title: Polymorphisms of the IL12B, IL1B, and TNFA genes and susceptibility to asthma.
abstract: BACKGROUND
  Asthma is one of the most common chronic inflammatory diseases in developed countries. Susceptibility to asthma is associated with interaction between multiple genes and environmental factors. Several cytokines play a major role in the pathophysiology of the disease.
  
  
  OBJECTIVE
  We analyzed the distribution of cytokine gene polymorphisms in a group of patients with asthma and a control group in order to determine the effect of these variants, or their combinations, on the development of clinical phenotypes.
  
  
  METHODS
  We genotyped 22 single-nucleotide polymorphisms (SNPs) corresponding to 13 cytokine genes (IFNG, IL1A, IL1B, IL1R1, IL1RN, IL2, IL4, IL4R, IL6, IL10, IL12B, TGFB1, and TNFA) in 376 individuals (219 asthmatic patients and 157 controls). Genetic association was evaluated using genotype and allele models for different asthma phenotypes. Gene-gene interactions were explored using multifactor dimensionality reduction.
  
  
  RESULTS
  Genotype AC of IL12B-1188 was associated with the presence of asthma. A significant association was detected between 2 SNPs analyzed in TNFA (-308 and -238) and atopic asthma and severe-persistent asthma. The IL1B TT haplotype (3962T and -511T) was also associated with atopy and moderate-persistent asthma.
  
  
  CONCLUSIONS
  Our data show that the presence of SNPs in IL12B, TNFA, and IL1B was significantly associated with asthma, atopy, and severity of asthma.We also highlight the importance of genetic context, haplotype, and gene-gene interaction analysis in genetic association studies.
authors.forename: J
authors.initials: J
authors.lastname: Padrón-Morales
authors.forename: C
authors.initials: C
authors.lastname: Sanz
authors.forename: I
authors.initials: I
authors.lastname: Dávila
authors.forename: F
authors.initials: F
authors.lastname: Muñoz-Bellido
authors.forename: F
authors.initials: F
authors.lastname: Lorente
authors.forename: M
authors.initials: M
authors.lastname: Isidoro-García
mesh_terms: D000328:Adult; D000368:Aged; D001249:Asthma / Q000209:etiology / Q000235:genetics*; D016022:Case-Control Studies; D004843:Epistasis, Genetic; D005260:Female; D020022:Genetic Predisposition to Disease; D006239:Haplotypes; D006801:Humans; D053762:Interleukin-12 Subunit p40 / Q000235:genetics*; D053583:Interleukin-1beta / Q000235:genetics*; D008297:Male; D008875:Middle Aged; D020641:Polymorphism, Single Nucleotide; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
chemical_list: C500879:IL12B protein, human; D053762:Interleukin-12 Subunit p40; D053583:Interleukin-1beta; D014409:Tumor Necrosis Factor-alpha