title: Gene expression-based biological test for major depressive disorder: an advanced study.
abstract: OBJECTIVE
  Recently, we could distinguished patients with major depressive disorder (MDD) from nonpsychiatric controls with high accuracy using a panel of five gene expression markers (ARHGAP24, HDAC5, PDGFC, PRNP, andSLC6A4) in leukocyte. In the present study, we examined whether this biological test is able to discriminate patients with MDD from those without MDD, including those with schizophrenia and bipolar disorder.
  
  
  METHODS
  We measured messenger ribonucleic acid expression levels of the aforementioned five genes in peripheral leukocytes in 17 patients with schizophrenia and 36 patients with bipolar disorder using quantitative real-time polymerase chain reaction (PCR), and we combined these expression data with our previous expression data of 25 patients with MDD and 25 controls. Subsequently, a linear discriminant function was developed for use in discriminating between patients with MDD and without MDD.
  
  
  RESULTS
  This expression panel was able to segregate patients with MDD from those without MDD with a sensitivity and specificity of 64% and 67.9%, respectively.
  
  
  CONCLUSIONS
  Further research to identify MDD-specific markers is needed to improve the performance of this biological test.
authors.affiliation: Department of Psychiatry, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima.
authors.forename: Shin-Ya
authors.initials: SY
authors.lastname: Watanabe
authors.affiliation: Department of Psychiatry, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima.
authors.forename: Shusuke
authors.initials: S
authors.lastname: Numata
authors.affiliation: Department of Neuropsychiatry, Molecules and Function, Ehime University Graduate School of Medicine, Ehime.
authors.forename: Jun-Ichi
authors.initials: JI
authors.lastname: Iga
authors.affiliation: Department of Psychiatry, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima.
authors.forename: Makoto
authors.initials: M
authors.lastname: Kinoshita
authors.affiliation: Department of Psychiatry, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima.
authors.forename: Hidehiro
authors.initials: H
authors.lastname: Umehara
authors.affiliation: Department of Applied Biological Science, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo, Japan.
authors.forename: Kazuo
authors.initials: K
authors.lastname: Ishii
authors.affiliation: Department of Psychiatry, Institute of Biomedical Sciences, Tokushima University Graduate School, Tokushima.
authors.forename: Tetsuro
authors.initials: T
authors.lastname: Ohmori
keywords: biomarker; bipolar disorder; depressive disorder; gene expression; schizophrenia