Glutathione S-transferase M1 and T1 polymorphisms in Arab glaucoma patients

Purpose: Glutathione S-transferases (GSTs) are a family of enzymes that inactivate xenobiotics and endogenous end products formed as secondary metabolites during oxidative stress. In humans, GSTT1 and GSTM1 deletion genotypes (T0M1, T1M0, and T0M0) are associated with a variety of pathologic processes including certain ophthalmologic diseases. Methods: We compared the prevalence of GSTT1 and GSTM1 deletion genotypes, which were determined by multiplex polymerase chain reaction, in 107 Arab patients with glaucoma (49 with primary open-angle glaucoma, 29 with pseudoexfoliation glaucoma, and 29 with primary angle-closure glaucoma) to 120 age, sex, and ethnically matched controls. Results: All three GST polymorphisms were significantly more common in the entire glaucoma group (p<0.0167) than in controls. However, when patients were stratified by glaucoma type, the deletion genotype, T0M0, was not particularly associated with any type of glaucoma tested. The T1MO genotype was more common among patients with each type of glaucoma than among controls whereas T0M1 genotype was more common among pseudoexfoliation glaucoma (PEG) and primary open-angle glaucoma (POAG) patients than controls. Conclusions: The overall results indicate a possible variable association between various GSTT1 and GSTM1 genotypes and glaucoma in this population. Decreased GST function might interfere with the metabolism of oxidative intermediates and exacerbate the direct or indirect damaging effects of oxidative stress on the optic nerve. It is possible that these GST polymorphisms may be risk factors for glaucoma.