RGS4 Polymorphisms and Neurobiology of Schizophrenia

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DESCRIPTION (provided by applicant): This Research Career Development plan proposes a program of training and research designed to clarify the in vivo biological impact of variations in the gene encoding regulator of G-protein signaling subtype 4 (RGS4) polymorphisms in schizophrenia patients, individuals at risk for schizophrenia and matched healthy subjects. Demonstrating an association between genetic variations and intermediate phenotypes provides an important additional support for genetic association. RGS4 underexpression in the dorsolateral prefrontal cortex (DLPFC) of schizophrenia patients is reported. Subsequently, an association of RGS4 gene with schizophrenia has been reported in 7 independently ascertained populations in USA, Europe, india and Brazil. Our preliminary studies showed smaller DLPFC in schizophrenia patients homozygous for allele T of SNP4 and allele A of SNP18 but not in healthy subjects suggesting an interaction with other illness related variables. According to the neurodevelopmental hypothesis of schizophrenia pathogenic process starts prior to the emergence of clinical symptoms. Therefore, studying cerebral changes in persons at genetically high risk for developing schizophrenia who have not yet manifested the illness could minimize the confounds due to the illness. Smaller DLPFC was also observed in schizophrenia subjects homozygous for Val allele of the COMT gene that has also been associated with schizophrenia. The proposed study plans to utilize structural MRI and phosphorus magnetic resonance spectroscopy to characterize the differences in morphometry and membrane chemical (phosphomonoesters and phosphodiesters) concentrations associated with RGS4 variations in these study groups. We will explore the associations of these imaging measures with COMT polymorphisms. Characterizing intermediate phenotypes using "cross-longitudinal" design helps in delineating longitudinal trajectory of cerebral correlates of genetic polymorphisms, designing novel medications and early detection.