title: Association of genetic variants on 15q12 with cortical thickness and cognition in schizophrenia.
abstract: BACKGROUND
  Cortical thickness is a highly heritable structural brain measurement, and reduced thickness has been associated with schizophrenia, bipolar disorder, and decreased cognitive performance among healthy control individuals. Identifying genes that contribute to variation in cortical thickness provides a means to elucidate some of the biological mechanisms underlying these diseases and general cognitive abilities.
  
  
  OBJECTIVE
  To identify common genetic variants that affect cortical thickness in patients with schizophrenia, patients with bipolar disorder, and controls and to test these variants for association with cognitive performance.
  
  
  METHODS
  A total of 597 198 single-nucleotide polymorphisms were tested for association with average cortical thickness in a genome-wide association study. Significantly associated single-nucleotide polymorphisms were tested for their effect on several measures of cognitive performance.
  
  
  METHODS
  Four major hospitals in Oslo, Norway.
  
  
  METHODS
  A total of 1054 case individuals and controls were analyzed in the genome-wide association study and follow-up cognitive study. The genome-wide association study included controls (n = 181) and individuals with DSM-IV -diagnosed schizophrenia spectrum disorder (n = 94), bipolar spectrum disorder (n = 97), and other psychotic and affective disorders (n = 49).
  
  
  METHODS
  Cortical thickness measured with magnetic resonance imaging and cognitive performance as assessed by several neuropsychological tests.
  
  
  RESULTS
  Two closely linked genetic variants (rs4906844 and rs11633924) within the Prader-Willi and Angelman syndrome region on chromosome 15q12 showed a genome-wide significant association (P = 1.1 x 10(-8) with average cortical thickness and modest association with cognitive performance (permuted P = .03) specifically among patients diagnosed as having schizophrenia.
  
  
  CONCLUSIONS
  This genome-wide association study identifies a common genetic variant that contributes to the heritable reduction of cortical thickness in schizophrenia. These results highlight the usefulness of cortical thickness as an intermediate phenotype for neuropsychiatric diseases. Future independent replication studies are required to confirm these findings.
authors.affiliation: The Scripps Research Institute, Scripps Translational Science Institute, 3344 N Torrey Pines Court, La Jolla, CA 92037, USA. nschork@scripps.edu
authors.forename: Trygve E
authors.initials: TE
authors.lastname: Bakken
authors.forename: Cinnamon S
authors.initials: CS
authors.lastname: Bloss
authors.forename: J Cooper
authors.initials: JC
authors.lastname: Roddey
authors.forename: Alexander H
authors.initials: AH
authors.lastname: Joyner
authors.forename: Lars M
authors.initials: LM
authors.lastname: Rimol
authors.forename: Srdjan
authors.initials: S
authors.lastname: Djurovic
authors.forename: Ingrid
authors.initials: I
authors.lastname: Melle
authors.forename: Kjetil
authors.initials: K
authors.lastname: Sundet
authors.forename: Ingrid
authors.initials: I
authors.lastname: Agartz
authors.forename: Ole A
authors.initials: OA
authors.lastname: Andreassen
authors.forename: Anders M
authors.initials: AM
authors.lastname: Dale
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Schork
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D001284:Atrophy / Q000473:pathology; D001714:Bipolar Disorder / Q000150:complications / Q000235:genetics / Q000473:pathology / Q000523:psychology; D002540:Cerebral Cortex / Q000473:pathology*; D002884:Chromosomes, Human, Pair 15 / Q000235:genetics*; D003072:Cognition Disorders / Q000150:complications / Q000235:genetics* / Q000473:pathology*; D005260:Female; D020022:Genetic Predisposition to Disease / Q000235:genetics; D055106:Genome-Wide Association Study / Q000379:methods; D005838:Genotype; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009483:Neuropsychological Tests; D020641:Polymorphism, Single Nucleotide; D012559:Schizophrenia / Q000150:complications / Q000235:genetics* / Q000473:pathology*; D012565:Schizophrenic Psychology