ANALYSIS OF THE ASSOCIATION OF BRONCHIAL ASTHMA CLINICAL COURSE WITH Arg16Gly POLYMORPHIC VARIANT IN THE β2-ADRENOCEPTOR GENE
Authors: Kachkovska V.V. , Prystupa L.N. 
Published: July 2021

Relevance. The relevance of the study of Arg16Gly polymorphism of the β2-adrenoceptor (β2-AR) gene is due to the fact that a number of studies have proven its role in the development of bronchial asthma (BA), bronchial hyperactivity, the effectiveness of basic treatment. However, these associations show low reproducibility in various studies, so the question of the possibility of clinical application of the results of genetic testing for Arg16Gly polymorphic variant of the β2-AR gene remains unanswered. The main reasons why the clinical significance of this polymorphism is not confirmed in various studies are - population heterogeneity, insufficient sample size, improper characterization of comparison groups.

Objective: to study the association of Arg16Gly polymorphism in the β2-adrenoceptor gene with BA clinical course taking into account the age of onset.

Materials and methods. We examined 553 BA patients (group I included 282 patients with late-onset asthma and group II included 271 patients with early-onset asthma) and 95 apparently healthy individuals. The study has been approved by the Bioethics Committee of Medical Institute of Sumy State University. Arg16Gly polymorphism in the β2-АR gene (rs1042713) was determined using polymerase chain reaction-restriction fragment length polymorphism analysis. Statistical analysis of obtained results was performed using SPSS–17 program.

Results. There was no significant difference in the distribution of genotypes for Arg16Gly polymorphism in the β2-AR gene depending on asthma severity with no regard for the age of onset (χ2 = 5.14; p = 0.27). With regard for the age of onset, we found out that early-onset BA was linked to a difference in genotype distribution for this polymorphic variant in patients with severe and non-severe course (χ2 = 14.76; р = 0.001). The frequency of Gly/Gly genotype was higher in patients with severe course (41.4%) as compared to patients with mild course (16.4%), while the frequency of Arg/Arg (32.9%) and Arg/Gly (50.7%) genotypes was higher in patients with mild asthma as compared to patients with severe course (24.3% and 34.3%). There was no significant difference in the distribution of genotypes in patients with late-onset asthma with regard to course severity (χ2 = 4.94; p = 0.084).

The relative risk of severe course for early-onset asthma was 3.84 times higher (95% CI 2.11–7.36; p = 0.001) in the recessive model, 2.58 times higher (95% CI 1.53–4,37, p = 0.001) in the dominant model, and 2.16 times (95% CI 1.56–3.04) higher in the additive model. In patients with late-onset asthma, no association was found in all models.

Conclusions. There was no significant difference in the distribution of genotypes for Arg16Gly polymorphism in the β2-AR gene depending on asthma severity with no regard for the age of onset. When adjusted for the age of onset, the analysis revealed a difference in genotype distribution for this polymorphic variant in patients with severe and non-severe course having early-onset BA (р = 0.001). The frequency of Gly/Gly genotype was higher in patients with severe course as compared to patients with mild course. For patients with late-onset asthma, no differences were found (p = 0.084). Heterozygous and homozygous Gly allele carriers have a higher risk of early-onset asthma only.