title: IFNG+874A/T polymorphisms and IFNG CA repeat polymorphism associated with asthma in Asian--a meta-analysis.
abstract: BACKGROUND
  Asthma is an etiologically complex disease and develops by the interaction of multiple genes and environmental factors. Previous studies suggested a linkage between the interferon-gamma (INFG) gene cluster in the chromosome 12q region and susceptibility to asthma.
  
  
  METHODS
  This meta-analysis was undertaken to examine the relationship between +874A/T and CA-repeat polymorphisms in INFG gene and asthma. Eligible articles were accumulated via online databases in October 2013. A total of nine articles were included that were associated with the +874A/T polymorphism, involving 470 cases and 574 controls, as well as articles involving CA-repeat polymorphisms, which included 365 cases and 517 controls. The meta-analysis was performed for heterogeneity and calculation of pooled odds ratio and evaluation of publication bias by Egger's linear regression test.
  
  
  RESULTS
  The differences between IFNG polymorphism and the susceptibility to asthma may vary across ethnicities and ages, and also that the allelic frequencies of the AA genotypes in IFNG at +874 is associated with an increased risk of asthma in the Chinese Han adult population; additionally, CA14 occurrence in the first intron can increase the risk of asthma in the Japanese population.
  
  
  CONCLUSIONS
  Our findings suggested that some polymorphisms in the IFNG gene could act as high prevalence-susceptibility markers of asthma. Larger scale studies are warranted to address these associations among different ethnic populations, ages and the severity of asthma prognosis.
authors.affiliation: Laboratory for Environment and Health, School of Earth and Environment, Anhui University of Science and Technology, Huainan , Anhui , China .
authors.forename: Yuee
authors.initials: Y
authors.lastname: Huang
authors.forename: Yongjun
authors.initials: Y
authors.lastname: Zhang
authors.forename: Wenjie
authors.initials: W
authors.lastname: Sun
authors.forename: Kayllyn
authors.initials: K
authors.lastname: Germ
authors.forename: Yuxin
authors.initials: Y
authors.lastname: Jiang
authors.forename: Wei
authors.initials: W
authors.lastname: Guo
authors.forename: Chao
authors.initials: C
authors.lastname: Xu
authors.forename: Chaopin
authors.initials: C
authors.lastname: Li
mesh_terms: D044466:Asian People / Q000235:genetics*; D001249:Asthma / Q000235:genetics*; D020022:Genetic Predisposition to Disease; D014644:Genetic Variation; D005838:Genotype; D006801:Humans; D007371:Interferon-gamma / Q000235:genetics*; D020641:Polymorphism, Single Nucleotide
chemical_list: D007371:Interferon-gamma
keywords: Asthma; IFNG CA repeat; IFNG+874A/T; polymorphism