Background: The IL-10 promoter polymorphisms -1082G/A, -819C/T, and -592C/A have been consistently associated with type 2 diabetes (T2DM). We examined whether these polymorphisms variants are also associated with progression of diabetic nephropathy (DN).
Methods: These promoter variants were genotyped in 917 T2DM patients comprising 515 DN patients and 402 control patients without nephropathy (DWN), together with 748 non-diabetic control subjects. Haplotype analysis and multivariate regression analysis were employed in assessing the contribution of IL-10 haplotypes to DN risk, using genotype, clinical and biochemical profile, and their interactions as predictors of DN.
Results: Carriers of mutant -592A and -819T alleles, and -819T/T, -592A/A, and -819C/T genotypes were more frequent in T2DM. However, the -819C/T genotype appeared to be protective of DN, since lower frequency -819T allele and -819C/T genotype were seen in DN patients. Regression analysis identified -1082G/-819T/-592A (GTA) and -1082G/-819T/-592C (GTC) haplotypes as DN-protective haplotypes. Relative to the -1082G/-819C/-592C haplotype, GTA [P = 0.044; odds ratio (OR) = 0.54, 95% confidence interval (CI): 0.30-0.98] and GTC (P = 0.045; OR = 0.56, 95% CI: 0.31-0.99) haplotypes were associated with decreased odds ratio (OR) for DN, after controlling for a number of covariates (age, sex, body mass index (BMI), hypertension, glucose, HbA(1c), DN duration, total cholesterol).
Conclusions: Our results indicate that genetic variations at the IL-10 promoter influence the risk of nephropathy in T2DM patients and thus represent a potential DN genetic-susceptibility locus worthy of replication.
Copyright 2009 John Wiley & Sons, Ltd.