Beta2 adrenergic receptor (ADRβ2) haplotype pair (2/4) is associated with severe asthma.

BACKGROUND: β2 adrenergic receptor (ADRβ2) polymorphisms including ADRβ2+46G>A have been reported to cause adverse outcomes in mild asthmatics. The extent to which ADRβ2 polymorphisms and in particular their haplotypes contribute to severe asthma is unknown. OBJECTIVE: To determine the association of ADRβ2 polymorphisms and haplotypes with asthma severity. METHODS: Caucasians (n = 2979) were genotyped for 11 ADRβ2 polymorphisms. The cohort (mean age 39.6, 60% female) included 2296 non-asthmatics, 386 mild asthmatics, 172 moderate asthmatics and 125 severe asthmatics. Haplotype frequency and haplotype pair for each subject was determined using the PHASE algorithm. RESULTS: The three asthmatic cohorts were comparable in age and gender but were distinguishable from each other in terms of symptoms, spirometry, medication use and health care utilisation (p