Association between haptoglobin gene variants and diabetic nephropathy: Haptoglobin polymorphism in nephropathy susceptibility

Background/Aims: The Hp(1)/Hp(2) DNA polymorphism has previously been implicated in susceptibility to diabetic nephropathy in some but not all studies. In an attempt to clarify these conflicting findings, we conducted a case-control association study in a Caucasian population. Methods: We recruited 224 and 285 type 1 diabetic patients with ( cases) and without ( controls) nephropathy, respectively, from 2 centres based in Northern Ireland and the Republic of Ireland. Hp(1)/Hp(2) genotyping was performed using a combination of long-range and multiplex PCR. Allele and genotype frequencies in cases and controls were compared using the chi(2) test. Results: There was a statistically significant increase in the frequency of the Hp(2) allele in cases compared to controls (65.6 vs. 58.6%, OR = 1.35, 95% Cl: 1.04-1.76, p = 0.03). The distributions of genotypes were in Hardy-Weinberg equilibrium for both cases and controls, and the overall frequency of the Hp(1) allele was 38.3%, which is similar to that found in other Western European populations. Conclusions: The results suggest that the Hp(2) allele may confer susceptibility to nephropathy in patients with type 1 diabetes. Copyright (c) 2007 S. Karger AG, Basel.