Prediction of schizophrenia using MAOA-uVNTR polymorphism: A case–control study

CONTEXT: Schizophrenia has been associated with disorder of the dopamine system, which is downregulated by projections of the serotonin pathway. Dopamine and serotonin levels are regulated by a system of transporters and enzymes. In this research, dopamine transporter polymorphism (DAT-VNTR), serotonin transporter polymorphism (5-HTTLPR), monoamine oxidase A (MAOA-uVNTR), and catechol-o-methyl transferase (COMT Val158Met) polymorphisms have been investigated. AIMS: The aim of this study was to asses frequencies of these polymorphisms in the healthy control group and patients and to asses association with schizophrenia. SETTINGS AND DESIGN: Three hundred and fourteen healthy volunteers and 306 schizophrenia patients were included. Schizophrenia was diagnosed by Diagnostic and Statistical Manual-IV of the American Psychiatric Association, and mini international neuropsychiatric interview questionnaire was used for screening of healthy population. MATERIALS AND METHODS: Genotyping was performed using polymerase chain reaction (PCR) reaction followed by gel electrophoresis and PCR-restriction fragment length polymorphism. STATISTICAL ANALYSIS: Categorical data were analyzed using the Chi-square test, age between subgroups was compared using the Mann–Whitney test, and all polymorphisms were tested for Hardy–Weinberg equilibrium. Logistic regression analysis was used to set the prediction model of schizophrenia. RESULTS: Difference in genotype distribution was observed for COMT Val158Met in female and DAT-VNTR polymorphism in overall sample P = 0.021 and P = 0.028, respectively. Statistically significant association of MAOA-uVNTR and schizophrenia was observed after adjustment for anamnestic predictors of disease. P = 0.010, 80.45% participants were correctly classified. CONCLUSION: Our results suggest an association of MAOA-uVNTR polymorphism with schizophrenia. The difference in the distribution of COMT Val158Met and DAT-VNTR polymorphism support the involvement of dopamine system components in the pathogenesis of schizophrenia.