Dysregulation in D-Ser signaling, potentially due to altered DAAO activity, has been implicated in the NMDAR dysfunctions observed in various diseases, such as familial and sporadic ALS (Mitchell et al., 2010; Paul and de Belleroche, 2012), AD (Tannenberg et al., 2004; Billard, 2008; Madeira et al., 2015) schizophrenia (Verrall et al., 2007; Madeira et al., 2008; Habl et al., 2009) and chronic pain (Zhao et al., 2010; Gong et al., 2011). This evidence concerns the gene DAO and schizophrenia.