title: Influence of β(2)-adrenergic receptor polymorphism on methacholine hyperresponsiveness in asthmatic patients.
abstract: BACKGROUND
  We previously reported that the β(2)-adrenergic receptor (ADRB2) polymorphism had no effect on bronchial hyperresponsiveness (BHR) to methacholine in asthmatic patients. We have now replicated this analysis in a different and larger cohort of patients.
  
  
  OBJECTIVE
  To assess the effect of the ADRB2 polymorphism in methacholine-responsive patients with asthma.
  
  
  METHODS
  We conducted a retrospective analysis of the effects of ADRB2 haplotypes at position 16 (Gly/Arg) and 27(Gln/Glu) in 449 patients with a physician diagnosis of asthma who were responsive to methacholine (ie, provocation concentration that caused a decrease in forced expiratory volume in 1 second [FEV(1)] of 20% [PC(20)], <8 mg/mL).
  
  
  RESULTS
  No differences were found in age, FEV(1), or inhaled corticosteroid dose among the genotypes or haplotypes. No significant differences were found in methacholine PC(20) (ie, <8 mg/mL) between the separate genotypes at position 16 or 27 or between the haplotypes at positions 16/27 combined. In addition, no significant differences were found among individual genotypes when stratified according to severity of BHR using different doubling dilution cutoff points for methacholine PC(20) (ie, <4 mg/mL, <2 mg/mL, and <1 mg/mL).
  
  
  CONCLUSIONS
  We have confirmed in this replication study that common ADRB2 genotypes or haplotypes at positions 16/27 do not influence BHR in methacholine-responsive patients with asthma.
authors.affiliation: Asthma and Allergy Research Group, Division of Cardiovascular and Diabetes Medicine, Medical Research Institute, University of Dundee, Dundee, Scotland.
authors.forename: Arvind
authors.initials: A
authors.lastname: Manoharan
authors.forename: William J
authors.initials: WJ
authors.lastname: Anderson
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Lipworth
mesh_terms: D000328:Adult; D001249:Asthma / Q000175:diagnosis / Q000503:physiopathology*; D016535:Bronchial Hyperreactivity / Q000235:genetics*; D001985:Bronchial Provocation Tests; D015331:Cohort Studies; D018450:Disease Progression; D005260:Female; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D008875:Middle Aged; D011110:Polymorphism, Genetic; D018343:Receptors, Adrenergic, beta-2 / Q000235:genetics*; D012189:Retrospective Studies
chemical_list: D018343:Receptors, Adrenergic, beta-2; D016210:Methacholine Chloride