DLPFC Transcriptome Defines Two Molecular Subtypes of Schizophrenia

Abstract

Little is known about the molecular pathogenesis of schizophrenia, possibly because of unrecognized heterogeneity in diagnosed patient populations. We analyzed gene expression data collected from the dorsolateral prefrontal cortex (DLPFC) of post-mortem frozen brains of 189 adult diagnosed schizophrenics and 206 matched controls. Transcripts from 633 genes are differentially expressed in the DLPFC of schizophrenics as compared to controls at Bonferroni-corrected significance levels. Seventeen of those genes are differentially expressed at very high significance levels (< 10-8 after Bonferroni correction). Weighted Gene Co-expression Network Analysis (WGCNA) of the schizophrenic subjects, based on the transcripts differentially expressed in the schizophrenics as compared to controls, divides them into two groups: "Type 1" schizophrenics, have a DLPFC transcriptome similar to that of controls with no expressed genes identified in this subcohort while the "type 2" schizophrenics have a DLPFC transcriptome dramatically different from that of controls, with 3,652 expression array probes to 3,200 genes detecting transcripts that are differentially expressed at very high significance levels. These findings were re-tested and replicated in a separate independent cohort, using the RNAseq data from the DLPFC of an independent set of schizophrenics and control subjects. We suggest the hypothesis that these striking differences in DLPFC transcriptomes, identified and replicated in two populations, imply a fundamental biologic difference between these two groups of patients who have been diagnosed as schizophrenic.