No association between the tumor necrosis factor-alpha gene promoter polymorphisms and schizophrenia in a Japanese population

Tumor necrosis factor-alpha (TNF-alpha) is a pleiotrophic cytokine and exerts neuroprotective and neurodegenerative effects in brain. Several studies have indicated that TNF-alpha is likely related to the pathogenesis of schizophrenia. Recent genetic investigations have revealed that a TNF-alpha gene promoter polymorphism (-G308A) is associated with schizophrenia, although negative findings have also been reported. To assess whether the TNF-alpha gene promoter variants including -G308A could be implicated in vulnerability to schizophrenia, we conducted a case-control association analysis (265 cases and 424 controls) and the transmission disequilibrium test (TDT) analysis (83 trios) for four polymorphisms (-G238A, -G308A, -C857T and -T1031C) in Japanese subjects. In a case-control analysis, there was no significant association between the promoter polymorphisms or haplotypes in the TNF-alpha gene and schizophrenia. In the TDT analysis, we also did not observe transmission distortion. Our results suggest that the above four polymorphisms in the promoter region of the TNF-alpha gene appear not to confer increased susceptibility for schizophrenia in a Japanese population.