Association analysis of polymorphisms in the prepronociceptin gene and schizophrenia

The human prepronociceptin (ppNoc) gene is located on chromosome 8p21, and several linkage studies have suggested that the susceptibility locus for sc hizophrenia is present in this chromosomal region. We investigated genetic variations in the promoter and coding regions of the ppNoc gene to determin e if there may be an association between naturally occurring mutations and the manifestation of schizophrenia. Association analyses for the variations found were conducted between 87 unrelated schizophrenic patients and 100 h ealthy controls. Polymorphisms were found at both the -503 locus (G/A) in t he promoter region and the 353 locus (Ala118Gly) in exon 3. Additionally, r are variants were identified at the -261 locus (A/G) in the promoter region , the 515 locus (Gln172Arg) in exon 3, and the 561 locus (G/A) in the untra nslated region of exon 3. A significant difference was observed in allele f requency at the 353 locus between controls and patients with continuous-cou rse schizophrenia (P = 0.0237), and between patients with and without promi nent negative symptoms (P = 0.0201). However, neither difference was signif icant after Bonferroni correction. In addition, there were no significant d ifferences in genotype and allele frequencies at either the -503 or 353 loc us between the control group and patients with schizophrenia. These results suggest that ppNoc gene polymorphisms have no association with schizophren ia.