title: Genetic and environmental contributions to allergen sensitization in a Chinese twin study.
abstract: BACKGROUND
  Allergic disease is on the rise worldwide. Effective prevention of allergic disease requires comprehensive understanding of the factors that contribute to its intermediate phenotypes, such as sensitization to common allergens.
  
  
  OBJECTIVE
  To estimate the degree of genetic and environmental contributions to sensitization to food and aeroallergens.
  
  
  METHODS
  Sensitization was defined as a positive skin prick test to an allergen. We calculated the zygosity-specific concordance rates and odds ratios (ORs) for sensitization to food and aeroallergens in 826 Chinese twin pairs [472 monozygotic (MZ) and 354 dizygotic (DZ)] aged 12-28 years. We also applied structural equation modelling procedures to estimate genetic and environmental influences on sensitization.
  
  
  RESULTS
  The concordance rates and risk of sensitization in one twin given the presence vs. the absence of sensitization in the other twin were higher in MZ twins than those in DZ twins. However, a large number of MZ twins were discordant in sensitization to common allergens. These observations suggest both genetic and environmental factors influence sensitization. Consistently, the estimated heritability and individual environmental components of the liability to sensitization ranged from 0.51 to 0.68 and 0.32 to 0.49, respectively, based on the best-fitted structural equation model. We also observed high phenotypic correlations between sensitization to two aeroallergens (cockroach and dust mite: 0.83) and two food allergens (peanut and shellfish: 0.58), but only moderate correlations for the pairs between sensitization to a food and an aeroallergen (0.31-0.46). The shared genetic and environmental factors between paired sensitizations contribute to the observed correlations.
  
  
  CONCLUSIONS
  We demonstrated that sensitization to common food and aeroallergens were influenced by both genetic and environmental factors. Moreover, we found that paired allergen sensitizations might share some common sets of genes and environmental factors. This study underscores the need to further delineate unique and/or pleiotropic genetic and environmental factors for allergen sensitization.
authors.affiliation: Mary Ann and J. Milburn Smith Child Health Research Program, Department of Pediatrics, Northwestern University Feinberg School of Medicine, Children's Memorial Hospital, Chicago, IL, USA. xnliu@childrensmemorial.org
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: S
authors.initials: S
authors.lastname: Zhang
authors.forename: H-J
authors.initials: HJ
authors.lastname: Tsai
authors.forename: X
authors.initials: X
authors.lastname: Hong
authors.forename: B
authors.initials: B
authors.lastname: Wang
authors.forename: Y
authors.initials: Y
authors.lastname: Fang
authors.forename: X
authors.initials: X
authors.lastname: Liu
authors.forename: J A
authors.initials: JA
authors.lastname: Pongracic
authors.forename: X
authors.initials: X
authors.lastname: Wang
mesh_terms: D000293:Adolescent; D000328:Adult; D000485:Allergens / Q000235:genetics* / Q000276:immunology; D000818:Animals; D044466:Asian People / Q000235:genetics*; D002648:Child; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D004777:Environment; D005260:Female; D005500:Follow-Up Studies; D005512:Food Hypersensitivity / Q000453:epidemiology / Q000209:etiology / Q000235:genetics / Q000276:immunology; D006801:Humans; D006967:Hypersensitivity / Q000453:epidemiology / Q000209:etiology* / Q000235:genetics* / Q000276:immunology; D008297:Male; D016017:Odds Ratio; D010641:Phenotype; D011446:Prospective Studies; D012307:Risk Factors; D012680:Sensitivity and Specificity; D012727:Sex Characteristics; D012882:Skin Tests; D014429:Twins, Dizygotic / Q000235:genetics* / Q000276:immunology; D014430:Twins, Monozygotic / Q000235:genetics* / Q000276:immunology; D055815:Young Adult
chemical_list: D000485:Allergens