ANALYSIS OF THE ASSOCIATION OF BRONCHIAL ASTHMA CLINICAL COURSE WITH Arg16Gly POLYMORPHIC VARIANT IN THE β2-ADRENOCEPTOR GENE

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.

ARG16GLY POLYMORPHISM IN THE Β2-ADRENOCEPTOR GENE IN PATIENTS WITH BRONCHIAL ASTHMA

The aim: The objective of the study was to analyze the frequency of Arg16Gly polymorphism in the β2 -adrenoceptor (β2 -АR) gene in patients with bronchial asthma (BA) and to assess the association of the polymorphism with BA risk. Materials and methods: We examined 553 BA patients and 95 apparently healthy individuals. 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: It was established that distribution of Arg/Arg, Arg/Gly, and Gly/Gly genotypes for Arg16Gly polymorphism in the β2 -АR gene was 44.2%, 40.0%, 15.8% in the control group vs. 31.3%; 45.7% and 23.0 among BA patients, respectively (χ2 = 6.59; р = 0.037). No significant difference was observed with regards to the distribution of genotypes for Arg16Gly polymorphism in the β2 -АR gene in men and women controls (χ2 = 4.05; р = 0.13) and BA patients (χ2 = 4.34; р = 0.11). BA risk was 1.74 times higher in the minor allele carriers (Arg/Gly + Gly/Gly genotypes) for Arg16Gly polymorphism in the β2 -АR gene. Conclusions: Analysis of Arg16Gly polymorphic variants in the β2-AR gene showed a statistically significant difference in the distribution of Arg/Arg, Arg/Gly, and Gly/Gly genotypes in patients with BA and apparently healthy individuals due to the higher frequency of Arg/Arg genotype in controls and higher frequency of Gly/Gly genotype in patients with asthma. No difference with regard to gender was found in the distribution of genotypes.

ADRB2 Arg16Gly Polymorphism and Pulmonary Function Response of Inhaled Corticosteroids plus Long-Acting Beta Agonists for Asthma Treatment: A Systematic Review and Meta-Analysis

Background. The beta-2 adrenergic receptor (ADRB2) Arg16Gly polymorphism may alter the bronchodilation response to long-acting beta2-agonists, thereby influencing the clinical effectiveness of LABAs plus corticosteroids (ICS) treatment. But the results of individual studies are inconclusive. Methods. A systematic search was conducted in PubMed, Embase, the Cochrane Database, WHO International Clinical Trials Registry Platform, Chinese National Knowledge Infrastructure, Wanfang, Chinese BioMedical Literature Database, and VIP databases. The meta-analysis was performed with RevMan statistical software (version 5.2), and potential publication bias was estimated by Egger’s test using STATA (version 12.0), with p<0.05 indicating significant publication bias. Results. We found 5 cohort studies with a total of 632 patients and included them in the meta-analysis. There are no significant differences in pulmonary function response between patients with the Arg/Arg and Arg/Gly phenotype (SMD −0.04, 95% CI −0.45 to 0.37; p=0.84). There were also no significant differences in the pulmonary function response between patients with the Arg/Arg and Gly/Gly phenotype (MD −0.03, 95% CI −0.07 to 0.02; p=0.28). Conclusions. Our systematic review and meta-analysis suggest that ADRB2 Arg16Gly polymorphism is not associated with pulmonary response to asthma treatment with ICS plus LABAs.

Arginine 16 Glycine Polymorphism inβ2-Adrenergic Receptor Gene Is Associated with Obesity, Hyperlipidemia, Hyperleptinemia, and Insulin Resistance in Saudis

Background. Several studies have shown an association between codon 16 polymorphism of theβ2AR gene and obesity.Methods. We studied the association between Arg16Gly polymorphism and obesity and its influence on anthropometric parameters, lipids, insulin resistance and leptin in Saudi individuals. The study group included 329 individuals (males: 109 and females: 220). Metabolic parameters, including glucose, lipids, insulin, and leptin were analyzed and anthropometric parameters including waist and hip circumference, waist/hip (W/H) ratio, and body mass index (BMI) were measured and HOMA-IR was calculated. Genotyping was conducted by DNA sequencing of 353 bp fragments, carrying the Arg16Gly polymorphic site.Results and Conclusion. Overweight and obese subjects had a significantly higher frequency of Gly16 (0.375 and 0.38, resp.) compared with normal-weight subjects (0.200). In addition, subjects carrying Gly16 allele regardless of their BMI had greater waist and hip circumference, W/H ratio, plasma lipids, leptin, glucose level, and insulin resistance as judged from the HOMA-IR, compared to those with the wild-type allele. The findings of this study show a significant association between the Arg16Gly polymorphism inβ2AR gene and the development of insulin resistance, overweight, and obesity in Saudi populations with an influence on the levels of lipid and leptin.