NRG1 and schizophrenia: Both NRG1 and ErbB4 receptor have been identified as candidate risk genes for schizophrenia through genetic studies (Stefansson et al., 2002, 2003; Yang et al., 2003; Corvin et al., 2004; Zhao et al., 2004; Owen et al., 2005; Hahn et al., 2006).