Patients with severe AATD had more dyspnea (MRC-m) ≥ 2 (OR 2.56, p < 0.001), were more likely to have phenotype of exacerbator chronic bronchitis (OR 3.34, p = 0.023) and were less likely to be active smokers (OR 0.58, p = 0.023) than individuals with normal AAT levels ≥116 mg/dL. This evidence concerns the gene SERPINA1 and alpha 1-antitrypsin deficiency.