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 gene discussed is IREB2; the disease is chronic obstructive pulmonary disease.