Hemoglobin E: A balanced polymorphism protective against high parasitemias and thus severe P falciparum malaria

Abstract

Hemoglobin E is very common in parts of Southeast Asia. The possible malaria protective effects of this and other inherited hemoglobin abnormalities prevalent in Thailand were assessed in a mixed erythrocyte invasion assay. In vitro, starting at 1% parasitemia, Plasmodium falciparum preferentially invaded normal (HbAA) compared to abnormal hemoglobin (HbH, AE, EE, HCS, β-thalassemia E) red cells (HRBCs). The median (range) ratio of parasitization of HRBCs (n = 109) compared to the controls of different major blood groups was 0.40 (0.08, 0.98), less than half that of the normal red cells (NRBCs) compared to their controls 0.88 (0.53, 1.4; P = .001). The median (range) parasitemia in the HRBCs..