Genes, Intermediate Phenotypes and Response to Quetiapine RX

Inclusion Criteria: * Provision of written informed consent * Diagnosis of schizophrenia using the Structured Clinical Interview for Diagnosis for the Diagnostic and Statistical Manual of Mental Disorders-Fourth Edition * Male or female patients aged between 18 and 65 years * Female patients of childbearing potential must be using a reliable method of contraception and have a negative urine human chorionic gonadotropin test at enrollment * Able to understand and comply with the requirements of the study * Patients with a cut off value for PANSS more than 75 Exclusion Criteria: * Pregnancy or lactation * Any DSM-IV Axis I disorder not defined in the inclusion criteria * Patients who, in the opinion of the investigator, pose an imminent risk of suicide or a danger to self or others * Known intolerance or lack of response to quetiapine fumarate, as judged by the investigator * Use of any of the following cytochrome P450 3A4 inhibitors in the 14 days preceding enrollment including but not limited to: ketoconazole, itraconazole, fluconazole, erythromycin, clarithromycin, troleandomycin, indinavir, nelfinavir, ritonavir, fluvoxamine and saquinavir * Use of any of the following cytochrome P450 inducers in the 14 days preceding enrollment including but not limited to: phenytoin, carbamazepine, barbiturates, rifampin, St. John's Wort, and glucocorticoids * Administration of a depot antipsychotic injection within one dosing interval before randomization * Patients treated with clozapine within 28 days before the enrollment * Substance or alcohol dependence at enrollment (except dependence in full remission, and except for caffeine or nicotine dependence) * Opiates, amphetamine, barbiturate, cocaine, cannabis, or hallucinogen abuse by DSM-IV criteria within 4 weeks prior to enrollment * Medical conditions that would affect absorption, distribution, metabolism, or excretion of study treatment * Unstable or inadequately treated medical illness (e.g. diabetes, angina pectoris, hypertension) as judged by the investigator * Involvement in the planning and conduct of the study * Previous enrollment or randomization of treatment in the present study * Participation in another drug trial within 4 weeks prior to enrollment into this study or longer in accordance with local requirements * A patient with Diabetes Mellitus * An absolute neutrophil count of ¬1.5 x 109 per liter * Pre-existing Organic Mental Disorder or Mental Retardation.