Impact of 27Gln\Glu Polymorphisms of β2-Adrenergic Receptor Gene on Pulmonary Function in Asthmatic Children Treated with Nebulized Salbutamol

Background: The β2-adrenergic receptor gene is a typical candidate for the study of genetic polymorphism. Many patients with asthma do not respond to β2-agonist; in addition, a wide interindividual variability in pharmacological response exists, likely because of the interaction between clinical, environmental, and genetic factors. Methods: A total of 80 children (55 boys and 25 girls) with mild-moderate acute asthma attacks, ages range between 5 and 18 years, attended the Asthma Clinic at Karbala Teaching Hospital for Children were included in this study. Spirometry (Spirolab III) was used for lung function assessment before and after treatment with nebulized salbutamol, and allele-specific polymerase chain reaction was performed to determine single nucleotide polymorphisms (SNP) of β2-adrenergic receptor gene at nucleic acid 79 (27 amino acid position). Results: The effect of treatment with nebulized salbutamol on lung function in asthmatic children having different genotypes of 27Gln\Glu SNP demonstrated that patients having GG and CG genotypes showed significant improvement (P < 0.05) in forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC), FEV1/FVC ratio, and FEV1% predicted after treatment, while patients having CC genotype showed significant improvement (P < 0.05) in FEV1, FVC, and FEV1% predicted after treatment with nebulized salbutamol without significant improvement in FEV1/FVC ratio. Patients having CG genotype of 27Gln\Glu SNP showed highest change (increase) in FEV1 (185.38 ± 174.93 ml) and in FEV1% predicted (14.96 ± 15.45%) after treatment with nebulized salbutamol in comparison with other genotype groups although this change was not statistically significant between groups. Conclusion: Asthmatic children having CG and GG genotypes of β2-adrenergic receptor gene (27Gln\Glu) showed better improvement in lung function after treatment with nebulized salbutamol in comparison with those having CC (27Gln\Glu) genotype during mild-to-moderate acute asthma attacks.