title: Bronchial hyperresponsiveness in adolescents with long-term asthma remission: importance of a Family history of bronchial hyperresponsiveness.
abstract: BACKGROUND
  The mechanisms responsible for bronchial hyperresponsiveness (BHR) in symptomatic asthma include genetic predisposition and airway inflammation, but the causes of BHR in adolescents with asthma remission are poorly understood. It has been shown that BHR in adolescents with asthma remission was not reduced by prolonged treatment with inhaled corticosteroids, in contrast to the BHR of symptomatic asthma.
  
  
  OBJECTIVE
  The aim of this study was to investigate whether family history of BHR may contribute to the persistence of BHR in asthma remission during adolescence.
  
  
  METHODS
  One hundred twenty-six adolescents with long-term asthma remission (neither symptoms nor any medication used during the previous 2 years) and their parents underwent a methacholine inhalation test. The provocative concentration of methacholine causing a 20% fall in FEV(1) (PC(20)) and the bronchial responsiveness (BR) index were calculated for each individual.
  
  
  RESULTS
  Sixty-nine adolescents (54.8%) were found to have persisting BHR (PC(20) < 18 mg/mL). The frequency of BHR and the BR index were significantly higher in parents (n = 138) of the BHR-persisting group (28.3% and 1.150 +/- 0.103, respectively [mean +/- 1 SD]) than in parents (n = 114) of BHR-nonpersisting group (16.7% [p = 0.030] and 1.124 +/- 0.088 [p = 0.029], respectively). Furthermore, adolescents (n = 56) with at least one BHR-positive parent were found to have a higher frequency of BHR (66.1% vs 45.7%, p = 0.023) and a higher BR index (1.244 +/- 0.090 vs 1.204 +/- 0.082, p = 0.011) than adolescents (n = 70) with non-BHR parents.
  
  
  CONCLUSIONS
  Our results suggest that adolescents in asthma remission are more likely to have BHR when there is a family history of BHR. Further studies are needed to examine the possible involvement of genetic factors in the BHR of adolescents in asthma remission.
authors.affiliation: Department of Pediatrics and Clinical Research Institute, Seoul National University Hospital, 28 Yongon-dong, Chongno-gu, Seoul 110-744, Korea. kohyy@plaza.snu.ac.kr
authors.forename: Young Yull
authors.initials: YY
authors.lastname: Koh
authors.forename: Eun Kyeong
authors.initials: EK
authors.lastname: Kang
authors.forename: Hee
authors.initials: H
authors.lastname: Kang
authors.forename: Young
authors.initials: Y
authors.lastname: Yoo
authors.forename: Yang
authors.initials: Y
authors.lastname: Park
authors.forename: Chang Keun
authors.initials: CK
authors.lastname: Kim
mesh_terms: D000293:Adolescent; D018927:Anti-Asthmatic Agents / Q000627:therapeutic use; D001249:Asthma / Q000188:drug therapy / Q000235:genetics* / Q000503:physiopathology; D016535:Bronchial Hyperreactivity / Q000188:drug therapy / Q000235:genetics* / Q000503:physiopathology; D001985:Bronchial Provocation Tests; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D006801:Humans; D008297:Male; D016210:Methacholine Chloride; D012074:Remission Induction; D012307:Risk Factors
chemical_list: D018927:Anti-Asthmatic Agents; D016210:Methacholine Chloride