The association of Haptoglobin polymorphism with Crohn's disease in Israel

Abstract

Objectives Haptoglobin is a α 2-sialoglycoprotein with hemoglobin binding capacity. Functional differences between the Hp phenotypes with the Hp 1-1 protein being a superior anti-inflammatory to the Hp 2-2 protein have been identified. The aim of our study was to investigate the possible role of Hp polymorphism in the susceptibility to Crohn's disease and its clinical course. Methods Hp phenotypes were determined for 382 Israeli CD patients and 3243 healthy controls. Phenotypic data for all Crohn's disease patients were carefully characterized. Analysis was preformed to evaluate the association between Hp polymorphism and Crohn's disease. Results The frequency of Haptoglobin 1-1 was lower in Crohn's disease patients than in healthy individuals (6.28% vs. 9.28%, P = 0.057). There was no association between Haptoglobin phenotypes and disease location, behavior or extra-intestinal manifestations. No association was found between the Haptoglobin polymorphism and the frequency of the three Crohn's disease associated NOD2 mutations examined. Conclusions We found a borderline significant decrease of the Haptoglobin 1-1 phenotype in Israeli Crohn's disease patients compared to healthy controls. Our findings may support the importance of inflammation in Crohn's disease pathogenesis and the protective function of Haptoglobin 1-1 in the susceptibility for Crohn's disease.