A Simple Pathway to Identify Duffy-Null Associated Neutrophil Count (DANC) Early on Hematology Consult Process

Introduction: The normal range for neutrophil counts in individuals with Duffy-null RBCs is often lower than commonly used laboratory reference ranges. This is a genetically determined baseline neutrophil count. The Duffy-null phenotype is caused by a variant in the ACKR1 promoter that results in loss of expression of Duffy antigens (Fy) on RBCs.

Method: Primary care submits electronic consults for patient who have white blood cell count below the laboratory normal range. The hematology service consultant recommends peripheral blood smear review, differential count, B12, folate, copper, HIV screen and HCV screen the last two according to CDC guidelines. The hospital blood bank committee created a process that include the routine type and screen with a comment that Duffy a and Duffy b report required.

Results: Forty-five patients have been tested on this pathway from November 2023 to July 2024 because the hematologist suspected DANC, from those 43 had the confirmation of Fy(a) and Fy(b) negative. Two were Fy(a) negative but Fy(b) positive. All had normal B12, folate, copper, negative HIV, and hepatitis c screening. On the referral for those patients, several have been told that they were being referred for possible myelodysplastic syndrome and for bone marrow biopsy. Once the test results were available, the patients who wanted to have a meeting to discuss the results were either scheduled on a clinic with medical students or residents with purpose of educating trainees and expand the knowledge of this normal variant. The individuals who wanted included their self-identified race. The incidence on different races were discussed only when the patients inquired.

Conclusion: This test is simple, produces rapid results, is relatively inexpensive and is easily incorporated on day-to-day practice. An education material was submitted to primary care providers, hematology fellows, residents, and students. Future direction is to develop education material for patients. Test consideration will be discussed at our center for patients who initiate chemotherapy with counts lower than the reference range or who have prolonged neutropenia during treatment to avoid unnecessarily holding therapy. Plan to develop studies and guidelines specific for patients with DANC based in developing literature.

No relevant conflicts of interest to declare.