title: HLA class II DRB1, DQB1 and DPB1 genotypic associations with peanut allergy: evidence from a family-based and case-control study.
abstract: BACKGROUND
  Peanut is one of the most common foods provoking allergic reactions and is the most frequent cause of fatal and near-fatal food-induced anaphylaxis. However, as yet, little is known of the genetic and immunological mechanisms which underly peanut allergy.
  
  
  OBJECTIVE
  Based on findings in other allergic diseases, we have investigated whether particular human leucocyte antigen (HLA) class II genetic polymorphisms contribute to the development of peanut allergy.
  
  
  METHODS
  All individuals from 37 families each containing one or more peanut allergic individuals, plus nine unrelated patients (161 individuals in total, defined as the study group) were typed for the HLA class II DRB1, DQB1 and DPB1 loci, by PCR-based techniques. Genotype frequencies were compared with those found in 293 unrelated controls.
  
  
  RESULTS
  Four class II genotypes (DRB1*08 (13.7% vs 4.8%; Pc = 0.026), DRB1*08/12 tyr 16 (22.4% vs 8.2%; Pc = 0.021), DQB1*04 (12.2% vs 2.7%; Pc = 0.0026) and DPB1*0301 (49.1 vs 22.5%; Pc = 0.00062)) were present at a significantly higher frequency in the study group compared with controls. Three of these genotypes (DRB1*08 (18.0%; Pc = 0.027), DRB1*08/12 tyr16 (24.0%; Pc = 0.029) and DQB1*04 (16.7%; Pc = 0.0029)) were also significantly increased in peanut allergic individuals compared with controls. In addition, two genotypes (DPB1*0101 and 0201) were significantly decreased in frequency in the overall study group, but not specifically in peanut allergic individuals.
  
  
  CONCLUSIONS
  While other genetic factors may be important, results from this study indicate that HLA class II genetic polymorphism may play a role in determining susceptibility to peanut allergy.
authors.affiliation: Wessex Histocompatibility Laboratory, Southampton General Hospital, UK.
authors.forename: W M
authors.initials: WM
authors.lastname: Howell
authors.forename: S J
authors.initials: SJ
authors.lastname: Turner
authors.forename: J O
authors.initials: JO
authors.lastname: Hourihane
authors.forename: T P
authors.initials: TP
authors.lastname: Dean
authors.forename: J O
authors.initials: JO
authors.lastname: Warner
mesh_terms: D010367:Arachis / Q000009:adverse effects* / Q000276:immunology; D016022:Case-Control Studies; D004247:DNA / Q000097:blood; D005192:Family Health; D005512:Food Hypersensitivity / Q000235:genetics*; D005787:Gene Frequency / Q000235:genetics; D005802:Genes, MHC Class II / Q000235:genetics*; D005819:Genetic Markers / Q000235:genetics; D005838:Genotype; D006682:HLA-DP Antigens / Q000097:blood / Q000235:genetics; D059868:HLA-DP beta-Chains; D006683:HLA-DQ Antigens / Q000097:blood / Q000235:genetics; D059866:HLA-DQ beta-Chains; D006684:HLA-DR Antigens / Q000097:blood / Q000235:genetics; D059811:HLA-DRB1 Chains; D000949:Histocompatibility Antigens Class II / Q000097:blood / Q000235:genetics*; D006801:Humans
chemical_list: D005819:Genetic Markers; D006682:HLA-DP Antigens; D059868:HLA-DP beta-Chains; C071170:HLA-DPB1 antigen; D006683:HLA-DQ Antigens; D059866:HLA-DQ beta-Chains; C069051:HLA-DQB1 antigen; D006684:HLA-DR Antigens; D059811:HLA-DRB1 Chains; D000949:Histocompatibility Antigens Class II; D004247:DNA