Relation between Substitution of Threonine for Isoleucine at Β2 Adrenergic Receptor on Bronchial Asthma in Children

Introduction: Pediatric asthma is a complex disorder involving immunologic, genetic, environmental and other factors. Objective: To evaluate the role of substitution of threonine for isoleucine at codon 164 on bronchial asthma susceptibility, severity and response to short- and long- term acting β2-adrenergic receptor agonists in children. Patients and Methods: This study was a prospective case control study, which was done in Pediatric Department of Zagazig University Hospital from Pulmonology Clinic in the period from February 2016 to February 2018. 100 children were included, 50 of them had asthma with bronchodilator and their ages ranged from 5 to 12 years (25 males and 25 females) with the mean age of 6.8 ± 2.5 years. In addition, 50 healthy age and sex matched worked as control children. All studied groups were subjected to full history taking, clinical examination, pulmonary function tests, total serum IgE and identification of adrenergic β2 receptor (ADRβ2) substitution of threonine for isoleucine at codon 164 polymorphism. Results: In this study, there was a significant association between homozygous isoleucine and increase incidence of asthma, this mean that the gene gives harmful effect when it is in a homozygous form. However, there was no statistically significant difference between asthma severity and gene polymorphism (CC, CT and TT). Conclusion: In the present study ADRβ Thr164Ile polymorphism is reported as an important variant at salbutamol refractoriness in sever asthmatics. In addition, the polymorphism form is susceptible variant to develop asthma risk.