NRG1 function is mediated by a class of receptor tyrosine kinases including erbB4 (Li et al., 2007), and has been shown to associate with schizophrenia (Law et al., 2007) with altered NRG1/erbB4 signaling being reported in the brains of schizophrenia patients (Hahn et al., 2006). This evidence concerns the gene NTRK1 and schizophrenia.