CLINICAL COURSE OF OBESITY-ASSOCIATED ASTHMA DEPENDING ON THE GLN27GLU POLYMORPHIC VARIANT OF THE β2-ADRENORECEPTOR GENE, TAKING INTO ACCOUNT THE AGE OF ONSET

Abstract

Introduction. Studies have shown that bronchial asthma (BA) associated with obesity has a more severe course, lower control, more frequent cases of low efficacy of basic treatment, and exacerbations. Two phenotypes have been distinguished in BA-obesity comorbidity based on age of onset: early atopic and late non-atopic. It is known that genetic factors associated with β2-adrenoceptor (AR) genes are important in the development of both asthma and obesity. The purpose of the study aimed to analyze the association of the Gln27Glu polymorphism of the β2-adrenoceptor gene with the severity of the course of bronchial asthma with obesity, taking into account the age of its onset. Research material and methods. 195 asthma patients with obesity consented for the study participation were examined. The control group consisted of 95 practically healthy people. Patients were divided into two clinical groups depending on the age of onset of BA: the first group included 100 patients with an early onset, the second group - 95 patients with a late onset.  The diagnosis and treatment of asthma followed the guidelines of the Global Initiative for Asthma (2016) and its updated versions. The study was approved by the Bioethics Commission of the Educational and Scientific Medical Institute of Sumy State University. Determination of the Gln27Glu polymorphism of the β2-AR gene (rs1042714) was performed using the polymerase chain reaction with the subsequent analysis of restriction fragments. Statistical analysis of the obtained results was carried out using the SPSS-17 program. Pearson's chi-squared test was used to compare genotype distributions between experimental groups. To determine the risk of BA and obesity, odds ratios and 95% confidence intervals were calculated for dominant, recessive, superdominant, and additive models of inheritance. Their relevance was assessed using the Akaike information criterion. All tests were two-sided, and values p < 0.05 were considered statistically significant. Research results. The frequency of Gln/Gln, Gln/Glu and Glu/Glu genotypes according to the Gln27Glu polymorphism of the β2-AR gene in patients with early-onset obesity-associated asthma was 70.0; 25.0; 5.0% with a mild course and 55.0; 36.2; 8.8% with severe (χ2 = 1.49; p = 0.473); and with a late debut - 50.0; 43.8; 6.2% with mild and 54.0%; 31.7; 14.3%, respectively, with severe (χ2 = 2.10; p = 0.350). Despite the absence of a probable difference in the distribution of genotypes depending on the severity of the course, it was found that the frequency of homozygotes for the minor allele was 1.8 times higher in patients with a severe course of early BA and 2.3 times higher in late BA compared to that in patients with mild BA course. The risk of early-onset BA with obesity and a severe course showed no association in all models of inheritance, and in patients with late-onset BA, there was a 1.66-fold increase (95% CI (1.03 – 2.72), p = 0.04) in the additive inheritance model (p = 0.04). Conclusions. There are no statistically significant differences in the distribution of genotypes according to the Gln27Glu polymorphism of the β2-AR gene depending on the severity of the course of early and late BA with obesity. The risk of developing a severe course of early BA did not depend on the Gln27Glu polymorphism of the β2-AR gene, and late BA increased by 1.66 times in the additive model of inheritance.