Activation of the inflammatory response system has been related to the pathophysiology of schizophrenia by several recent studies. Schizophrenic patients have varied levels of proinflammatory cytokines, such as interleukin (IL)-1,-6, and tumor necrosis factor (TNF)␣ in their peripheral blood or cerebrospinal fluid. [1][2][3][4][5][6] These cytokines can modify the metabolism of neurotransmitters, influence neural development, and IL-1 has been implicated in acute, and, on the other hand, chronic neurodegeneration. were somewhat, but not significantly, higher in the schizophrenic patients as compared to the controls. These alleles are known to be located on the same haplotype. 10 The number of carriers of this haplotype was significantly higher in the schizophrenia patients (17/50 vs 81/400) than in the controls (P = 0.026, 2 ). The frequencies of this haplotype were 0.38 and 0.27, respectively (P = 0.0266, 2 ). The number of homozygotes of this haplotype was significantly higher in the schizophrenia patients (P = 0.0006, 2 ). These data suggest that the cytokine aberrations in schizophrenia are, at least partly, genetically determined.