Moreover, as the mean age was significantly higher in COPD+ (n = 30, mean age ± SD: 70 ± 7 years old) than in COPD− (n = 85, mean age ± SD: 63 ± 9 years old) (p < 0.001), age-related changes in SERPINA1 promoter methylation of ACS patients were assessed. Here, SERPINA1 is linked to chronic obstructive pulmonary disease.