title: Human leukocyte antigen and season of birth in Japanese patients with schizophrenia.
abstract: OBJECTIVE
  Five Japanese studies, to the authors' knowledge, without exception, have consistently shown an increased frequency of human leukocyte antigen (HLA)-DR1 in patients with schizophrenia. This suggests an association between HLA-DR1 and schizophrenia in the Japanese population. The mechanism of the association is unknown; however, prenatal infections may be involved. The present study explored factors, including winter birth, that might correlate with this mechanism. Age at onset and gender were also studied.
  
  
  METHODS
  Factors were compared between Japanese patients with schizophrenia with and in those without HLA-DR1 (N=60 and N=307, respectively).
  
  
  RESULTS
  A significantly higher incidence of births in February and March was observed in patients with (31.7%) than those without (15. 6%) HLA-DR1. No association was found between the presence of HLA-DR1 and other variables.
  
  
  CONCLUSIONS
  Although this result is preliminary, it may suggest an interaction between HLA and winter birth in the development of schizophrenia in the Japanese population.
authors.affiliation: Department of Psychiatry, Mizonokuchi Hospital, Teikyo University, Kawasaki, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Narita
authors.forename: T
authors.initials: T
authors.lastname: Sasaki
authors.forename: R
authors.initials: R
authors.lastname: Akaho
authors.forename: Y
authors.initials: Y
authors.lastname: Okazaki
authors.forename: I
authors.initials: I
authors.lastname: Kusumi
authors.forename: T
authors.initials: T
authors.lastname: Kato
authors.forename: O
authors.initials: O
authors.lastname: Hashimoto
authors.forename: R
authors.initials: R
authors.lastname: Fukuda
authors.forename: T
authors.initials: T
authors.lastname: Koyama
authors.forename: K
authors.initials: K
authors.lastname: Matsuo
authors.forename: Y
authors.initials: Y
authors.lastname: Okabe
authors.forename: S
authors.initials: S
authors.lastname: Nanko
authors.forename: H
authors.initials: H
authors.lastname: Hohjoh
authors.forename: K
authors.initials: K
authors.lastname: Tokunaga
mesh_terms: D000328:Adult; D017668:Age of Onset; D005260:Female; D015798:HLA-DR1 Antigen / Q000032:analysis* / Q000235:genetics; D006650:Histocompatibility Testing; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D012307:Risk Factors; D012559:Schizophrenia / Q000453:epidemiology* / Q000235:genetics; D012621:Seasons; D012737:Sex Factors
chemical_list: D015798:HLA-DR1 Antigen