The −374 T/A polymorphism in the gene encoding RAGE is associated with diabetic nephropathy and retinopathy in type 1 diabetic patients

Abstract

The receptor for AGE (RAGE) is considered to be mainly an intracellular signal-transducer or pro-inflammatory peptide of possible importance for inflammation and autoimmune diseases. Our aim was to study whether the -374 T/A polymorphism in the gene encoding RAGE (AGER) is associated with diabetes type and presence of diabetic complications. The AGER -374 T/A polymorphism was genotyped in 867 type 1 diabetic patients, 2,467 type 2 diabetic patients and 205 non-diabetic control subjects of Scandinavian origin. AGER polymorphism was related to different HLA-DQB1 genotypes and the presence of diabetic complications. Type 1 diabetic patients had a higher frequency of the AGER -374 A/A or T/A genotypes than type 2 diabetic patients (51.1 vs 44.9%, p=0.002) and control subjects (51.1 vs 47.6%, p=0.0006). The RAGE -374 T/A polymorphism was associated with HLA-DQB1 genotypes; patients with HLA risk genotypes had a higher frequency of the A/A or T/A genotypes than patients with other HLA-DQB1 genotypes (60.3 vs 40.3%, p<0.000001). In type 1 diabetic patients, the frequency of the A/A or T/A genotypes was higher in patients with diabetic nephropathy than without (61.1 vs 46.8%, p=0.006) and with sight-threatening retinopathy than without (56.1 vs 47.6%, p=0.03). In type 2 diabetic patients with HbA(1c) values below the median, the T/T genotype was more frequent in patients with diabetic nephropathy than without (54.3 vs 38.2%, p=0.02). Our results show an association between the AGER -374 T/A polymorphism and type 1 diabetes. This association was HLA-DQB1-dependent. The polymorphism was associated with diabetic nephropathy in both type 1 and type 2 diabetes, in an HbA(1c)-dependent manner in the latter group, and also with sight-threatening retinopathy in type 1 diabetic patients.