SERPINA1 and pulmonary emphysema: Secondary objectives were to evaluate (1) emphysema type (centrilobular, panlobular or paraseptal), distribution (upper, lower lobes, or no predominance) and extension, (2) lung function in the whole population and in participants with emphysema and (3) the frequency of unexplained emphysema, defined as low tobacco exposure (active smoking < 5 pack-years and no significant passive smoking), no exposure to noxious particles, no AAT deficiency and no pathogenic variant in PTPN6 gene.