title: Clarification of the risk of chronic obstructive pulmonary disease in α1-antitrypsin deficiency PiMZ heterozygotes.
abstract: BACKGROUND
  Severe α1-antitrypsin deficiency (typically PiZZ homozygosity) is associated with a significantly increased risk of airflow obstruction and emphysema but the risk of chronic obstructive pulmonary disease (COPD) in PiMZ heterozygotes remains uncertain.
  
  
  OBJECTIVE
  This was a family-based study to determine the risk of COPD in PiMZ individuals.
  
  
  METHODS
  We compared 99 PiMM and 89 PiMZ nonindex subjects recruited from 51 index probands who were confirmed PiMZ heterozygotes and also had a diagnosis of COPD Global Initiative for Chronic Obstructive Lung Disease stage II-IV. The primary outcome measures of interest were quantitative variables of pre- and post-bronchodilator FEV1/FVC ratio, FEV1 (liters), FEV1 (% predicted), forced expiratory flow midexpiratory phase (FEF25-75; liters per second), FEF25-75 (% predicted), and a categorical outcome of COPD.
  
  
  RESULTS
  PiMZ heterozygotes compared with PiMM individuals had a reduced median (interquartile range) post-bronchodilator FEV1 (% predicted) (92.0 [75.6-105.4] vs. 98.6 [85.5-109.7]; P = 0.04), FEV1/FVC ratio (0.75 [0.66-0.79] vs. 0.78 [0.73-0.83]; P = 0.004), and FEF25-75 (% predicted) (63.84 [38.45-84.35] vs. 72.8 [55.5-97.7]; P = 0.0013) compared with PiMM individuals. This effect was abrogated in never-smoking and accentuated in ever-smoking PiMZ individuals. PiMZ heterozygosity was associated with an adjusted odds ratio for COPD of 5.18 (95% confidence interval, 1.27-21.15; P = 0.02) and this was higher (odds ratio, 10.65; 95% confidence interval, 2.17-52.29; P = 0.004) in ever-smoking individuals.
  
  
  CONCLUSIONS
  These results indicate that PiMZ heterozygotes have significantly more airflow obstruction and COPD than PiMM individuals and cigarette smoke exposure exerts a significant modifier effect.
authors.affiliation: 1 Respiratory Research Division, Department of Medicine, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin, Ireland; and.
authors.forename: Kevin
authors.initials: K
authors.lastname: Molloy
authors.forename: Craig P
authors.initials: CP
authors.lastname: Hersh
authors.forename: Valerie B
authors.initials: VB
authors.lastname: Morris
authors.forename: Tomás P
authors.initials: TP
authors.lastname: Carroll
authors.forename: Catherine A
authors.initials: CA
authors.lastname: O'Connor
authors.forename: Jessica A
authors.initials: JA
authors.lastname: Lasky-Su
authors.forename: Catherine M
authors.initials: CM
authors.lastname: Greene
authors.forename: Shane J
authors.initials: SJ
authors.lastname: O'Neill
authors.forename: Edwin K
authors.initials: EK
authors.lastname: Silverman
authors.forename: Noel G
authors.initials: NG
authors.lastname: McElvaney
mesh_terms: D000328:Adult; D000368:Aged; D005260:Female; D005541:Forced Expiratory Volume; D059647:Gene-Environment Interaction; D005819:Genetic Markers; D006579:Heterozygote; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010641:Phenotype; D029424:Pulmonary Disease, Chronic Obstructive / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects; D013147:Spirometry; D011795:Surveys and Questionnaires; D014797:Vital Capacity; D000515:alpha 1-Antitrypsin / Q000235:genetics*; D019896:alpha 1-Antitrypsin Deficiency / Q000150:complications / Q000235:genetics*
chemical_list: D005819:Genetic Markers; C043392:SERPINA1 protein, human; D000515:alpha 1-Antitrypsin