Background: The β2-adrenergic receptor gene is one of the most extensively studied genes with respect to asthma prevalence and severity. The Arg16Gly and Gln27Glu polymorphisms in the β2-adrenergic receptor gene cause changes in the amino acids sequence of the receptor which may cause alteration in response to bronchodilators and the risk of asthma.
Objective: The purpose of the study was to determine the association between β2-adrenergic receptor gene polymorphisms and asthma risk, severity and response to therapy.
Subjects and methods: 58 asthmatic patients and 38 healthy subjects were included. The β2-adrenergic receptor polymorphisms genotyping was done using Real-Time polymerase chain reaction.
Results: The allelic frequencies for the Arg16Gly polymorphism were 15.5%, 48.3%, and 36.2% for the homozygous A wild, heterozygous, and homozygous G mutant alleles in asthmatics (P < 0.01) and 5.3%, 47.4%, and 47.4% in healthy subjects (P < 0.01). For the Gln27Glu polymorphism, the allelic frequencies for the homozygous C wild, heterozygous and homozygous G mutant alleles were 51.7%, 41.4%, and 6.9% in asthmatics (P < 0.01) and 44.7%, 39.5%, and 15.8% in healthy subjects (P < 0.01). The heterozygous Arg16Gly and Gln27Glu were found in most of severe asthma cases (7/13, 53.8% each). While homozygous wild and mutant seemed to be protective and associated with mild disease in both alleles. Finally, 75% of Arg16Gly heterozygous group were good responders (P < 0.01), 81% of homozygous G mutant were bad responders. For Gln27Glu polymorphism, 60% of C wild group were good responders and 75% of G mutant group were bad responders.
Conclusions: The findings suggest that the Arg16Gly and Gln27Glu polymorphisms in the β2-AR gene are associated with asthma severity and response to therapy and might be used in personalized treatment for these patients in the future. This work is registered in ClinicalTrial.gov with ID: NCT03118869.
Keywords: Asthma; Egyptian; Polymorphisms; Response; Severity; β2-adrenoreceptor.