The functional polymorphism -863 C/A in the TNF-α gene is associated with primary open-angle glaucoma development in Iraqi patients

Abstract

Glaucoma is one of the main causes of irreversible blindness. The most common type of glaucoma is primary open-angle glaucoma (POAG). This study aimed to evaluate the possible association between the −863 C/A TNF-α (tumor necrosis factor-alpha) gene polymorphism and −1562 C/T MMP9 (matrix metallopeptidase 9) gene polymorphisms in POAG. Blood samples from apparently healthy controls and patients (40–70 years) with POAG were taken from Baghdad's Ibn Al-Haitham Teaching Eye Hospital. For detecting TNF-α serum levels in peripheral blood, enzyme-linked immunosorbent assay (ELISA) approaches are utilized. Sequence-specific primers with 3 end mismatches were used to amplify the specific allelic variants of −863 C/A TNF-α by sequence-specific primers -polymerase chain reaction (SSP-PCR). The −1562 C/T MMP9 gene polymorphisms were genotyped by the PCR-restriction fragment length polymorphism (PCR-RFLP) method. The mean TNF-α level was significantly elevated in POAG patients (132.85 ± 5.18 pg/ml, P = 0.001) than in the controls (71.52 ± 2.07). The CC genotype of TNF-α is a risk factor for the development of POAG (56, 74.7 %, OR: 2.3158, 95 % CI: 1.1594–4.6256, p = 0.0174) as compared with CA and AA genotypes. The TNF-α (−863) C allele is a risk factor for POAG development (OR: 2.1095, 95 % CI: 1.2207–3.6452, p = 0.0075). The TNF-α (−863) A allele is protective (OR: 0.4741, 95 % CI: 0.2743–0.8192). The results of MMP9 genotyping reveal that none of the three genotypes (TT, TC, and CC) or the two alleles (T and C) are related to POAG development. In conclusion, High levels of TNF-α are associated with POAG. The CC genotype of TNF-α is a risk factor for the development of POAG as compared with CA and AA genotypes. The TNF-α (−863) C allele is a risk factor for POAG while the TNF-α (−863) A allele is protective. No significant difference among the three genotypes (CC, CT, and TT) with POAG development was observed.