title: The genetics of symptom dimensions of schizophrenia: review and meta-analysis.
abstract: BACKGROUND
  The use of symptom dimensions of schizophrenia as quantitative phenotypes has been proposed as a mean to reduce the heterogeneity of schizophrenia and facilitate genetic research. However, the genetic background of symptom dimensions is not clear.
  
  
  OBJECTIVE
  We aim to investigate whether the symptom dimensions "reality distortion", "psychomotor poverty" and "disorganization" are heritable phenotypes.
  
  
  METHODS
  We performed a Medline search including all papers from 1980 to August 2007. In addition to reviewing the articles, we performed meta-analyses on these studies where possible.
  
  
  RESULTS
  We identified 18 relevant papers. Only the studies on affected sibling pairs were suitable for meta-analysis. Data from twin and affected sibling studies are consistent with a genetic contribution to the disorganization dimension. However these studies did not unequivocally support a large genetic contribution to neither the reality distortion symptom dimension nor to the psychomotor poverty symptom dimension. In contrast several molecular genetic studies did report associations of genes with psychomotor poverty.
  
  
  CONCLUSIONS
  These data suggest that only the disorganization symptom dimension may provide an useful alternative phenotype for genetic research. More research is required to make any definitive conclusions.
authors.affiliation: Rudolf Magnus Institute of Neuroscience, Department of Psychiatry, B01.206, University Medical Centre Utrecht, PO Box 85500, 3508 GA Utrecht, The Netherlands. T.Rietkerk@umcutrecht.nl
authors.forename: T
authors.initials: T
authors.lastname: Rietkerk
authors.forename: M P M
authors.initials: MP
authors.lastname: Boks
authors.forename: I E
authors.initials: IE
authors.lastname: Sommer
authors.forename: P F
authors.initials: PF
authors.lastname: Liddle
authors.forename: R A
authors.initials: RA
authors.lastname: Ophoff
authors.forename: R S
authors.initials: RS
authors.lastname: Kahn
mesh_terms: D004200:Diseases in Twins / Q000175:diagnosis / Q000235:genetics; D005190:Family; D018740:Genetic Heterogeneity; D005838:Genotype; D006801:Humans; D015810:Linkage Disequilibrium; D010375:Pedigree; D010641:Phenotype; D011596:Psychomotor Disorders / Q000175:diagnosis / Q000235:genetics; D011936:Reality Testing; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics*; D012562:Schizophrenia, Disorganized / Q000235:genetics; D012565:Schizophrenic Psychology