Abstract:
Haptoglobin gene encodes for an acute phase protein; Haptoglobin and is expressed in
three different polymorphic forms, Hp1-1, Hp1-2 and Hp2-2. Various studies on pathogenesis
of Malaria maintain that Haptoglobin polymorphism influences host susceptibility to
Plasmodium falciparum infection.
A number of studies provide evidence that,
individuals carrying Hp2-2 genotype are resistant to both Malaria infection and
development of severe disease although some have shown that no influence manifested
by the genotype. The present study aims on drawing clear information on the effect of
the individual host Haptoglobin genotype to Malaria, focusing on the more Malaria
susceptible group; Children under five years of age. The study also investigated how
Plasma Haptoglobin level in the three Haptoglobin genotypes is affected by Malaria
infection. A cohort of 344 under five years of age children in Morogoro was followed for
an average of one year, where each child attended clinic once in every four weeks.
Haptoglobin genotyping was done by PCR while was done by indirect ELISA. Among
the 344 children, the proportion of the three genotypes (Hp1-1; Hp1-2; Hp2-2) was 85; 171;
88 and this obeys the Hardy-Weinberg equilibrium. Microscopic examination of blood
smears found that positive cases for Malaria were 11.7%, 11.6% and 12.4% for the
genotypes Hp1-1, Hp1-2 and Hp2-2 respectively. Haptoglobin levels were significantly
higher with negative parasitemia when compared with Hp1-1 (p=0.01). The variation in
the level of plasma Haptoglobin level due to Malaria infection was significantly higher in
Hp2-2 when compared to Hp1-1 when compared by unpaired t-test (p=0.03). This study
concluded that at the age below five years the Haptoglobin genetic polymorphism neither
influences susceptibility to Malaria infection nor the disease development after infection
and the magnitude of drop in plasma Haptoglobin level due to Malaria infection is higher
in Hp2-2 than in Hp1-1 individuals.
