Objective: 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.
Method: 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.
Results: 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.
Conclusion: 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.