EPO and proliferative diabetic retinopathy: Because erythropoietin is a potent retinal angiogenic and pro-survival factor implicated in proliferative diabetic retinopathy, a genotype/allele associated with lower EPO expression (the CC variant in our cohort) plausibly confers protection against pathological retinal neovascularization, whereas alleles that increase EPO expression promote DR — a point supported by existing genetic and meta-analytic studies [20,50].