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 retinopathy. METHODS: (CA)n repeat length was investigated in the 5' upstream region of the gene coding for aldose reductase (AR), which is a key enzyme of the polyol pathway and plays a role in hyperglycaemia-induced tissue damage, in Japanese patients with Type 2 DM. RESULTS: The dinucleotide repeat length was significantly associated with proliferative 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' upstream region of the AR gene is associated with diabetic retinopathy. These data suggest that the AR locus plays a role in genetic susceptibility to diabetic retinopathy and that dinucleotide repeats in genomic DNA may be related to disease predisposition.