Analysis of schizophrenia ‘at risk' polymorphisms associated with changes in NRG1 and ErbB4 mRNA levels, as well as a de novo microdeletion of ERBB4, suggest altered NRG/ErbB4 signalling can result in behavioural impairments resembling aspects of schizophrenia44, 49. This evidence concerns the gene NRG1 and schizophrenia.