
authors.lastname: Peng
authors.forename: Liang
authors.initials: L
authors.lastname: Guo
authors.forename: Yuling
authors.initials: Y
authors.lastname: Xiao
authors.forename: Hong
authors.initials: H
authors.lastname: Fan
mesh_terms: D000328:Adult; D044466:Asian People / Q000235:genetics; D001249:Asthma / Q000235:genetics*; D002648:Child; D020022:Genetic Predisposition to Disease; D006801:Humans; D011110:Polymorphism, Genetic; D012307:Risk Factors; D053773:Transforming Growth Factor beta1 / Q000235:genetics*; D044465:White People
chemical_list: D053773:Transforming Growth Factor beta1