Haptoglobin gene polymorphism and oxidative stress among sickle cell patients in Uganda

Abstract

Haptoglobin binds cell-free haemoglobin to form haptoglobinhaemoglobin complex that is cleared by CD136 receptors on monocytes thus reducing oxidative stress. However, haptoglobin locus is polymorphic with two codominant alleles Hp1 and Hp2 producing three distinct phenotypes (Hp1-1, Hp2-1, and Hp2-2) with different binding affinities for cell-free haemoglobin and CD136 receptors. This study investigated the role of polymorphism in haptoglobin gene on oxidative stress in sickle cell Patients in Uganda. Methods: A case-control study was undertaken to compare the levels of plasma haemoglobin, malondialdehyde and distribution of haptoglobin genotypes. Genotyping for sickle cell disease was performed by single tube allele specific PCR and Haptoglobin gene polymorphisms were determined by convectional PCR genotyping. Plasma hemoglobin and malondialdehyde levels were determined by Drabkin’s method and TBA assay respectively. Results: Out of 42 participants, 21 (50%) were SCD patients and 21 (50%) were healthy control individuals. The mean concentration of plasma hemoglobin was higher in Sickle cell disease patients (0.9952g/dl) than healthy controls (0.7143g/dl) though not statistically significant (P = 0.2593). Although not significantly different (P = 0.5187), the mean concentration of plasma MDA was lower in SCD patients (4.432µM) than healthy controls (4.706µM). Hp 2-1 was the most prevalent genotype but Hp 1-1 was more prevalent in sickle cell disease patients than healthy controls and was associated with low plasma MDA concentrations