title: Association between interleukin-18 gene polymorphism 105A/C and asthma.
abstract: BACKGROUND
  IL-18 has been shown to exert anti-allergic or allergy-promoting activities, but the existence of genetic polymorphisms in the coding regions of IL-18 gene has not been demonstrated.
  
  
  OBJECTIVE
  The aim of this study was to investigate whether polymorphism is present in the coding regions of the IL-18 gene and, if so, to further analyse the association between polymorphism and asthma in a case-control study.
  
  
  METHODS
  We screened the coding regions of the IL-18 gene for polymorphisms by using PCRsingle-stranded conformation polymorphism and direct sequencing of PCR products, followed by analysis of the association between polymorphism and asthma.
  
  
  RESULTS
  We identified one polymorphism (105A/C) in the coding regions. The frequency of the 105A allele was significantly higher in asthmatic patients than in controls (P<0.01; odds ratio (OR)=1.83 (1.37-2.26)). Significant linkage disequilibrium was observed between the 105A/C and -137G/C polymorphisms in the 5' flanking region of the IL-18 gene (D=0.58, P<0.0001). However, in asthmatic patients the 105A allele was not associated with either total serum IgE or IL-18 levels.
  
  
  CONCLUSIONS
  The 105A/C polymorphism of the IL-18 gene may be associated with the pathogenesis of asthma.
authors.affiliation: Department III of Internal Medicine, Osaka University Medical School, Osaka Department of Pediatrics, Fukui Medical University School of Medicine, Fukui, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Higa
authors.forename: T
authors.initials: T
authors.lastname: Hirano
authors.forename: M
authors.initials: M
authors.lastname: Mayumi
authors.forename: M
authors.initials: M
authors.lastname: Hiraoka
authors.forename: Y
authors.initials: Y
authors.lastname: Ohshima
authors.forename: M
authors.initials: M
authors.lastname: Nambu
authors.forename: E
authors.initials: E
authors.lastname: Yamaguchi
authors.forename: N
authors.initials: N
authors.lastname: Hizawa
authors.forename: N
authors.initials: N
authors.lastname: Kondo
authors.forename: E
authors.initials: E
authors.lastname: Matsui
authors.forename: Y
authors.initials: Y
authors.lastname: Katada
authors.forename: A
authors.initials: A
authors.lastname: Miyatake
authors.forename: I
authors.initials: I
authors.lastname: Kawase
authors.forename: T
authors.initials: T
authors.lastname: Tanaka
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001249:Asthma / Q000235:genetics* / Q000276:immunology; D016022:Case-Control Studies; D002648:Child; D002675:Child, Preschool; D005787:Gene Frequency; D020022:Genetic Predisposition to Disease; D005838:Genotype; D006801:Humans; D007073:Immunoglobulin E / Q000097:blood; D007223:Infant; D020382:Interleukin-18 / Q000097:blood / Q000235:genetics*; D015810:Linkage Disequilibrium / Q000276:immunology; D008875:Middle Aged; D011110:Polymorphism, Genetic; D018807:Polymorphism, Single-Stranded Conformational; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D020382:Interleukin-18; D007073:Immunoglobulin E