There is considerable interest in the role of different candidate loci in the development of asthma. This study investigates the association between asthma severity and previously identified polymorphisms at two sites within the β2-adrenergic receptor (β2AR) gene: the Arg16→Gly16 and Gln27→Glu27 alleles.
Restriction enzyme analysis of amplified β2AR gene products (PCR-RFLP) was used to analyse the frequency of the Arg16→Gly16 and Gln27→Glu27 polymorphisms within the β2AR gene in 95 severe asthmatic patients (with a markedly increased risk of death from asthma), 59 mild asthmatic patients, and a control group of 92 nonasthmatic subjects.
The Gly16 polymorphism was significantly associated with asthma severity with odds ratios (95% CI) for the Gly16 allele being 1.56 (1.02–2.40, P = 0.04) and 0.98 (0.61–1.57, P = 0.92) for the severe and mild asthma groups, respectively. The corresponding odds ratios (95% CI) for Gly16 homozygotes were 1.91 (0.82–4.41, P = 0.13) and 0.82 (0.35–1.92, P = 0.65) for the severe and mild asthma groups, respectively. There was no significant association between either polymorphism at amino acid 27 and asthma or asthma severity.
We conclude that the polymorphisms of amino acids 16 and 27 of the β2AR gene are not associated with the development of asthma per se, but that the Gly16 polymorphism may play a role in the pathogenesis of asthma severity.