Abstract: ObjectiveTo study the relationship between polymorphism of (AC)n in 5′end of the AR gene and background diabetic retinopathy(BDR). Methods74 patients with diabetes mellitus (DM), of them, 39 with BDR and 35 without, and 40 controls were enrolled in this study. PCRagarose gel electrophoresise was used to determine the polymorphism marker of (AC)n dinucleotide of 5′end of the AR gene. Results① 7 alleles, mostly were Z, Z＋2, and Z-2 alleles were observed in type 2 diabetes mellitus and controls. ② Frequency of allele Z-2 was significantly higher in the BDR group than in the nondiabetic retinopathy(NDR) group and the control group, however, frequency of allele Z+2 was significantly lower in the BDR group than in the NDR group and the control group. Conclusion 7 alleles were found in 5′end of the AR gene in type 2 DM patients in the Shandong area, of them, Z-2 allele might be the susceptible gene and Z＋2 allel might be the protective gene.

Key words: Diabetes Mellitus, type 2, Aldose Reductase, Genes, Retinopathy