Parasitaemia was significantly lower among cases with severe malaria and sickle-cell trait compared with those with severe malaria and normal haemoglobin (p=3·66 × 10−6), among homozygotes for the derived allele (GG) at rs1541255 of ATP2B4 compared with homozygotes for the ancestral allele (AA; p=0·04), and among children with blood group O compared with non-blood group O cases (p=0·02). This evidence concerns the gene ATP2B4 and malaria.