Haptoglobin polymorphism and diabetic nephropathy in Brazilian diabetic patients.

Diabetic nephropathy (DN) has an important impact on morbidity/mortality in diabetic patients. Genetic factors are probably involved in the development of this microvascular complication. Haptoglobin (Hp) is a genetically polymorphic glycoprotein that forms stable complexes with plasma-free hemoglobin (Hb) providing protection against heme-induced oxidative stress and kidney damage. The aim of the present study was to investigate the existence of association between the Hp genotypes and the presence of DN in Brazilian diabetic patients. The Hp genotypes of 265 patients, 95 type 1 diabetes mellitus (DM1) sufferers with at least 10 years of disease and 170 type 2 diabetes mellitus (DM2) sufferers with at least 5 years of disease were determined by allele-specific PCR; both groups included patients with and without DN. Hp allele and genotype frequencies were compared among the patient groups and between the patient groups and a control group of 142 healthy individuals. No association between Hp genotypes and DN could be demonstrated. Additionally, urinary albumin excretion values and the presence or absence of systemic arterial hypertension (SAH) were compared among the patient groups. Again, no significant correlations were found. The Hp polymorphism could not be associated with DN in the population studied here.