Study of eNOS Glu298Asp Polymorphism in Glaucoma Patients in Gilan Population

Glaucoma is the leading cause of irreversible blindness worldwide. It is characterized by degeneration of the retinal ganglion cells and optic nerve damage. Vascular dysregulation plays an important role in the etiology of glaucoma. Nitric oxide (NO) increases blood flow in the vessels of the tissue and helps to overcome the stress. Circulating NO is synthesized in the vascular endothelium by action of endothelial nitric oxide synthase (eNOS). Glu298Asp is one of the common polymorphism of eNOS gene. This study evaluates the association of eNOS ­Glu298Asp polymorphism with glaucoma.
This case-control study included 110 glaucoma patients and 121 controls. Genomic DNA was extracted from peripheral blood leukocytes. Genotypes were detected using a PCR-RFLP method. Statistical analysis was performed using the MedCalc program (version 12.1).
The frequency of GG, GT and TT genotypes in controls were 0.52, 0.42 and 0.06, respectively while in glaucoma patients were 0.6, 0.32 and 0.08, respectively. No significant differences in genotypes frequencies were found between patients and controls (p=0.24, χ²=2.78). In control and patient groups, the frequency of G allele was 0.73 and 0.76, respectively and the frequency of T allele were 0.27 and 0.24, respectively. The allele frequencies did not differ significantly between controls and patients (p=0.56, χ²=0.33).
It is suggested that eNOS Glu298Asp polymorphism may not be associated with the risk factor of glaucoma in the studied population. However, larger and different ethnicities-based populations are required to achieve a definitive conclusion.