title: A relationship between migraine and biliary tract disorders: findings in two Swedish samples of elderly twins.
abstract: OBJECTIVE
  To investigate whether there is a relationship between the clinical occurrence of migraine and biliary tract disorders (BTD) and to study whether there is a genetic influence on such an association.
  
  
  METHODS
  The near lifetime morbidity for migraine and BTD was examined in two Swedish twin-samples: OCTO-Twin (149 MZ and 202 DZ pairs; 234 men, 468 women; 80 years of age or older at inclusion), and the GENDER study (249 unlike-sex DZ-pairs; 70-80 years of age at inclusion). The diagnosis of BTD was established by perusal of medical records from the last twenty years. The diagnosis of migraine was based on iterated questionnaires and personal interviews.
  
  
  RESULTS
  The odds ratio (OR) of BTD among OCTO-Twin subjects suffering from migraine was 3.5 (1.9-6.7) in monozygotic pairs and 1.7 (1.0-2.9) in dizygotic pairs The corresponding figures among the GENDER unlike-sex DZ-pairs was 2.7 (1.6-4.5). Migraine was associated with female sex and waist circumference.
  
  
  CONCLUSIONS
  There is a relationship between the occurrence of migraine and BTD, also when controlling for the fact that both disorders are more frequent in women. The association appears to be partly attributable to genetic influences.
authors.affiliation: Institute of Gerontology, Jönköping University, Jönköping, Sweden.
authors.forename: S
authors.initials: S
authors.lastname: Nilsson
authors.forename: L
authors.initials: L
authors.lastname: Edvinsson
authors.forename: B
authors.initials: B
authors.lastname: Malmberg
authors.forename: B
authors.initials: B
authors.lastname: Johansson
authors.forename: M
authors.initials: M
authors.lastname: Linde
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001660:Biliary Tract Diseases / Q000453:epidemiology* / Q000235:genetics; D015897:Comorbidity; D004200:Diseases in Twins / Q000453:epidemiology* / Q000235:genetics; D005260:Female; D006801:Humans; D008297:Male; D008881:Migraine Disorders / Q000453:epidemiology* / Q000235:genetics; D016017:Odds Ratio; D012042:Registries; D012044:Regression Analysis; D012737:Sex Factors; D011795:Surveys and Questionnaires; D014427:Twins / Q000235:genetics*