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Low plasma haptoglobin is a risk factor for life-threatening childhood severe malarial anemia and not an exclusive consequence of hemolysis

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journal contribution
posted on 25.06.2020 by Samuel Eneọjọ Abah, Florence Burté, Sandrine Marquet, Biobele J Brown, Francis Akinkunmi, Gbeminiyi Oyinloye, Nathaniel K Afolabi, Samuel Omokhodion, Ikeoluwa Lagunju, Wuraola A Shokunbi, Mats Wahlgren, Hélia Dessein, Laurent Argiro, Alain J Dessein, Boris Noyvert, Lilian Hunt, Greg Elgar, Olugbemiro Sodeinde, Anthony A Holder, Delmiro Fernandez-Reyes
Severe Malarial Anemia (SMA), a life-threatening childhood Plasmodium falciparum malaria syndrome requiring urgent blood transfusion, exhibits inflammatory and hemolytic pathology. Differentiating between hypo-haptoglobinemia due to hemolysis or that of genetic origin is key to understand SMA pathogenesis. We hypothesized that while malaria-induced hypo-haptoglobinemia should reverse at recovery, that of genetic etiology should not. We carried-out a case-control study of children living under hyper-endemic holoendemic malaria burden in the sub-Saharan metropolis of Ibadan, Nigeria. We show that hypo-haptoglobinemia is a risk factor for childhood SMA and not solely due to intravascular hemolysis from underlying schizogony. In children presenting with SMA, hypo-haptoglobinemia remains through convalescence to recovery suggesting a genetic cause. We identified a haptoglobin gene variant, rs12162087 (g.-1203G > A, frequency = 0.67), to be associated with plasma haptoglobin levels (p = 8.5 × 10-6). The Homo-Var:(AA) is associated with high plasma haptoglobin while the reference Homo-Ref:(GG) is associated with hypo-haptoglobinemia (p = 2.3 × 10-6). The variant is associated with SMA, with the most support for a risk effect for Homo-Ref genotype. Our insights on regulatory haptoglobin genotypes and hypo-haptoglobinemia suggest that haptoglobin screening could be part of risk-assessment algorithms to prevent rapid disease progression towards SMA in regions with no-access to urgent blood transfusion where SMA accounts for high childhood mortality rates.

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