Promoter Polymorphism of the Anion‐Exchange Protein 1 Associated with Severe Malarial Anemia and Fatality

Abstract

The anion-exchange protein 1 (AE1 or band 3) is involved in the erythrocyte invasion of the malaria parasite Plasmodium falciparum, the adhesion of infected erythrocytes to endothelial cells, and the regulation of acid-base homeostasis, which is a critical factor for human survival in severe malaria. A variant of the AE1 gene promoter 512 base pairs (bp) distant from the transcription start site and 5699 bp from the translation start codon (AE1(-5699T-->C)) has been shown to be highly frequent in a population from the Ashanti region, Ghana. In a matched-pair case-control study (736 pairs), children heterozygous for the mutation (AE1(-5699CT)) had an increased risk of severe malarial anemia (odds ratio [OR], 1.45 [95% confidence interval {CI}, 1.05-2.01]; P<.03). In children who developed this complication, carriers of the mutation AE1(-5699C) had a higher fatality rate than those with the genotype AE1(-5699TT) (relative risk, 7.1 [95% CI, 1.0-52.8]). Moreover, in children with cerebral malaria, AE1(-5699C) was positively associated with a distinctive metabolic acidosis (P<.002), and results of luciferase assays showed higher transcriptional activity of the AE1(-5699C) allele. These results demonstrate that the AE1 promoter allele might influence the infection phenotype and the risk of fatal outcome in children with severe malaria. In this regard, a crucial role of the AE1 protein in malaria is emphasized.