Association of erythropoietin gene polymorphism (rs1617640 C>T/G) with diabetic retinopathy in Type 2 diabetes mellitus patients of Punjabi population in Pakistan

Diabetic retinopathy (DR) is a leading cause of vision loss in individuals with type 2 diabetes mellitus (T2DM) and is influenced by genetic factors. We investigated the association between the erythropoietin (EPO) gene polymorphism (rs1617640 C > T/G) and DR risk in a Punjabi Pakistani cohort of adults with T2DM. In a case-control design, 573 T2DM patients (294 with DR, 279 controls without retinopathy, CDR) were genotyped by ARMS-PCR. The protective CC genotype was significantly more frequent in controls (96.77%) than in cases (30.61%) and was associated with markedly reduced DR risk (OR = 68; 95% CI 33.468-138.162; p < 0.001). Conversely, the GG and TT genotypes were absent in controls but present in DR patients (27.55% and 21.43%, respectively) and were strongly associated with increased DR risk (p < 0.001). Allele-level analysis mirrored genotype findings: the C allele predominated in controls (98.39%) but was significantly less frequent in cases (39%), while G and T alleles were enriched among DR patients (p < 0.001). Together, genotype- and allele-based results indicate that the rs1617640 C variant is protective against DR in this Punjabi T2DM population, whereas G and T variants increase DR susceptibility.