In recent years, there has been a significant relationship between MTHFR and metabolic syndrome (MS) in certain groups of people with type 2 DM [15] and schizophrenia [16], but these studies have very different results in relation between MTHFR and MS, and no comprehensive study has been done to summarize these outcomes in patients with MS. This evidence concerns the gene MTHFR and schizophrenia.