Association of Mn-SOD mutation (c.47T > C) with various POAG clinical indices

To investigate whether the c.47T > C mutation in the manganese superoxide dismutase gene (Mn-SOD) is a risk factor for primary open angle glaucoma (POAG) in the Saudi population.

A cohort of 226 unrelated POAG patients and 403 unrelated control subjects from Saudi Arabia were genotyped for a single nucleotide polymorphism (SNP; rs4880; c.47T > C) utilizing Taq-Man® assay ID: C_8709053_10. The association between mutant genotypes and various clinical indices important for POAG was also investigated.

Among cases, the prevalence of the wildtype genotype (T/T) was 22.1% (50/226), while the heterozygous mutated genotype (T/C) was 50.9% (115/226) and the homozygous mutant genotype (C/C) was 27% (61/226). There were no statistically significant differences between cases and controls in terms of the genotype distribution on both heterozygous mutant (p = 0.916) and homozygous mutant (p = 0.988) genotypes. POAG patients with the mutant genotypes had slightly higher intraocular pressure (IOP) than controls. Additionally, patients with T/C genotype had slight elevation of the cup/disc ratio than the normal group. Additionally, the age at onset of disease showed an increasing trend with severity of mutation where it increases across groups T/T, T/C, and C/C being at [48.9 (±16.3), 51.4 (±12.2), and 56.5 (±13.9)] respectively and a p value of 0.028 for the C/C genotype.

This mutation could be associated with various clinical indices important for POAG. If similar findings were found in other populations and larger cohorts, then this SNP may be used as a marker for assessing the severity of the disease.