Objective: To investigate whether the polymorphisms of beta2-adrenergic receptor (beta2-AR) at position 16, 27, 164 are associated with asthma in Northern Chinese subjects.
Methods: Genomic DNA was collected from unrelated Northern Chinese population of Han ethnicity, including 125 unrelated asthmatic individuals and 96 healthy controls. Beta2-AR genes at position 16, 27, 164 were amplified by using restriction fragment length polymorphism (RFLP) and allelic specific polymerase chain reaction methods. All asthmatics had their serum IgE (total and specific) antibody or skin-prick test measured, bronchial reactivity to methacholine (Mch) and bronchial reversibility by beta2-agonist evaluated.
Results: (1) The frequency of Gly 16 homozygous was significantly higher in the asthmatic group than that in healthy controls (22.4% vs. 8.3%, P < 0.05), OR was 2.9 with 95% CI 1.26-6.78. The proportion of Gly 16 allele was also higher in asthmatics than that in control (0.46 vs. 0.36, P < 0.05); Gly16 homozygous was not independently associated with asthma pathogenesis (P = 0.21, OR 0.42 with 95% CI 0.11-1.61). (2) Of 51 night attack patients, 18 carrying Gly16 homozygosity, if compared with 10 of 74 nonnocturnal asthmatics carrying this genotype, there was significant difference between these two groups (35.3% vs. 13.5%, P < 0.01). (3) The average dose of PD20-Mch was significantly lower in patients carrying Gln 27 homozygous than those carrying homozygous Glu 27 and Gln/Glu 27 heterozygous (0.2 +/- 0.3, 1.6 +/- 0.8, and 2.1 +/- 3.0 micromol/L, P < 0.05).
Conclusion: Beta2AR gene polymorphisms might confer susceptibility to asthma in Chinese Northern patients. Beta2-AR gene, coordinated with other candidate loci, plays a role in the development of asthma.