Length rather than a specific allele of dinucleotide repeat in the 5 ' upstream region of the aldose reductase gene is associated with diabetic retinopathy

Aims To assess the possible contribution of a genetic factor to diabetic re tinopathy. Methods (CA)n repeat length was investigated in the 5' upstream region of t he gene coding for aldose reductase (AR), which is a key enzyme of the poly ol pathway and plays a role in hyperglycaemia-induced tissue damage, in Jap anese patients with Type 2 DM. Results The dinucleotide repeat length was significantly associated with pr oliferative diabetic retinopathy (PDR) (P = 0.029, Mann-Whitney U-test); i. e. shorter alleles were more prevalent in the PDR group than in the control group. Conclusions (CA)n repeat length, rather than a specific allele, in the 5' u pstream region of the AR gene is associated with diabetic retinopathy. Thes e data suggest that the AR locus plays a role in genetic susceptibility to diabetic retinopathy and that dinucleotide repeats in genomic DNA may be re lated to disease predisposition.