Numerous studies have identified the neuregulin 1 (NRG1) gene as a risk factor for the development of schizophrenia in various populations (Stefansson et al, 2002; Williams et al, 2003; Yang et al, 2003; Shyu et al, 2004; Tang et al, 2004; Harrison & Weinberger, 2005; Mei & Xiong, 2008). This evidence concerns the gene NRG1 and schizophrenia.