SLC6A4 and schizophrenia: The aims of this study are to explore (1) whether COMT, 5-HTR2A, and SLC6A4 mRNA expressions are altered in schizophrenia patients; (2) whether COMT, 5-HTR2A, and SLC6A4 mRNA expressions are associated with treatment outcomes, cognitive defects and psychopathological symptoms in schizophrenia; (3) whether antipsychotic treatment has effect on COMT, 5-HTR2A, and SLC6A4 mRNA expressions.