Association between a novel polymorphism in the promoter region of the neuropeptide Y gene and schizophrenia in humans Masanari Itokawa a,b, * , Makoto Arai a , Shuhei Kato a , Yoko Ogata a,b , Aizo Furukawa c , Seiichi Haga a , Hiroshi Ujike d , Ichiro Sora e , Kazuhiko Ikeda a , Takeo Yoshikawa b a Department of Schizophrenia Research, Tokyo Institute of Psychiatry, 2-1-8 Kamikitazawa, Setagaya, Tokyo 156-8585, Japan b Laboratory for Molecular Psychiatry, RIKEN Brain Science Institute, Saitama 351-0198, Japan c Department of Psychiatry, Tokyo Metropolitan Matsuzawa Hospital, Tokyo 156-0057 Japan d Department of Neuropsychodynamics, Graduate School of Medicine and Dentistry, Okayama University, Okayama 700-8530, Japan e Department of Neuroscience, Division of Psychobiology, Tohoku University Graduate School of Medicine, Sendai 980-8574, Japan Received 16 May 2003; received in revised form 9 June 2003; accepted 12 June 2003 Abstract Hypoactivity of neuropeptide Y (NPY) is thought to be involved in the pathophysiology of schizophrenia, because post-mortem brain studies revealed a decrease of the NPY in schizophrenia, and antipsychotic treatments increase the NPY in animal brains and in cerebrospinal fluid of patients. We performed genetic analysis of the NPY gene in schizophrenia. Mutation screening of the gene detected nine single nucleotide polymorphisms, of which we typed a 2 485C . T variation from potential functional relevance. The 2 485T allele was overly represented in the disease group (P ¼ 0:0043). An in vitro promoter assay revealed that a C to T change at nt 2 485 significantly reduced transcriptional activity. These results suggest that the 2 485T allele in NPY may confer susceptibility to schizophrenia by decreasing the neuropeptide in brains. q 2003 Elsevier Science Ireland Ltd. All rights reserved. Keywords: Case-control study; 2 485C . T polymorphism; Luciferase activity; IMR-32 cell; 1128T . C (Leu7Pro) polymorphism; Japanese Schizophrenia is a relatively common and devastating mental illness characterized by hallucinations, delusions, affective flattening, and alogia [8]. Family and twin studies have shown the importance of genetic factors in the etiology of schizophrenia [5]. Several lines of evidence have supported the idea that hypoactivity of neuropeptide Y (NPY)-containing neurons in the brain plays a role in the pathophysiology of schizo- phrenia. NPY content was reduced in the post-mortem brains of schizophrenics [3,4]. Electroconvulsive treatment is known to elevate the NPY concentration in the cerebrospinal fluid of schizophrenic patients [14]. Chronic administration of neuroleptics increased the NPY level in the cerebral cortex of rats [15]. Kuromitsu et al. [10] recently reported by using DNA microarray technology that the NPY mRNA levels were significantly reduced in the frontal cortices of schizophrenics compared with those of matched controls. These pieces of evidence make the NPY gene a compelling candidate for susceptibility to schizophrenia. For case-control association analysis, we recruited 212 unrelated schizophrenics, of whom 112 subjects were males (mean age 52.2 ^ 10.4) and 100 were females (mean age 53.9 ^ 12.9). The diagnosis of schizophrenia was made according to the Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition (DSM-IV) (American Psychiatric Association), and on the consensus of at least two experienced psychiatrists. Mentally healthy control subjects included 100 males (mean age 56.8 ^ 18.7) and 99 females (mean age 53.8 ^ 14.7). All the samples were derived from central Japan. The present study was approved by the Ethics Committees of both Okayama University and Tokyo Institute of Psychiatry, with all participants giving informed consent. All the exons, splice boundaries and 5 0 upstream region (up to 2 620 bp from A of the initiation codon ATG) of the NPY gene were screened for polymorphisms by direct sequencing of PCR products, using 20 unrelated schizo- phrenia samples. The information on primer sequences and amplification conditions is available upon request. The Neuroscience Letters 347 (2003) 202–204 www.elsevier.com/locate/neulet 0304-3940/03/$ - see front matter q 2003 Elsevier Science Ireland Ltd. All rights reserved. doi:10.1016/S0304-3940(03)00718-3 * Corresponding author. Department of Schizophrenia Research, Tokyo Institute of Psychiatry, 2-1-8 Kamikitazawa, Setagaya, Tokyo 156-8585, Japan. Tel.: þ 81-3-3304-5701; fax: þ81-3-3329-8035. E-mail address: mitokawa@prit.go.jp (M. Itokawa).