Association between erythropoietin gene polymorphisms and diabetic retinopathy.

OBJECTIVE To determine whether sequence variation in the erythropoietin gene (EPO) is associated with the development of diabetic retinopathy (DR). METHODS This was a multicenter study based on 518 subjects with long-standing diabetes mellitus (DM), 173 with type 1 DM (T1DM) and 345 with type 2 DM (T2DM). Study groups consisted of 233 control subjects with no DR, 155 subjects with nonproliferative DR, 126 with proliferative DR, and 90 with clinically significant macular edema. Subjects with end-stage renal disease were excluded. DNA extracted from blood of each subject was genotyped for 3 EPO single-nucleotide polymorphisms (SNPs). RESULTS All 3 SNPs in EPO were associated with overall DR status in the combined T1DM and T2DM and T2DM alone groups (CC genotype of rs507392, P < .008; GG genotype of rs1617640, P < .008; and CC genotype of rs551238, P < .008) in the multivariate analysis. The GCC haplotype was also associated with overall DR status in the combined DM and T2DM alone groups (P = .008) by multivariate analysis. All SNPs and the GCC haplotype were also associated with proliferative DR and clinically significant macular edema in the combined DM and T2DM alone groups. No associations were found with T1DM alone. CONCLUSION Sequence variation in EPO is associated with the risk of DR independent of duration of DM, degree of glycemic control, and nephropathy. CLINICAL RELEVANCE Identifying EPO genetic markers for high risk of developing DR could lead to the possibility of developing novel treatments or preventive therapies.