Lack of association of GSTT1 and GSTP1 genes methylation and their expression profiles with risk of NAFLD in a sample of Iranian patients

Reactive oxygen species can affect many cellular functions through protein oxidation or initiation of the lipid peroxidation cascade that can lead to non-alcoholic fatty liver disease (NAFLD), characterized by significant lipid deposition in the hepatocytes of patients with no history of excess alcohol intakes. The present study aimed to analyze the methylation status of the antioxidative stress genes GSTT1 (glutathione S-transferase theta-1) and GSTP1 (glutathione S-transferase pi-1), and their expression profiles, in a sample population of patients with NAFLD living in South-East Iran.

Patients and methods: Peripheral blood samples were obtained from 80 NAFLD patients and 80 healthy controls. Promoter methylation of the GSTT1 and GSTP1 genes were analyzed by methylation-specific polymerase chain reaction (MS-PCR). Expression profiles of these genes were also examined by quantitative real-time PCR analysis.

Results: Promoter methylation of the GSTT1 gene was detected in 86.2% of cases and in 91.2% of controls and, of the GSTP1 gene, in 88.8 and 87.5% of cases and controls, respectively. Promoter methylation of GSTT1 and GSTP1 was not statistically different in cases compared with healthy controls. Similarly, mRNA expression levels showed no statistically significant variations between healthy individuals and patients with NAFLD.

Conclusion: Our findings indicate no association between methylation status and expression profiles of GSTT1 and GSTP1 genes and NAFLD. This is the first report to assess such associations in a sample of the Iranian population.