Association of glutathione s-transferase gene methylation with risk of schizophrenia in an Iranian population. 
It has been believed that epigenetic changes play a critical role in schizophrenia through improper interaction between genome and environmental risk factors.  The aim of this case-control study was to investigate the association of the promoter hypermethylation status of glutathione S-transferase T1 (GSTT1) and glutathione S-transferase P1 (GSTP1) genes with the risk of schizophrenia.  Methylation-specific PCR was used to estimate DNA methylation in the blood of 80 patients with schizophrenia and 71 healthy controls.  Promoter hypermethylation analysis of GSTT and GSTP indicated a significant difference between individuals with methylated and unmethylated status [odds ratio (OR) = 0.339, 95% confidence interval (95% CI) = 0.14-0.8, p = 0.012 and OR = 0.308, 95% CI = 0.135-0.7, p = 0.005, respectively].  The present study supports the hypothesis that impairment in the promoter region of GSTT and GSTP genes by hypermethylation may increase the risk of schizophrenia.