title: Endophenotypes in schizophrenia: a selective review.
abstract: BACKGROUND
  Given the wealth of data in the literature on schizophrenia endophenotypes, it is useful to have one source to reference their frequency data. We reviewed the literature on disease-liability associated variants in structural and functional magnetic resonance images (MRI), sensory processing measures, neuromotor abilities, neuropsychological measures, and physical characteristics in schizophrenia patients (SCZ), their first-degree relatives (REL), and healthy controls (HC). The purpose of this review was to provide a summary of the existing data on the most extensively published endophenotypes for schizophrenia.
  
  
  METHODS
  We searched PubMed and MedLine for all studies on schizophrenia endophenotypes comparing SCZ to HC and/or REL to HC groups. Percent abnormal values, generally defined as >2 SD from the mean (in the direction of abnormality) and/or associated effect sizes (Cohen's d) were calculated for each study.
  
  
  RESULTS
  Combined, the articles reported an average 39.4% (SD=20.7%; range=2.2-100%) of abnormal values in SCZ, 28.1% (SD=16.6%; range=1.6-67.0%) abnormal values in REL, and 10.2% (SD=6.7%; range=0.0-34.6%) in HC groups.
  
  
  CONCLUSIONS
  These findings are reviewed in the context of emerging hypotheses on schizophrenia endophenotypes, as well as a discussion of clustering trends among the various intermediate phenotypes. In addition, programs for future research are discussed, as instantiated in a few recent large-scale studies on multiple endophenotypes across patients, relatives, and healthy controls.
authors.affiliation: Olin Neuropsychiatry Research Center, Institute of Living at Hartford Hospital, 200 Retreat Avenue, Hartford, CT 06106, United States. allyssaallen@hotmail.com
authors.forename: Allyssa J
authors.initials: AJ
authors.lastname: Allen
authors.forename: Mélina E
authors.initials: ME
authors.lastname: Griss
authors.forename: Bradley S
authors.initials: BS
authors.lastname: Folley
authors.forename: Keith A
authors.initials: KA
authors.lastname: Hawkins
authors.forename: Godfrey D
authors.initials: GD
authors.lastname: Pearlson
mesh_terms: D015415:Biomarkers; D016000:Cluster Analysis; D003072:Cognition Disorders / Q000175:diagnosis / Q000235:genetics / Q000523:psychology; D005190:Family; D006801:Humans; D010641:Phenotype; D012559:Schizophrenia / Q000175:diagnosis / Q000235:genetics*; D012565:Schizophrenic Psychology; D013223:Statistics as Topic
chemical_list: D015415:Biomarkers