Among COPD patients, lower lung function parameters, FEV1 % predicted (β = −5.42; 95% CI: −8.854–−1.977, p = 0.002) (Figure 2d), PEF % predicted (β = −3.73; 95% CI: −6.724–−0.731, p = 0.015), FVC % predicted (β = −6.09; 95% CI: −10.124–−2.063, p = 0.003), and FEV1 decline over years (β = 0.2; 95% CI: 0.042–0.359, p = 0.013) were significantly associated with higher HDAC2 levels (Figure 3a). The gene discussed is HDAC2; the disease is chronic obstructive pulmonary disease.