ABO and thalassemia: Strong associations with risk of severe malaria were also seen for polymorphisms in ABO and HBA, including rs8176719 in ABO (representing blood group O; adjusted OR 0·74, 95% CI 0·66–0·72; p=6·26 × 10−8), rs8176746 in ABO (identifying blood group B; 1·38, 95% CI 1·22–1·50; p=2·38 × 10−7), and a 3·7 kb deletion in HBA (−α3·7-thalassaemia; 0·83, 0·76–0·90; p=2·06 × 10−6).