Lymphocyte DNA damage and plasma antioxidant status in Korean subclinical hypertensive patients by glutathione S-transferase polymorphism

BACKGROUND/OBJECTIVES: Glutathione S-transferase (GST) forms a multigene family of phase II detoxification enzymes which are involved in the detoxification of xenobiotics by conjugating substances with glutathione. The aim of this study is to assess the antioxidative status and the degree of DNA damage in the subclinical hypertensive patients in Korea using glutathione S-transferase polymorphisms. SUBJECTS/METHODS: We examined whether DNA damage and antioxidative status show a difference between GSTM1 or GSTT1 genotype in 227 newly diagnosed, untreated (systolic blood pressure (BP) ≥ 130 mmHg or diastolic BP ≥ 85 mmHg) subclinical hypertensive patients and 130 normotensive subjects (systolic BP < 120 mmHg and diastolic BP < 80 mmHg). From the blood of the subjects, the degree of the DNA damage in lymphocyte, the activities of erythrocyte superoxide dismutase, the catalase, and the glutathione peroxidase, the level of glutathione, plasma total radical-trapping antioxidant potential (TRAP), anti-oxidative vitamins, as well as plasma lipid profiles and conjugated diene (CD) were analyzed. RESULTS: Of the 227 subjects studied, 68.3% were GSTM1 null genotype and 66.5% were GSTT1 null genotype. GSTM1 null genotype had an increased risk of hypertension (OR: 2.104, CI: 1.38-3.35), but no significant association in GSTT1 null genotype (OR 0.982, CI: 0.62-1.55). No difference in erythrocyte activities of superoxide dismutase, catalase, or glutathione peroxidase, and plasma TRAP, CD, lipid profiles, and GSH levels were observed between GSTM1 or GSTT1 genotype. Plasma levels of α-tocopherol increased significantly in GSTT1 wild genotype (P < 0.05); however, plasma level of β-carotene increased significantly in GSTT1 null genotype (P < 0.01). DNA damage assessed by the Comet assay was significantly higher in GSTM1 null genotype than wild genotype (P < 0.05). CONCLUSIONS: These results confirm the association between GSTM1 null genotype and risk of hypertension as they suggest that GSTM1 null genotype leads to an increased oxidative stress compared with wild genotype.