People who do not express ACKR1 protein on the surface of red blood cells, due to a homozygous variant in the ACKR1 gene (Duffy-null), are associated with a lower-than-average blood neutrophil count (shown in the right-hand panel). This is due to altered chemokine signalling, which is mediated by the ACKR1 protein and leads to abnormal neutrophil migration. By contrast, people who express ACKR1 protein on the surface of red blood cells (Duffy-positive) do not have altered ACKR1-chemokine signalling, and therefore, have normal neutrophil migration between blood and tissues (shown in the left-hand panel).
