SERPINA1 and chronic obstructive pulmonary disease: Specific risk factors we included were pre-existing lung disease (defined as any of asthma, alpha-1-antitrypsin, emphysema/COPD, cystic fibrosis, interstitial lung disease, pulmonary alveolar proteinosis, pulmonary fibrosis, sarcoidosis, silicosis), diabetes, HIV, end-stage renal disease, collagen vascular disease, and history of transplant or cancer.