Association study of interferon gamma (IFN-γ) +874T/A gene polymorphism in patients with paranoid schizophrenia.

Schizophrenia is a multifactorial disease with changes affecting the immune system. Dysregulation of the cytokine network in schizophrenia has been well documented. Such changes may occur due to disturbances in cytokine levels that are linked to polymorphisms of cytokine genes. However, research in the role of cytokine gene polymorphisms in schizophrenia has been surprisingly scanty. The aim of this study was to identify, in a case control study, whether polymorphism of IFN-γ gene is a risk factor for the development of paranoid schizophrenia. To the best of our knowledge, this is the first study that examines the association between the IFN-γ gene polymorphism and psychopathological symptoms in patients with paranoid schizophrenia. Polymorphism of IFN-γ (+874T/A, rs 62559044) in schizophrenic patients (n=179), as well as healthy individuals (n=196), both Polish residents, was genotyped using AS-PCR method. Of note, when analyzing the results, we took into consideration the gender of studied individuals. Surprisingly, a single-nucleotide polymorphism in the first intron of the IFN-γ gene was found to be associated with paranoid schizophrenia in males, but not in females. The presence of allele A at position +874 in the IFN-γ gene correlates with 1.66-fold higher risk of paranoid schizophrenia development in males. Differences in the genotypes may have an important role in determining the level of I gene transcription. Because other polymorphisms have been demonstrated to influence IFN-γ transcription, further analysis is necessary to clarify the role of this gene in the pathogenesis of paranoid schizophrenia.