title: Association analysis of the Cadherin13 gene with schizophrenia in the Japanese population.
abstract: BACKGROUND
  Cadherin13 (CDH13) is a glycosylphosphatidylinositol-anchored cell adhesion molecule that plays a crucial role in morphogenesis and the maintenance of neuronal circuitry. CDH13 has been implicated in the susceptibility to a variety of psychiatric diseases. A recent genome-wide association study using Danish samples showed, for the first time, the involvement of a single nucleotide polymorphism (SNP) of CDH13 (intronic SNP rs8057927) in schizophrenia. Here, we investigated the association between other SNPs of CDH13 and schizophrenia and tried to replicate the association for the SNP of rs8057927, in the Japanese population.
  
  
  METHODS
  Using TaqMan(®) SNP genotyping assays, five tag SNPs (rs12925602, rs7193788, rs736719, rs6565051, and rs7204454) in the promoter region of CDH13 were examined for their association with schizophrenia in two independent samples. The first sample comprised 665 patients and 760 controls, and the second sample comprised 677 patients and 667 controls. One tag SNP for rs8057927 was also examined for the association with schizophrenia in the first sample set.
  
  
  RESULTS
  A GACAG haplotype of the five SNPs in the promoter region of CDH13 was significantly associated with schizophrenia in the first sample set (P=0.016 and corrected P=0.098). A combined analysis of the GACAG haplotype with the second sample set enhanced the significance (P=0.0026 and corrected P=0.021). We found no association between rs8057927 and schizophrenia in the first sample set.
  
  
  CONCLUSIONS
  Our results suggest that CDH13 may contribute to the genetic risk of schizophrenia. Further replication on the association of CDH13 with schizophrenia and functional studies are required to confirm the current findings.
authors.affiliation: Department of Psychiatry, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Ikuo
authors.initials: I
authors.lastname: Otsuka
authors.affiliation: Department of Psychiatry, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Watanabe
authors.affiliation: Department of Psychiatry, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Akitoyo
authors.initials: A
authors.lastname: Hishimoto
authors.affiliation: Department of Psychiatry, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Shuken
authors.initials: S
authors.lastname: Boku
authors.affiliation: Department of Psychiatry, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Kentaro
authors.initials: K
authors.lastname: Mouri
authors.affiliation: Department of Psychiatry, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Shiroiwa
authors.affiliation: Department of Psychiatry, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Okazaki
authors.affiliation: Department of Psychiatry, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Ayako
authors.initials: A
authors.lastname: Nunokawa
authors.affiliation: Department of Neuropsychiatry, School of Medicine, Kinki University, Osaka, Japan.
authors.forename: Osamu
authors.initials: O
authors.lastname: Shirakawa
authors.affiliation: Department of Psychiatry, Graduate School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
authors.forename: Toshiyuki
authors.initials: T
authors.lastname: Someya
authors.affiliation: Department of Psychiatry, Graduate School of Medicine, Kobe University, Kobe, Japan.
authors.forename: Ichiro
authors.initials: I
authors.lastname: Sora
keywords: CDH13; SNP; haplotype; promoter region