title: A common genetic factor underlies hypertension and other cardiovascular disorders.
abstract: BACKGROUND
  Certain conditions characterised by blood vessel occlusion or vascular spasm have been found to cluster together in epidemiological studies. However the biological causes for these associations remain controversial. This study used a classical twin design to examine whether these conditions are linked through shared environmental exposures or by a common underlying genetic propensity to vasospasm.
  
  
  METHODS
  We investigated the association between hypertension, migraine, Raynaud's phenomenon and coronary artery disease in twins from a national register. Phenotype status was determined using a questionnaire and the genetic and environmental association between phenotypes was estimated through variance components analysis.
  
  
  RESULTS
  Responses were obtained from 2,204 individuals comprising 525 monozygotic and 577 dizygotic pairs. There was a significant genetic contribution to all four traits with heritabilities ranging from 0.34 to 0.64. Multivariate model-fitting demonstrated that a single common genetic factor underlies the four conditions.
  
  
  CONCLUSIONS
  We have confirmed an association between hypertension, migraine, Raynaud's phenomenon and coronary artery disease, and shown that a single genetic factor underlies them. The demonstration of a shared genetic factor explains the association between them and adds weight to the theory of an inherited predisposition to vasospasm.
authors.affiliation: Twin Research and Genetic Epidemiology Unit, St Thomas' Hospital, London SE1 7EH, UK. frances.williams@gstt.nhs.uk
authors.forename: Frances M K
authors.initials: FM
authors.lastname: Williams
authors.forename: Lynn F
authors.initials: LF
authors.lastname: Cherkas
authors.forename: Tim D
authors.initials: TD
authors.lastname: Spector
authors.forename: Alex J
authors.initials: AJ
authors.lastname: MacGregor
mesh_terms: D000293:Adolescent; D000328:Adult; D002318:Cardiovascular Diseases / Q000235:genetics*; D003324:Coronary Artery Disease / Q000235:genetics; D004200:Diseases in Twins / Q000235:genetics; D004777:Environment; D005260:Female; D020022:Genetic Predisposition to Disease; D006801:Humans; D006973:Hypertension / Q000235:genetics*; D008875:Middle Aged; D008881:Migraine Disorders / Q000235:genetics; D010641:Phenotype; D011928:Raynaud Disease / Q000235:genetics; D012307:Risk Factors; D014429:Twins, Dizygotic / Q000235:genetics; D014430:Twins, Monozygotic / Q000235:genetics