Exploring the Associations Between CHRNA5 and IREB2 Gene Polymorphisms and COPD in the Kazakhstan Population

Background/Objectives: Chronic obstructive pulmonary disease (COPD) is a progressive inflammatory lung disease characterized by irreversible airway obstruction. This study aims to investigate the associations between COPD and its phenotypes with polymorphic variants of the IREB2 and CHRNA5 genes in the Kazakhstan population. Methods: A case-control study was conducted involving 265 COPD patients and 267 controls. Genotyping of the IREB2 polymorphisms rs13180 and rs2568494, as well as CHRNA5 rs16969968 polymorphism, was performed using real-time polymerase chain reactions (Real-Time PCRs). Results: A higher frequency of the AA genotype of the IREB2 rs2568494 polymorphism was identified in COPD patients with moderate to very severe airflow obstruction (Chronic Obstructive Lung Disease (GOLD) stages II, III, and IV), with an odds ratio of 0.69 (95% CI = 0.23-2.10; Padj = 0.03). The IREB2 rs13180 polymorphism was significantly more frequent or prevalent in smokers and showed a correlation with FEV₁ (forced expiratory volume in one second) (β = 7.79, SE = 2.98, p = 0.01) and FEV₁/ FVC (forced vital capacity) (β = 9.51, SE = 2.95, p = 0.002). Additionally, the CC genotype of this polymorphism was associated with clinical manifestations of COVID-19 in COPD patients (χ²= 3,95, df = 2, p = 0.05). Conclusions: Our study identified a significant association between the IREB2 rs2568494 polymorphism and an increased risk of severe COPD. The IREB2 rs13180 polymorphism was linked to smoking behavior, as well as key lung function indicators, suggesting its potential role in disease progression and lung damage. Furthermore, the CC genotype of the IREB2 rs13180 polymorphism was associated with clinical manifestations of COVID-19 in COPD patients, indicating a potential impact of this genetic variant on susceptibility to viral infections in this population.