title: Association between dopamine beta hydroxylase gene polymorphism and age at onset in male schizophrenia.
abstract: OBJECTIVE
  The heterogeneity of schizophrenia mainly results from variations in clinical expressions of the disease, such as age at onset, gender differences in onset of illness, symptoms and response to antipsychotic treatment. Enhanced sensitisation of dopamine pathways in males, having consistently an earlier onset, might be implicated as disease modifiers for schizophrenia in males.
  
  
  METHODS
  In this study, we performed a case (n = 87)-control (n = 100) association study between the DBH5'-ins/del and DBH-444g/a polymorphisms of the DBH gene and also compared the level of psychotic symptoms between patients with different DBH genotypes/haplotypes with respect to antipsychotic therapeutic response and gender difference.
  
  
  RESULTS
  No significant differences between allele and genotype and haplotype frequencies at either groups (p < 0.05). When the age is considered in patient group, a significant difference was observed between patients with ID genotype and with II genotype (p = 0.018). Patients with ID genotype have been diagnosed as schizophrenics in early ages when compared to II genotype carriers. We also found a significant difference between II and ID genotype (p = 0.007) when the gender had taken into account, showing that the ID genotype carriers had an early onset to schizophrenia.
  
  
  CONCLUSIONS
  This association was more significant in male schizophrenia patients than females. Thus, this finding may constitute a novel biological support for the prior finding that onset of schizophrenia varies with gender. The results also showed that critical genetic vulnerability may be associated with the presence or absence of the ID genotype of DBH5'-ins/del.
authors.affiliation: Department of Medical Biology and Genetics, Medical Faculty of Mersin University, Mersin, Turkey.
authors.forename: I Ö
authors.initials: IÖ
authors.lastname: Barlas
authors.affiliation: Department of Psychiatry, GATA Haydarpasa Training Hospital, Istanbul, Turkey.
authors.forename: Umit
authors.initials: U
authors.lastname: Semiz
authors.affiliation: Department of Medical Biology and Genetics, Medical Faculty of Mersin University, Mersin, Turkey.
authors.forename: M E
authors.initials: ME
authors.lastname: Erdal
authors.affiliation: Department of Psychiatry, GATA Haydarpasa Training Hospital, Istanbul, Turkey.
authors.forename: Ayhan
authors.initials: A
authors.lastname: Algül
authors.affiliation: Department of Medical Biology and Genetics, Medical Faculty of Mersin University, Mersin, Turkey.
authors.forename: Ozlem I
authors.initials: OI
authors.lastname: Ay
authors.affiliation: Department of Psychiatry, GATA Haydarpasa Training Hospital, Istanbul, Turkey.
authors.forename: M A
authors.initials: MA
authors.lastname: Ateş
authors.affiliation: Department of Biostatistics, Medical Faculty of Duzce University, Düzce, Turkey.
authors.forename: Handan
authors.initials: H
authors.lastname: Camdeviren
authors.affiliation: Department of Psychiatry, GATA Haydarpasa Training Hospital, Istanbul, Turkey.
authors.forename: Cengiz
authors.initials: C
authors.lastname: Basoglu
authors.affiliation: Department of Psychiatry, Faculty of Medicine, Pamukkale University, Denizli, Turkey.
authors.forename: Hasan
authors.initials: H
authors.lastname: Herken