Association of erythropoietin gene polymorphisms with retinopathy in a Chinese cohort with type 2 diabetes mellitus

Background: This study was performed to investigate the correlation of erythropoietin gene polymorphisms with diabetic retinopathy (DR) in a Chinese cohort with type 2 diabetes mellitus (T2DM).

Design: Case-control study held in Qilu hospital of Shandong University, China.

Participants: 792 T2DM individuals were involved, classified as groups DR (n = 448) and non-DR (NDR; n = 344). The DR group was subdivided into groups proliferative DR (PDR; n = 220) and non-PDR (NPDR; n = 228).

Methods: Three single-nucleotide polymorphisms, rs1617640, rs507392 and rs551238, in the erythropoietin gene were genotyped

Main outcome measures: Odds ratios (ORs) for the effects of erythropoietin gene polymorphisms on DR risk.

Results: The genotype CC frequency in rs507392 was significantly lower in DR group (additive: OR, 0.45; 95% confidence interval [CI], 0.23-0.89; P = 0.027; recessive: OR, 0.44; 95%CI, 0.23-0.86; P = 0.012) or PDR group (additive OR, 0.18; 95%CI, 0.05-0.63; P = 0.002; recessive OR, 0.19; 95%CI, 0.06-0.66; P = 0.003) than in NDR group. The genotype CC frequency in rs551238 was significantly lower in DR group (additive OR, 0.42; 95%CI, 0.21-0.38; P = 0.016; recessive OR, 0.40; 95%CI, 0.20-0.79; P = 0.010) or PDR group (additive OR, 0.18; 95%CI, 0.05-0.62; P = 0.002; recessive OR, 0.18; 95%CI, 0.05-0.61; P = 0.002). No significant differences were detected in the distributions of rs1617640 genotype or all polymorphisms' alleles between groups NDR and DR, PDR or NPDR. Haplotype analyses did not provide any evidence for the correlation between the three polymorphisms and DR.

Conclusions: Our data suggest that rs507392 and rs551238 in the erythropoietin gene probably act to lessen the risk for DR and PDR in the Chinese T2DM cohort.