The results obtained indicate that both <i>GSTM1-null</i> and <i>GSTT1-active</i> genotypes are associated with increased POAG risk among smokers, suggesting potential gene-environment interaction in glaucoma development.
By pooling all the studies, either GSTM1 or GSTT1 null polymorphism was not associated with a POAG risk, and this negative association maintained in Caucasian.
The results by ethnicity showed that the association between the GSTM1 null genotype and risk for POAG is statistically significant in East Asians (OR=1.41, 95% CI=1.04-1.90, p=0.026), but not in Caucasians (OR=1.13, 95% CI=0.69-1.84, p=0.638) and Latin-American (OR=1.09, 95% CI=0.62-1.92, p=0.767).
In GSTM1-GSTT1 interaction analysis, individuals with dual null genotype were associated with a significantly increased risk of POAG when compared with the dual present genotype.
Through PCR amplification, we analyzed the GSTM1 gene in DNA samples from 25 patients with POAG and 25 controls; 14 of the patients presented the GSTM1 gene null polymorphism while only eight of the control group had this gene.Although the POAG patients had a higher frequency of GSTM1, the difference was not significant (P = 0.0874); this lack of significance could be due to the small sample size.
The GSTM1 positive genotype and GSTT1 null genotype or the combination of both may be associated with the increased risk of development of POAG in the Turkish population.