Abstract
Objective: Schizophrenia (Sch) and bipolar disorder (BD) are debilitating chronic psychiatric disorders that are both etiologically and clinically heterogeneous. According to the gathered evidence, multiple mental disorders are accompanied by inflammation. Interferon-γ (IFN-γ), as a regulatory cytokine, is involved in the immune response as a proinflammatory mediator. Several critical physiological functions are regulated and governed by nitric oxide (NO) in the central nervous system. This study aimed to investigate the association between IFN-γ +874T/A and eNOS 894G/T variants and Sch or BD susceptibility.
Methods: Blood samples were collected from patients and healthy subjects. IFN-γ +874T/A and eNOS 894G/T variants were genotyped with the PCR-RFLP. We evaluated the patients with some clinical parameters (the duration of the disorder, age of onset, number of hospitalizations, family history, tobacco smoking or drug, alcohol usage). Statistical analyses were performed using the SPSS version.
Results: When the genotype distributions and allele frequencies of the IFN-γ +874T/A and eNOS 894G/T in the patients diagnosed with Sch or BD were compared with the control group, there were not found to be significant differences between the groups. When comparing IFN-γ +874T/A and eNOS 894G/T genotype distributions and allele frequencies of Sch or BD patients due to clinical parameters, the genotype distribution of IFN-γ +874T/A in BD patients was significantly different between the groups due to the presence of tobacco smoking (OR: 0.217, 95%Cl: 0.054–0.878; p = 0.032).
Conclusion: To the best of our knowledge, this is the first study that examines the association between the IFN-γ and eNOS gene variants and Sch or BD in a Turkish population. Although IFN-γ +874T/A and eNOS 894G/T variants are not considered as candidate genes for Sch or BD, the results indicated that the BD patients carrying IFN-γ +874T/A AA genotype were less susceptible to tobacco smoking in a Turkish population.

Key words: Schizophrenia, bipolar disorder, eNOS, IFN-�, variant, tobacco smoking