No association between the promoter variants of tumor necrosis factor alpha (TNF-α) and schizophrenia in Chinese Han population

An increasing amount of evidence suggests that the pathophysiology of schizophrenia is associated with activation of the immune system. Four studies have established an association of -308G/A polymorphism of tumor necrosis factor alpha (TNF-α), a cytokine involved in inflammatory processes, with schizophrenia [Mol. Psychiatry 6 (2001) 79; Mol. Psychiatry 8 (2003) 718; Schizophr. Res. 65 (2003) 19; Biol. Psychiatry 54 (2003) 1205]. In the present study, however, no significant positive association has been found between any individual SNP or haplotype constituted of the five promoter polymorphisms (-1031T/C, -863C/A, -857C/T, -308G/A and -238G/A) in the human TNF-α gene and schizophrenia (314 Chinese Han schizophrenic patients and 340 healthy control). A meta-analysis we did in this work, which is based on previous nine studies plus our own unpublished data including a total of 2399 schizophrenic patients (sporadic cases 2099, familial cases >505) and more than 3261 controls, failed to show significant difference of -308G/A distribution between patients and controls in both the whole sample and the pooled Asian sample. By contraries, the significant results in the pooled Caucasian sample imply an ethnic heterogeneity in -308G/A variation in the TNF-α gene in schizophrenia.