title: Gene-environmental interaction in asthma.
abstract: OBJECTIVE
  Asthma is likely to result from the effects of environmental stimuli in genetically susceptible individuals. This review summarizes recent studies of gene-environmental interaction in the pathogenesis of asthma, focusing on study designs.
  
  
  RESULTS
  Studies using genetic epidemiology, in-vitro and ex-vivo models and in-vivo model organisms demonstrate that gene-environmental interaction in involved in the development of asthma. Genetic association studies show a reduced risk of asthma and atopy with early life exposure to farming environments and house dust endotoxin, and increased risk with environmental tobacco smoke. These associations are modified by CD14 genotype. In people with a specific genotype, high environmental exposure may have the opposite effect of low exposure, possibly explaining some of the inconsistencies in previous studies. In-vitro and ex-vivo cell culture experiments show gene-environmental interactions with Toll-like receptor agonists, viruses and tobacco smoke. Interactions between innate immunity genes and exposure to endotoxin and air pollution have been observed in in-vivo mouse models.
  
  
  CONCLUSIONS
  The expanding evidence for gene-environmental interaction in asthma indicates the importance of measuring environmental factors in genetic studies of asthma. Understanding gene-environmental interaction would facilitate risk prognostication, improve preventive strategies and develop targeted interventions in people with asthma.
authors.affiliation: Department of Thoracic Medicine, The Prince Charles Hospital, Brisbane, Australia. Ian_Yang@health.qld.gov.au
authors.forename: Ian A
authors.initials: IA
authors.lastname: Yang
authors.forename: Santiyagu
authors.initials: S
authors.lastname: Savarimuthu
authors.forename: Samuel T
authors.initials: ST
authors.lastname: Kim
authors.forename: John W
authors.initials: JW
authors.lastname: Holloway
authors.forename: Scott C
authors.initials: SC
authors.lastname: Bell
authors.forename: Kwun M
authors.initials: KM
authors.lastname: Fong
mesh_terms: D000818:Animals; D001249:Asthma / Q000453:epidemiology / Q000235:genetics* / Q000276:immunology*; D004777:Environment; D020022:Genetic Predisposition to Disease; D006801:Humans