Reassurance for Patients with Duffy-Null Associated Neutrophil Counts

A variant in the atypical chemokine receptor 1 (ACKR1) gene (rs2814778) associates with loss of the Duffy A and B antigens on red blood cell surfaces and lower white blood cell counts. This variant confers resistance to Plasmodium vivax malaria, accounting for high prevalence among persons with ancestry from malaria-endemic regions. Hematologists now classify a reduced leukocyte/neutrophil count in this setting as a “Duffy-null associated neutrophil count.” Referrals are still common given concern for primary marrow disorders or infectious complications. Further, patients with cancer and this variant can be excluded from clinical trials or receive unnecessary modifications to their chemotherapy regimens due to concerns presented by a lower …