SERPINA1 and chronic obstructive pulmonary disease: Consistent with this kinetic, we identified detectable AAT in 0.1% to 13.4% of pro-SFTPC-positive cells in ZZ-AATD lung parenchyma, compared with extremely rare (wild-type COPD) or absent (non-lung disease control participants) AAT+/pro-SFTPC+ cells in non-AATD tissue (Fig 1G-H).