NRG1 and schizophrenia: Multiple risk haplotypes and genetic polymorphisms in both the 5′ and 3′ regions of the NRG1 gene have been linked to schizophrenia41 Variants linked to schizophrenia have been shown to alter transcription factor binding and to increase transcription of specific NRG1 isoforms, and have been associated with abnormal cortical function and psychotic symptoms14,42.