title: GAD1 Gene Expression in Blood of Patients with First-Episode Psychosis.
abstract: γ-Aminobutyric acid (GABA), the primary inhibitory neurotransmitter, has often been studied in relation to its role in the pathophysiology of schizophrenia. GABA is synthesized from glutamate by glutamic acid decarboxylase (GAD), derived from two genes, GAD1 and GAD2. GAD1 is expressed as both GAD67 and GAD25 mRNA transcripts with the former reported to have a lower expression level in schizophrenia compared to healthy controls and latter was reported to be predominantly expressed fetally, suggesting a role in developmental process. In this study, GAD67 and GAD25 mRNA levels were measured by quantitative PCR (qPCR) in peripheral blood of subjects with first-episode psychosis (FEP) and from healthy controls. We observed low GAD25 and GAD67 gene expression levels in human peripheral blood. There was no difference in GAD25 and GAD67 gene expression level, and GAD25/GAD67 ratio between patients with FEP and healthy controls. PANSS negative symptoms were associated with levels of GAD25 mRNA transcripts in patients with FEP. While the current study provides information on GAD25 and GAD67 mRNA transcript levels in whole blood of FEP patients, further correlation and validation work between brain regions, cerebrospinal fluid and peripheral blood expression profiling are required to provide a better understanding of GAD25 and GAD67.
authors.affiliation: Research Division, Institute of Mental Health, Singapore, Singapore.
authors.forename: Jie Yin
authors.initials: JY
authors.lastname: Yee
authors.affiliation: Saw Swee Hock School of Public Health, National University of Singapore, Singapore, Singapore.
authors.forename: Milawaty
authors.initials: M
authors.lastname: Nurjono
authors.affiliation: Neuroscience & Behavioural Disorders, Duke-NUS Medical School, Singapore, Singapore.
authors.forename: Stephanie Ruth
authors.initials: SR
authors.lastname: Teo
authors.affiliation: Neuroscience & Behavioural Disorders, Duke-NUS Medical School, Singapore, Singapore.
authors.forename: Tih-Shih
authors.initials: TS
authors.lastname: Lee
authors.affiliation: Research Division, Institute of Mental Health, Singapore, Singapore.|Department of General Psychiatry 1, Institute of Mental Health, Singapore, Singapore.
authors.forename: Jimmy
authors.initials: J
authors.lastname: Lee
mesh_terms: D000328:Adult; D005260:Female; D015870:Gene Expression; D005968:Glutamate Decarboxylase / Q000235:genetics*; D006801:Humans; D008297:Male; D011618:Psychotic Disorders / Q000175:diagnosis / Q000235:genetics*; D055815:Young Adult
chemical_list: D005968:Glutamate Decarboxylase; C402565:glutamate decarboxylase 1