title: Genetic influences in gastro-oesophageal reflux disease: a twin study.
abstract: BACKGROUND
  A number of families have been described which include multiple members with symptomatic, endoscopic, or complicated gastro-oesophageal reflux disease (GORD). First degree relatives of patients with GORD are more likely to suffer with GORD symptoms. These observations raise the possibility of a genetic contribution to the aetiology of GORD.
  
  
  OBJECTIVE
  To determine the relative contribution of genetic factors to GORD by evaluating GORD symptoms in monozygotic (MZ) and dizygotic (DZ) twins.
  
  
  METHODS
  A total of 4480 unselected twin pairs, identified from a national volunteer twin register, were asked to complete a validated symptom questionnaire. GORD was defined as symptoms of heartburn or acid regurgitation at least weekly during the past year.
  
  
  RESULTS
  Replies were obtained from 5032 subjects (56% response rate). A total of 1960 twin pairs were evaluable: 928 MZ pairs (86 male pairs, mean (SD) age 52 (13) (range 19-81) years) and 1032 DZ pairs (71 male pairs, mean age 52 (13) (20-82) years). The prevalence of GORD among both groups of twins was 18%. Casewise concordance rates were significantly higher for MZ than DZ twins (42% v 26%; p<0.001). Multifactorial liability threshold modelling suggests that additive genetic effects combined with unique environmental factors provide the best model for GORD. Heritability estimates suggest that 43% (95% confidence interval 32-55%) of the variance in liability to GORD is due to additive genetic factors.
  
  
  CONCLUSIONS
  There is a substantial genetic contribution to the aetiology of GORD.
authors.affiliation: Department of Gastroenterology, Sandwell General Hospital, West Bromich, UK.
authors.forename: I
authors.initials: I
authors.lastname: Mohammed
authors.forename: L F
authors.initials: LF
authors.lastname: Cherkas
authors.forename: S A
authors.initials: SA
authors.lastname: Riley
authors.forename: T D
authors.initials: TD
authors.lastname: Spector
authors.forename: N J
authors.initials: NJ
authors.lastname: Trudgill
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D005260:Female; D005764:Gastroesophageal Reflux / Q000235:genetics*; D006801:Humans; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D010641:Phenotype; D012044:Regression Analysis