Association study between the MDR1 gene and clinical characteristics in schizophrenia.

OBJECTIVE Schizophrenia is a complex psychiatric disorder, characterized by disturbed patterns of thought and affecting 0.3-2.0% of the world population. Previously, the multidrug resistance 1 (MDR1) gene has been associated with schizophrenia in treatment response studies in psychotic patients. The aim of this study was to determine the association between MDR1 gene polymorphisms and clinical characteristics in patients with schizophrenia. METHODS Positive and negative symptoms of schizophrenia were assessed with the Scale for the Assessment of Negative Symptoms (SANS) and the Scale for the Assessment of Positive Symptoms (SAPS) in 158 Mexican patients with schizophrenia. Analyses of MDR1 gene polymorphisms were performed using TaqMan technology. A multivariate ANOVA was performed with MDR1 polymorphisms and gender as independent variables. RESULTS Males with the G/G genotype of MDR1 rs2032582 presented significantly higher levels of delusions (p = 0.02). When comparing female vs. male groups, the difference was statistically significant (p = 0.0003). Analyses of the MDR1 gene rs1045642 variant showed no significant differences. CONCLUSION Our findings suggest that male carriers of the G allele of variant rs2032582 exhibit greater severity of delusions; however, these results should be taken as preliminary, and replication studies in other populations of different ethnic origins are required to confirm these findings.