Previous studies linking ABO blood group to malaria susceptibility and rosetting have either used serological RBC agglutination assays to determine ABO blood group phenotype (A, B, AB, O), or single nucleotide polymorphisms (SNPs) at the ABO gene to derive ABO genotype (OO, AO, AA, BO, BB, AB), which have then been used to infer ABO phenotypes. This evidence concerns the gene ABO and malaria.