Relationship between glutathione S-transferase M1 polymorphism and clinical outcomes in Chinese peritoneal dialysis patients.

Oxidative stress contributes to cardiovascular diseases in peritoneal dialysis (PD) patients. Glutathione S-transferase M1 is an antioxidative enzyme encoded by the GST M1 gene. The GST M1 (-) genotype causes deficiency of the enzyme when compared with the GST M1 (+) genotype. We investigated the effects of the GST M1 (-)/(+) polymorphism on the clinical outcomes of Chinese PD patients. We studied 441 new PD patients (232 men, age 56.6 ± 13.5 years). GST M1 (-)/(+) polymorphism was determined by multiplex polymerase chain reaction. The patients were followed for 41.4 ± 18.2 months. The GST M1 polymorphism was not associated with 5-year patient and technique survival in the whole cohort. However, there were significant interactions between age group and the GST M1 polymorphism on 5-year patient survival (p=0.046) and technique survival (p=0.049). Post hoc analysis showed that for patients =70 years old, those with the GST M1 (+) genotype had significantly better 5-year patient survival (62.5% vs. 26.2%; log rank test, p=0.012) and technique survival (55.1% vs. 21.9%; log rank test, p=0.024) than the GST M1 (-) group. For patients younger than 70 years, the GST M1 polymorphism did not affect 5-year patient or technique survival. The GST M1 (+) genotype is associated with better survival in elderly PD patients, who may have heavy oxidative stress as a result of the aging and PD processes.