Analysis of a polymorphism in the promoter region of the tumor necrosis factor alpha gene in schizophrenia and bipolar disorder: further support for an association with schizophrenia

Sir – Activation of the inflammatory response system has been observed in the schizophrenia and affective disorders.1,2 Investigations of the role of the inflammatory response in these psychiatric disorders include analysis of the immune mediators at the gene level, so the genetic polymorphism of specific cytokine loci has been investigated in psychiatric disorders.3,4 Recently, Boin et al5 investigated a biallelic variant (-G308A) of the TNF- gene directly related to increased production of these cytokines, and found a significant association with schizophrenia. Interestingly, the TNF- gene is located in the region 6p21.1–21.3, near the HLA region, where linkage and association studies have suggested a locus of susceptibility to schizophrenia.6