Genetic Polymorphisms of β2 Adrenergic Receptors Among Asthmatic Children

Introduction: There is a mounting evidence that polymorphisms in the β2AR gene are associated with significant variability in response to short-acting β2-agonists (SABA) and that a sub-set of patients with certain genotypes do not respond favorably to inhaled SABA.Aim: to assess the frequency of β2AR polymorphisms at position 16 in Egyptian asthmatic children and to discover the effect of these polymorphisms on asthma severity and response to salbutamol.Subjects and methods: A total of 100 Egyptian children with ages ranging from 4 to 12 years were enrolled in the study. They were divided into 2 groups; asthmatic group included 50 asthmatic children who were diagnosed according to GINA guidelines (2006), and a control group of 50 age and sex-matched healthy children. All participants were subjected to: history taking, thorough clinical examination, pulmonary function testing, and polymerase chain reaction plus restriction fragment assay (RFA) for beta two adrenergic receptors region (16) coding locus.Results: This study revealed that, homozygous Gly-16 genotype was found to have a higher frequency among patients with asthma vs. controls and also among patients with moderate/severe asthma vs. those with mild asthma. Regarding the response to treatment, patients with Arg-16 showed a significant improvement in FEV1% post bronchodilator with mean 17.3±7.86 in comparison to Arg16Gly and Gly16 genotypes.Conclusion, recommendations: This study has revealed that, genetic phenotype at codon 16 of β2AR gene may be determinant of asthma severity. However, we cannot exclude the possibility that other polymorphisms or complex haplotypes within the promoter and coding regions of the β2AR gene or adjacent genes might contribute to the present results Further studies are needed to demonstrate effects of polymorphisms of other genetic loci of β2AR on asthma severity and response to bronchodilators in our ethnic group.