Genotype-phenotype Analysis of Paraoxonase 1 in Schizophrenic Patients Treated with Atypical Antipsychotics

OBJECTIVE: Recent studies suggest a possible involvement of low paraoxonase 1 (PON1) enzyme activities in the association between schizophrenia, treatment with atypical antipsychotics and increased cardiovascular (CVD) risk. In the present study, we aimed at investigating the PON1 status in a group of schizophrenic patients treated with either olanzapine or other antipsychotic, as compared to a group of healthy control participants. METHODS: We assessed the arylesterase (AREase) and paraoxonase (POase) activities of PON1, as well as three common polymorphisms of PON1 gene (Q192R, L55M, −108C>T). RESULTS: We found significantly lower (−13.3%) AREase activity in schizophrenic patients, along with significantly lower (−18.2%) POase activity in olanzapine-treated patients with QQ genotype. Furthermore, we found a significant difference between groups in L55M polymorphism distribution, whereas Q192R and −108C>T polymorphisms distributions were similar. CONCLUSION: We identified the olanzapine-treated patients with QQ genotype as having the lowest PON1 (POase) activity, providing a possible way of identifying schizophrenic patients exposed to the greatest risk of CVD.