While people heterozygous for the gene encoding alpha-1 antitrypsin (AAT) deficiency who are cigarette smokers show a higher risk for COPD, the mechanism of the increased risk is unknown, and a recent study has suggested that people heterozygous for AAT may be a subset of COPD disease (Ghosh et al., 2022). This evidence concerns the gene SERPINA1 and alpha 1-antitrypsin deficiency.