[Phenotypic Variants of Paraoxonase Q192R in Bipolar Disorder,Depression and Schizophrenia]

Activity of the paraoxonase 1 (PON1) enzyme varies prominently according to the PON1 Q192R genotype. The arginine (R) genotype hydrolyzes peroxided lipids more quickly and efficiently than the glutamine (Q) genotype. The Q phenotype suggests greater liability to neurodegenerative processes, cardiovascular and malignancy risks than the R phenotype. Stimulated PON/ARES ratio is associated with the PON1 Q192R polymorphism. This study aimes to assess the Q192R phenotype in schizophrenia, bipolar disorder and depression.

Patients with schizophrenia (37), bipolar disorder (n=50), depression (n=43) and healthy volunteers (n=43) were enrolled. Serum PON1, stimulated paraoxonase (sPON) and aryl esterase (ARES) levels were assessed with an automatic analyzer. Clusters of sPON/ARES ratio were detected with frequency analysis in PON1. QQ, QR and RR variant groups.

There were significant differences between the bipolar disorder, depression, schizophrenia and healthy volunteer groups in terms of phenotype frequencies in groups (Fisher's Exact Coefficient=18.96, p=0.003). A higher prevalence of the PON1 RR variant was found in bipolar disorder whereas the PON1 QQ variant had a higher prevalence in depression and schizophrenia as compared to others. Serum PON1 activity correlated with number of episodes in the bipolar disorder group and with SANS, SAPS scores in the schizophrenia group.

Difference between bipolar disorder, schizophrenia and depression in PON1 activity and PON1 phenotype might be suggestive of different liability to lipid peroxidation and neurodegeneration between the diagnostic groups. Longitudinal studies may identify long term differences between PON1 Q192R polymorphisms in clinical outcomes and neuropathology.