Enrichment of rare genetic variants in astrocyte gene enriched co-expression modules altered in postmortem brain samples of schizophrenia

The transcriptome profiles of the cingulate gyrus region from the postmortem brain tissues of a set of well characterized patients with schizophrenia (SCZ) and matched controls were investigated using an integrated approach that analyzed both the alterations in transcription expression pattern and rare genetic variants in expressed genes. We demonstrated increased expression of astrocyte-related genes using spatiotemporal co-expression modules that have previously been established for developing human brain, and showed these results are independent of medication dosage. The relationship between genetic variants and expression pattern in the context of neurodevelopment was further investigated, and we identified an enrichment of rare genetic variants in a set of signature genes that were specific to astrocytes and up-regulated in the patients with SCZ. Our result suggested the involvement of astrocyte malfunction in SCZ pathophysiology. In addition, our approach indicated a novel strategy of narrowing down genetic variants that might contribute to the pathophysiology in the patients with SCZ to a subset of genes that are highly expressed in an affected brain region.