title: The genetic and environmental determinants of the association between brain abnormalities and schizophrenia: the schizophrenia twins and relatives consortium.
abstract: BACKGROUND
  Structural brain abnormalities are consistently found in schizophrenia (Sz) and have been associated with the familial risk for the disorder. We aim to define the relative contributions of genetic and nongenetic factors to the association between structural brain abnormalities and Sz in a uniquely powered cohort (Schizophrenia Twins and Relatives consortium).
  
  
  METHODS
  An international multicenter magnetic resonance imaging collaboration was set up to pool magnetic resonance imaging scans from twin pairs in Utrecht (The Netherlands), Helsinki (Finland), London (United Kingdom), and Jena (Germany). A sample of 684 subjects took part, consisting of monozygotic twins (n = 410, with 51 patients from concordant and 52 from discordant pairs) and dizygotic twins (n = 274, with 39 patients from discordant pairs). The additive genetic, common, and unique environmental contributions to the association between brain volumes and risk for Sz were estimated by structural equation modeling.
  
  
  RESULTS
  The heritabilities of most brain volumes were significant and ranged between 52% (temporal cortical gray matter) and 76% (cerebrum). Heritability of cerebral gray matter did not reach significance (34%). Significant phenotypic correlations were found between Sz and reduced volumes of the cerebrum (-.22 [-.30/-.14]) and white matter (-.17 [-.25/-.09]) and increased volume of the third ventricle (.18 [.08/.28]). These were predominantly due to overlapping genetic effects (77%, 94%, and 83%, respectively).
  
  
  CONCLUSIONS
  Some of the genes that transmit the risk for Sz also influence cerebral (white matter) volume.
authors.affiliation: University Medical Center Utrecht, Department of Psychiatry, Division of Neuroscience, Rudolf Magnus Institute, Utrecht, The Netherlands. n.e.m.vanharen@umcutrecht.nl
authors.forename: Neeltje E M
authors.initials: NE
authors.lastname: van Haren
authors.forename: Fruhling
authors.initials: F
authors.lastname: Rijsdijk
authors.forename: Hugo G
authors.initials: HG
authors.lastname: Schnack
authors.forename: Marco M
authors.initials: MM
authors.lastname: Picchioni
authors.forename: Timothea
authors.initials: T
authors.lastname: Toulopoulou
authors.forename: Matthias
authors.initials: M
authors.lastname: Weisbrod
authors.forename: Heinrich
authors.initials: H
authors.lastname: Sauer
authors.forename: Theo G
authors.initials: TG
authors.lastname: van Erp
authors.forename: Tyrone D
authors.initials: TD
authors.lastname: Cannon
authors.forename: Matti O
authors.initials: MO
authors.lastname: Huttunen
authors.forename: Dorret I
authors.initials: DI
authors.lastname: Boomsma
authors.forename: Hilleke E
authors.initials: HE
authors.lastname: Hulshoff Pol
authors.forename: Robin M
authors.initials: RM
authors.lastname: Murray
authors.forename: Rene S
authors.initials: RS
authors.lastname: Kahn
mesh_terms: D000328:Adult; D001921:Brain / Q000473:pathology*; D004200:Diseases in Twins / Q000235:genetics* / Q000473:pathology; D005260:Female; D059647:Gene-Environment Interaction; D020022:Genetic Predisposition to Disease; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009929:Organ Size; D012559:Schizophrenia / Q000235:genetics* / Q000473:pathology*; D014429:Twins, Dizygotic / Q000523:psychology*; D014430:Twins, Monozygotic / Q000523:psychology*