title: The genetic influence on diverticular disease--a twin study.
abstract: BACKGROUND
  The contribution of hereditary factors to the development of diverticular disease (DD) of the colon is unknown. Prevalence and location of diverticula differ in Western world compared to in Asia and several case reports describing families with DD have been published.
  
  
  OBJECTIVE
  To assess the heritability of DD in a large population-based sample of twins.
  
  
  METHODS
  The Swedish Twin Registry was cross-linked to the Swedish Inpatient Registry. All twins, born between 1886 and 1980 and not dead before 1969, with a discharge diagnosis of DD were identified. Twins with diagnoses of colon cancer, coeliac disease or non-infectious colitis were excluded to decrease bias. Co-twin odds ratio (OR), concordance rates and tetrachoric correlations were calculated for monozygotic (MZ) and same gender-dizygotic (SS-DZ) twins. Mx-analyses were used to estimate the relative contributions of genetic effects and environmental factors to susceptibility for DD. Calculations were based on both primary and secondary discharge diagnoses to provide estimates reflecting impact of severity of the disease.
  
  
  RESULTS
  A total of 104,452 twins met the inclusion criteria. Of these, 2296 had a diagnosis of DD. The OR of developing the disease given one's co-twin was affected was 7.15 (95% CI: 4.82-10.61) for MZ and 3.20 (95% CI: 2.21-4.63) for SS-DZ twins. Similarly, concordance rates and tetrachoric correlations were higher in MZ than those in SS-DZ twins. The heritability was estimated to 40% and the non shared environmental effects to 60%.
  
  
  CONCLUSIONS
  Genetic susceptibility is an important component, along with individual specific environmental factors, for the development of diverticular disease of the colon.
authors.affiliation: Unit of Gastroenterology and Hepatology, Department of Medicine, Solna, Karolinska Institutet, Karolinska University Hospital, Stockholm, Sweden.
authors.forename: J
authors.initials: J
authors.lastname: Granlund
authors.forename: T
authors.initials: T
authors.lastname: Svensson
authors.forename: O
authors.initials: O
authors.lastname: Olén
authors.forename: F
authors.initials: F
authors.lastname: Hjern
authors.forename: N L
authors.initials: NL
authors.lastname: Pedersen
authors.forename: P K E
authors.initials: PK
authors.lastname: Magnusson
authors.forename: P Thelin
authors.initials: PT
authors.lastname: Schmidt
mesh_terms: D000368:Aged; D004240:Diverticulum / Q000453:epidemiology / Q000235:genetics*; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D015995:Prevalence; D012042:Registries; D012720:Severity of Illness Index; D013548:Sweden / Q000453:epidemiology; D014429:Twins, Dizygotic / Q000235:genetics*; D014430:Twins, Monozygotic / Q000235:genetics*