Tehran University of Medical Sciences Iranian Journal of Psychiatry 1735-4587 6 1 2011 03 15 1 6 Seyed Masoud Arzaghi Psychosomatic Research Group, Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran, Iran Arash Hossein-Nezhad Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran, Iran Seyed Vahid Shariat Mental Health Research Center, Tehran University of Medical Sciences, Tehran, Iran Alireza Ghodsipour Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran, Iran Jamal Shams Neuroscience Research Center, National Neuroscience Research Network, Shaheed Beheshti University of Medical Sciences, Tehran, Iran Bagher Larijani Endocrinology and Metabolism Research Center, Tehran University of Medical Sciences, Tehran, Iran 2015 10 14 Objective: The methylenetetrahydrofolate reductase (MTHFR) gene polymorphism C677T is suspected to be a risk factor for psychiatric disorders, but it remains inconclusive whether the MTHFR polymorphism C677T is imputed to vulnerability to schizophrenia and bipolar disorder. Method: We prompted impetus to appraise this polymorphism in an Iranian population. Therefore, 90 patients with bipolar disorder type I (BID), 66 patients with schizophrenia diagnosed according to DSM-IV criteria, and 94 unrelated controls with no history of psychiatric disorders were recruited for this study. Genotype distribution and allelic frequencies of C677T polymorphism were investigated. Results: We found no robust differences between patients with BID and schizophrenia with control participants either for allele frequencies or genotype distribution of MTHFR C677T polymorphism. However, a trend toward an increased risk for T allele was observed in the BID patients [with odds ratio (OR) of 1.28(CI 95%: 0.8-1.31), p>0.05]. Conclusion: However, the present and some previous studies failed to elucidate possible interaction between MTHFR C677T polymorphism and vulnerability to schizophrenia and bipolar disorder; still some associations have been revealed in performed meta-analyses that warrant further studies. https://ijps.tums.ac.ir/index.php/ijps/article/view/340 https://ijps.tums.ac.ir/index.php/ijps/article/download/340/336