Aggarwal, NupurKoepke, JanineVarela Martinez, Maria del CarmenGolpon, HeikoStolk, JanJanciauskiene, SabinaKoczulla, RembertMatamala, NereaMartinez-Delgado, Beatriz2020-06-262020-06-262016Am J Respir Crit Care Med . 2016 May 1;193(9):1065-7.http://hdl.handle.net/20.500.12105/10601To the Editor: PiZZ (Glu342Lys) alpha-1 antitrypsin deficiency (A1ATD) is a typical genetic risk factor associated with the development of early-onset chronic obstructive pulmonary disease (COPD) with emphysema. Because A1AT is a major circulating inhibitor of serine proteases (serpin), a severe deficiency of this protein may lead to lung tissue damage by uncontrolled activity of neutrophil elastase, proteinase 3 (PRTN3), and other serine proteases. In general, a proteinase/antiproteinase imbalance is among potential mechanisms implicated in the pathophysiology of COPD (1). The importance of A1AT in maintaining protease–antiprotease homeostasis is also supported by a positive correlation between a recently described in vivo marker of neutrophil elastase activity (Aα-Val360) and disease severity in emphysema related to A1ATD (2). There is, however, considerable heterogeneity in the clinical expression among people with type ZZ A1ATD. Some develop emphysema in early adulthood (35–45 years of age), whereas others in late adulthood or not at all, and severity of symptoms also varies.engAMAgedFemaleHumansLeukocytes, MononuclearMaleMiddle AgedSerine Proteasesalpha 1-Antitrypsinalpha 1-Antitrypsin DeficiencyAtribución-NoComercial-CompartirIgual 4.0 Internacional2712870719391065-710.1164/rccm.201510-2062LE1535-4970American journal of respiratory and critical care medicineopen access