SERPINA1 and chronic obstructive pulmonary disease: The therapeutic potential of gene therapy has been further investigated in various respiratory diseases (Figure 1), including PAH, idiopathic pulmonary fibrosis (IPF), asthma, CF, chronic obstructive pulmonary disease (COPD), alpha-1 antitrypsin (AAT) deficiency, lung cancer, and coronavirus disease 2019 (COVID-19).