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SZ alpha-1 antitrypsin deficiency and pulmonary disease: more like MZ, not like ZZ
  1. Alessandro N Franciosi1,2,
  2. Tomás P Carroll1,3,
  3. Noel G McElvaney1,2
  1. 1 Irish Centre for Genetic Lung Disease, Royal College of Surgeons in Ireland, Dublin, Ireland
  2. 2 Department of Medicine, Beaumont Hospital, Dublin, Ireland
  3. 3 Alpha-1 Foundation Ireland, Royal College of Surgeons in Ireland, Dublin, Ireland
  1. Correspondence to Tomás P Carroll, Alpha-1 Foundation Ireland, Royal College of Surgeons in Ireland, Dublin, Ireland; tcarroll{at}


The ZZ genotype of alpha-1 antitrypsin deficiency (AATD) is associated with COPD regardless of smoking. Heterozygous MZ-AATD is recognised as a moderate deficiency state, increasing the risk of COPD only among smokers. The risk attributable to SZ-AATD remains debated. We compared 486 AATD-registry participants, to determine whether SZ-AATD was associated with pulmonary outcomes more comparable to MZ-AATD or ZZ-AATD. We found no significant differences between MZ and SZ individuals regardless of never-smoking/ever-smoking (p>0.05 for all). ZZ-AATD was associated with lower FEV1pp than SZ, regardless of never-smoking/ever-smoking, as well as an increased OR of lung-index status and visually defined emphysema on CT (p≤0.002 for all). In our registry cohort SZ-AATD is associated with a risk of lung disease comparable to MZ, not ZZ-AATD.

  • alpha1 antitrypsin deficiency

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  • TPC and NGM are joint senior authors.

  • Contributors ANF designed the study, performed statistical analyses and is the main author. TC consulted on study design, performed data curation and population building in the National Irish AATD Registry, coauthored the manuscript and is the study cosupervisor. NGM consulted on the study design, edited the manuscript and is the study cosupervisor.

  • Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval All participants of the National Irish AATD Registry provided written informed consent, which was approved by the Beaumont Hospital Research Ethics Committee (Ref. 05/03).

  • Provenance and peer review Not commissioned; externally peer reviewed.

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