ABSTRACT
BACKGROUND: In a previous linkage analysis, a marker locus on chromosome 5q31-33 showed evidence of linkage to bronchial responsiveness to methacholine and atopy. The beta2-adrenoceptor (beta2AR) gene is located on chromosome 5q32 and is considered to be a candidate gene in the development of asthma phenotype. OBJECTIVE: The aim of this study was to evaluate the association between asthma phenotypes and beta2AR polymorphism at amino acids 16 and 27. METHODS: From the general population, 440 unrelated Korean subjects were randomly selected, and asthma phenotypes were determined using a questionnaire, skin prick tests, and methacholine bronchial provocation tests. Haplotypes of 16 and 27 polymorphisms on the beta2AR gene were determined using PCR-based methods. RESULTS: Frequencies of haplotypes of beta2AR gene for polymorphic positions 16 and 27 were Arg16-Gln27:53.2%, Gly16-Gln27:36.4%, Arg16-Glu27:0.1% and Gly16-Glu27:10.3%. No significant association was found between haplotype of beta2AR gene and asthma phenotypes. Among the atopic subjects, however, we observed that Arg16-Gln27 and Gly16-Gln27 haplotypes were significantly associated with nocturnal cough. There was linear association between the development of nocturnal cough and the number of Arg16-Gln27 and Gly16-Gln27 haplotypes, respectively. CONCLUSION: This study demonstrates that the linkage of a gene marker on chromosome 5q31-33 with atopy and bronchial responsiveness is not related with genetic variations in the beta2AR gene. However, beta2AR polymorphisms may play an important role in the expression of nocturnal cough in atopic subjects.