title: Increased concordance of severe respiratory syncytial virus infection in identical twins.
abstract: OBJECTIVE
  We estimated differences in the severity of respiratory syncytial virus infection attributable to genetic and environmental factors.
  
  
  METHODS
  Record linkage data on hospitalizations attributable to respiratory syncytial virus infection were gathered on all twins (12,346 pairs) born in Denmark between 1994 and 2003. Latent-factor models of genetic and environmental effects were fitted to the observed data by using maximal likelihood methods.
  
  
  RESULTS
  Identical twins resembled each other significantly more than did fraternal twins for respiratory syncytial virus hospitalization (concordance rate: 0.66 vs 0.53), which suggests genetic influences on disease severity. Genetic factors accounted for 16%, family environment for 73%, and nonshared environment for 11% of the individual susceptibility to develop severe respiratory syncytial virus infection.
  
  
  CONCLUSIONS
  The severity of respiratory syncytial virus infection is determined partly by genetic factors. This result should stimulate the search for genetic markers of disease severity.
authors.affiliation: Department of Respiratory Medicine, Bispebjerg Hospital, Bispebjerg Bakke 23, Building 60 DK-2400 Copenhagen NV, Denmark. sft@city.dk
authors.forename: Simon Francis
authors.initials: SF
authors.lastname: Thomsen
authors.forename: Lone Graff
authors.initials: LG
authors.lastname: Stensballe
authors.forename: Axel
authors.initials: A
authors.lastname: Skytthe
authors.forename: Kirsten Ohm
authors.initials: KO
authors.lastname: Kyvik
authors.forename: Vibeke
authors.initials: V
authors.lastname: Backer
authors.forename: Hans
authors.initials: H
authors.lastname: Bisgaard
mesh_terms: D017677:Age Distribution; D000956:Antigens, Viral / Q000032:analysis; D002675:Child, Preschool; D016001:Confidence Intervals; D003718:Denmark / Q000453:epidemiology; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D005500:Follow-Up Studies; D020022:Genetic Predisposition to Disease / Q000453:epidemiology*; D006801:Humans; D015994:Incidence; D007223:Infant; D008297:Male; D011336:Probability; D016016:Proportional Hazards Models; D012042:Registries; D018357:Respiratory Syncytial Virus Infections / Q000175:diagnosis / Q000453:epidemiology* / Q000235:genetics*; D012189:Retrospective Studies; D012307:Risk Factors; D012720:Severity of Illness Index; D017678:Sex Distribution; D014430:Twins, Monozygotic
chemical_list: D000956:Antigens, Viral