Beta2-adrenoceptor polymorphisms are in linkage disequilibrium, but are not associated with asthma in an adult population

Abstract

Objective: To determine the association between the beta2-adrenoceptor polymorphisms at amino acids 16 and 27 and markers of allergic disease and asthma per se in a random adult population, and to determine the degree of linkage disequilibrium existing between polymorphisms at amino acid positions 16, 27, 164 and nucleic acid residue 523.

Methods: We measured serum IgE, skin-prick test positivity, atopy, bronchial hyperreactivity, wheeze and asthma (self-reported and doctor-diagnosed), and determined beta2-adrenoceptor genotype by allele specific oligonucleotide hybridization, in 630 adults aged between 18 and 70, selected from the electoral role in a local health authority in Nottingham.

Results: Homozygotes for the Glycine 16 polymorphism had a significantly higher incidence of atopy (chi2=6.44 (Pearson's), P=0.04). We also observed a significant association between the Glycine 16 allele and atopy (chi2=4.13 (Pearson's), P=0.04), when we assumed the Glycine 16 allele to operate in a dominant mode. No other significant associations between beta2-adrenoceptor polymorphisms and markers of allergic disease and asthma per se were observed. Marked linkage disequilibrium exists between the beta2-adrenoceptor polymorphisms at amino acid 16 and 27 (D=0.38, chi2 P<0.0001), and between the beta2-adrenoceptor polymorphisms at amino acid 27 and nucleic acid residue 523 (C-A) (D=0.36, chi2 P<0.0001).

Conclusion: There is no consistent association between beta2-adrenoceptor polymorphisms and the risk of developing allergic disease or asthma per se in this adult sample. Marked linkage disequilibrium exists between the amino acid 16 and 27 polymorphisms, and also between the amino acid 27 polymorphism and the nucleic acid residue 523 (C-A) polymorphism. This polymorphism accounts for the Ban 1 RFLP previously described at the beta2-adrenoceptor locus on chromosome 5q 31.