The genes including neuregulin-1 (NRG1), dysbindin (DTNBP1), disrupted in schizophrenia (DISC1), d-amino acid oxidase (DAAO), regulator of G protein signaling-4 (RGSR), catechol-O-methyl transferase (COMT), proline dehydrogenase (PRODH) and G72 are schizophrenia susceptible while several genes affect the glutamatergic transmission pathway in the brain (Craddock et al., 2005; Ross and Margolis, 2005). Here, COMT is linked to schizophrenia.