title: Genetically increased antioxidative protection and decreased chronic obstructive pulmonary disease.
abstract: BACKGROUND
  Increased oxidative stress is involved in chronic obstructive pulmonary disease (COPD); however, plasma and bronchial lining fluid contains the antioxidant extracellular superoxide dismutase. Approximately 2% of white individuals carry the R213G polymorphism in the gene encoding extracellular superoxide dismutase, which increases plasma extracellular superoxide dismutase 10-fold and presumably also renders bronchial lining fluid high in extracellular superoxide dismutase.
  
  
  OBJECTIVE
  We tested the hypothesis that R213G reduces the risk of COPD.
  
  
  METHODS
  We studied cross-sectionally and prospectively (during 24 yr) 9,258 individuals from the Danish general population genotyped for R213G.
  
  
  METHODS
  We determined plasma extracellular superoxide dismutase concentration, pulmonary function and COPD diagnosed by means of spirometry or through national hospitalization and death registers.
  
  
  RESULTS
  In the general population, 97.5% were noncarriers, 2.4% were heterozygotes, and 0.02% were homozygotes. Among R213G noncarriers, extracellular superoxide dismutase plasma concentration was 148+/-52 and 142+/-43 ng/ml (mean+/-SD) in individuals with and without COPD (Student's t test, p=0.02). Among heterozygotes, corresponding concentrations were 1,665+/-498 ng/ml and 1,256+/-379 (p<0.001). The adjusted odds ratio for spirometrically diagnosed COPD in heterozygotes versus noncarriers was 0.5 (95% confidence interval: 0.3-0.9). After stratification, the equivalent adjusted odds ratio was 1.5 (0.3-6.6) among nonsmokers and 0.4 (0.2-0.8) among smokers (p value for interaction=0.10). The adjusted hazard ratio for COPD hospitalization or death during follow-up in heterozygotes versus noncarriers was 0.3 (0.1-0.8).
  
  
  CONCLUSIONS
  Extracellular superoxide dismutase R213G heterozygosity protects against development of COPD in the Danish general population. This was observed in smokers, but not in nonsmokers.
authors.affiliation: Department of Clinical Biochemistry, Herlev University Hospital, Herlev, Denmark.
authors.forename: Klaus
authors.initials: K
authors.lastname: Juul
authors.forename: Anne
authors.initials: A
authors.lastname: Tybjaerg-Hansen
authors.forename: Stefan
authors.initials: S
authors.lastname: Marklund
authors.forename: Peter
authors.initials: P
authors.lastname: Lange
authors.forename: Børge G
authors.initials: BG
authors.lastname: Nordestgaard
mesh_terms: D000368:Aged; D003430:Cross-Sectional Studies; D004247:DNA / Q000235:genetics*; D003718:Denmark / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D005541:Forced Expiratory Volume; D005819:Genetic Markers; D005838:Genotype; D006801:Humans; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress / Q000235:genetics*; D011110:Polymorphism, Genetic; D011446:Prospective Studies; D029424:Pulmonary Disease, Chronic Obstructive / Q000097:blood / Q000453:epidemiology / Q000235:genetics*; D012720:Severity of Illness Index; D013147:Spirometry; D013482:Superoxide Dismutase / Q000097:blood / Q000235:genetics*; D013997:Time Factors
chemical_list: D005819:Genetic Markers; D004247:DNA; C441642:SOD3 protein, human; D013482:Superoxide Dismutase