title: Heritability of respiratory infection with Pseudomonas aeruginosa in cystic fibrosis.
abstract: OBJECTIVE
  To quantify the relative contribution of factors other than cystic fibrosis transmembrane conductance regulator genotype and environment on the acquisition of Pseudomonas aeruginosa (Pa) by patients with cystic fibrosis.
  
  
  METHODS
  Lung infection with Pa and mucoid Pa was assessed using a co-twin study design of 44 monozygous (MZ) and 17 dizygous (DZ) twin pairs. Two definitions were used to establish infection: first positive culture and persistent positive culture. Genetic contribution to infection (ie, heritability) was estimated based on concordance analysis, logistic regression, and age at onset of infection through comparison of intraclass correlation coefficients.
  
  
  RESULTS
  Concordance for persistent Pa infection was higher in MZ (0.83; 25 of 30 pairs) than DZ twins (0.45; 5 of 11 pairs), generating a heritability of 0.76. Logistic regression adjusted for age corroborated genetic control of persistent Pa infection. The correlation for age at persistent Pa infection was higher in MZ twins (0.589; 95% CI, 0.222-0.704) than in DZ twins (0.162; 95% CI, -0.352 to 0.607), generating a heritability of 0.85.
  
  
  CONCLUSIONS
  Genetic modifiers play a significant role in the establishment and timing of persistent Pa infection in individuals with cystic fibrosis.
authors.affiliation: Division of Pediatric Pulmonary and Sleep Medicine, Duke University Medical Center, Durham, NC, USA.
authors.forename: Deanna M
authors.initials: DM
authors.lastname: Green
authors.forename: J Michael
authors.initials: JM
authors.lastname: Collaco
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: McDougal
authors.forename: Kathleen M
authors.initials: KM
authors.lastname: Naughton
authors.forename: Scott M
authors.initials: SM
authors.lastname: Blackman
authors.forename: Garry R
authors.initials: GR
authors.lastname: Cutting
mesh_terms: D000293:Adolescent; D002648:Child; D002675:Child, Preschool; D003550:Cystic Fibrosis / Q000235:genetics* / Q000382:microbiology; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000235:genetics; D004200:Diseases in Twins / Q000235:genetics*; D004843:Epistasis, Genetic; D005260:Female; D060045:Genes, Modifier / Q000235:genetics*; D006801:Humans; D008297:Male; D011552:Pseudomonas Infections / Q000150:complications / Q000235:genetics*; D011550:Pseudomonas aeruginosa; D012141:Respiratory Tract Infections / Q000150:complications / Q000235:genetics*; D014429:Twins, Dizygotic; D014430:Twins, Monozygotic
chemical_list: D019005:Cystic Fibrosis Transmembrane Conductance Regulator