RESUMEN
<p><b>OBJECTIVE</b>To investigate the relationship between the -308G/A, -857C/T and -1031T/C of tumor necrosis factor alpha gene (TNF- alpha), -174G/C and -572C/G of interleukin-6 gene (IL-6) polymorphisms and schizophrenia.</p><p><b>METHODS</b>Genomic DNA was isolated from the venous blood leukocytes of 346 unrelated patients with schizophrenia and 323 healthy unrelated individuals (control group). All of the polymorphisms were genotyped by PCR-restriction fragment length polymorphisms (PCR-RFLP). Genotype and allele frequencies were analyzed by SPSS13.0 software.</p><p><b>RESULTS</b>There were significant differences in both allele and genotype frequencies of -857C/T of TNF-alpha gene between the schizophrenia and control groups (P< 0.05). The allele T of -857C/T in schizophrenia group was significantly higher than that in control group (chi-square was 9.414, P=0.002, OR=1.511, 95%CI:1.160-1.969). In addition, there were significant differences in the positive and negative syndrome scale (PANSS) total score and negative symptoms between the patients with different -857C/T genotypes, and the negative symptom score of TT genotype was significantly higher than that of CC genotype (P<0.05).</p><p><b>CONCLUSION</b>There is an association between -857C/T of TNF-alpha gene and schizophrenia, individuals with T allele of -857C/T are susceptible to schizophrenia, and there is an association between -857C/T and negative symptom score.</p>