title: Cortical GABA markers identify a molecular subtype of psychotic and bipolar disorders.
abstract: Deficits in gamma aminobutyric acid (GABA) neuron-related markers, including the GABA-synthesizing enzyme GAD67, the calcium-binding protein parvalbumin, the neuropeptide somatostatin, and the transcription factor Lhx6, are most pronounced in a subset of schizophrenia subjects identified as having a 'low GABA marker' (LGM) molecular phenotype. Furthermore, schizophrenia shares degrees of genetic liability, clinical features and cortical circuitry abnormalities with schizoaffective disorder and bipolar disorder. Therefore, we determined the extent to which a similar LGM molecular phenotype may also exist in subjects with these disorders.
  
  
  
  Transcript levels for GAD67, parvalbumin, somatostatin, and Lhx6 were quantified using quantitative PCR in prefrontal cortex area 9 of 184 subjects with a diagnosis of schizophrenia (n = 39), schizoaffective disorder (n = 23) or bipolar disorder (n = 35), or with a confirmed absence of any psychiatric diagnoses (n = 87). A blinded clustering approach was employed to determine the presence of a LGM molecular phenotype across all subjects.
  
  
  
  Approximately 49% of the subjects with schizophrenia, 48% of the subjects with schizoaffective disorder, and 29% of the subjects with bipolar disorder, but only 5% of unaffected subjects, clustered in the cortical LGM molecular phenotype.
  
  
  
  These findings support the characterization of psychotic and bipolar disorders by cortical molecular phenotype which may help elucidate more pathophysiologically informed and personalized medications.
authors.affiliation: Department of Psychiatry,University of Pittsburgh,Pittsburgh, PA,USA.
authors.forename: D W
authors.initials: DW
authors.lastname: Volk
authors.affiliation: Department of Statistics,University of Pittsburgh,Pittsburgh, PA,USA.
authors.forename: A R
authors.initials: AR
authors.lastname: Sampson
authors.affiliation: Department of Statistics,University of Pittsburgh,Pittsburgh, PA,USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Zhang
authors.affiliation: Department of Psychiatry,University of Pittsburgh,Pittsburgh, PA,USA.
authors.forename: J R
authors.initials: JR
authors.lastname: Edelson
authors.affiliation: Department of Psychiatry,University of Pittsburgh,Pittsburgh, PA,USA.
authors.forename: D A
authors.initials: DA
authors.lastname: Lewis
mesh_terms: D000328:Adult; D015415:Biomarkers / Q000378:metabolism; D001714:Bipolar Disorder / Q000378:metabolism*; D005260:Female; D059330:GABAergic Neurons / Q000378:metabolism*; D005968:Glutamate Decarboxylase / Q000378:metabolism; D006801:Humans; D060850:LIM-Homeodomain Proteins / Q000378:metabolism; D008297:Male; D008875:Middle Aged; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010320:Parvalbumins / Q000378:metabolism; D010641:Phenotype; D017397:Prefrontal Cortex / Q000378:metabolism*; D011618:Psychotic Disorders / Q000378:metabolism*; D012559:Schizophrenia / Q000378:metabolism*; D013004:Somatostatin / Q000378:metabolism; D014157:Transcription Factors / Q000378:metabolism; D005680:gamma-Aminobutyric Acid / Q000378:metabolism*
chemical_list: D015415:Biomarkers; C121947:LHX6 protein, human; D060850:LIM-Homeodomain Proteins; D009419:Nerve Tissue Proteins; D010320:Parvalbumins; D014157:Transcription Factors; D013004:Somatostatin; D005680:gamma-Aminobutyric Acid; D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1
keywords: Inhibitory; postmortem; prefrontal cortex; schizoaffective; schizophrenia