en Cellular and molecular Neuroscience Cellular and molecular Neuroscience Original Original <div style="text-align: justify;"><strong>Introduction:</strong> Genetic and environmental factors are involved in the incidence of schizophrenia and bipolar disorder. Many reports confirm that several common genes are connected with these two psychotic disorders. Several neurotransmitters may be involved in the molecular mechanisms of schizophrenia and bipolar disorder. We aimed to estimate the role of two talent genes: DAOA in neurotransmission of glutamate and COMT in neurotransmission of dopamine to guide the treatment of schizophrenia and bipolar disorder.&nbsp;<br> <strong>Methods:</strong> Blood samples (n=100 for schizophrenia, n=100 for bipolar I disorder and n=127 for case control) were collected from individuals unrelated in the southwest of Iran. The SNPs (rs947267 and rs3918342 for DAOA gene/ rs165599 and rs4680 for COMT gene) were genotyped using the PCR-RFLP method. Our finding was studied by logistic regression and Mantel-Haenszel Chi-square tests.<br> <strong>Results:</strong> We observed an association in rs3918342, rs165599 and rs4680 single nucleotide polymorphisms and schizophrenia and bipolar I disorder. In addition, our data demonstrated that the rs947267 was related to bipolar I disorder but there was no association between this SNP and schizophrenia.<br> <strong>Conclusion:</strong> In conclusion, this result supports the hypothesis that variations in DAOA and COMT genes may play a role in schizophrenia and bipolar disorder.</div> Catechol-O-methyltransferase, D-amino acid oxidase activator, Genetics, Schizophrenic disorders, Bipolar disorder 429 438 http://bcn.iums.ac.ir/browse.php?a_code=A-10-1073-1&slc_lang=en&sid=1 Leila Ahmadi leilookahmadi@gmail.com 13700319475328460018416 13700319475328460018416 No Department of Genetics, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran. Seyed Reza Kazemi Nezhad kazemi_reza@yahoo.de 13700319475328460018417 13700319475328460018417 Yes Department of Genetics, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran. Parisima Behbahani behbahani.p@scu.ac.ir 13700319475328460018418 13700319475328460018418 No Department of Genetics, Faculty of Sciences, Shahid Chamran University of Ahvaz, Ahvaz, Iran. Nilofar Khajeddin khajeddinn@gmail.com 13700319475328460018419 13700319475328460018419 No Department of Psychiatry, School of Medicine, Ahvaz Jundishapur University of Medical Sciences, Ahvaz, Iran. Mehdi Pourmehdi-Boroujeni pourmehdim@yahoo.com 13700319475328460018420 13700319475328460018420 No Department of Food Hygiene, Faculty of Veterinary Medicine, Shahid Chamran University of Ahvaz, Ahvaz, Iran.