The major function of AAT in the lungs is to protect the connective tissue from HNE released from triggered neutrophils, as supported by the development of pulmonary emphysema early in life in subjects affected by severe inherited deficiency of AAT.14 In the majority of humans, the lungs are defended from HNE attack by normal AAT plasma levels ranging from 85 to 250 mg/dl.15 Although AAT is a well-known acute phase reactant, this wide variability in its normal plasma level mostly reflects the marked pleomorphism of the glycoprotein. Here, SERPINA1 is linked to pulmonary emphysema.