GSTM1-null and GSTT1-active genotypes as risk determinants of primary open angle glaucoma among smokers

AIM： To evaluate glutathione transferase theta 1 and mu 1（GSTT1 and GSTM1） polymorphisms as determinants of primary open angle glaucoma（POAG） risk, independently or in combination with cigarette smoking, hypertension and diabetes mellitus.METHODS： A case-control study with 102 POAG patients and 202 age and gender-matched controls was carried out. Multiplex-polymerase chain reaction method was used for the analysis of GSTM1 and GSTT1 polymorphisms. The differences between two groups were tested by the t-test or χ~2 test. Logistic regression analysis was used for assessing the risk for disease development.RESULTS： The presence of GSTM1-null genotype did not contribute independently towards the risk of POAG. However, individuals with GSTT1-active genotype were at almost two-fold increased risk to develop glaucoma（P=0.044） which increased up to 4.36 when combined with GSTM1-null carriers（P=0.024）. When glutathione transferase（GST） genotypes were analyzed in association with cigarette smoking, hypertension and diabetes, only carriers of GSTT1-active genotype had significantly increased risk of POAG development in comparison with GSTT1-null genotype individuals with no history of smoking, hypertension and diabetes, respectively （OR=3.52, P=0.003; OR=10.02, P〈0.001; OR=4.53, P=0.002）. CONCLUSION： The results obtained indicate that both GSTM1-null and GSTT1-active genotypes are associated with increased POAG risk among smokers, suggesting potential gene-environment interaction in glaucoma development.