Those who are Duffy-negative, estimated to be two out of three people identifying as Black in the U.S., lack Duffy antigens on the surface of their red blood cells as a mechanism to resist malaria. This helps provide protection but also disrupts the body’s chemical signaling to keep neutrophils — a type of white blood cell — in blood vessels. As a result, Duffy-negative blood samples can appear to have a dangerously low white blood cell count, though those cells reside in other parts of the body.
Under current blood cell ranges, Duffy-negative people are often misdiagnosed with neutropenia, leading to unnecessary medical procedures, exclusion from clinical trials and undue stress. To amend the ranges, the study team will collect and test blood samples for Duffy status, and assess the normal neutrophil count for the population group.
“In the future, if we see a blood sample with a low neutrophil count, we should test it for Duffy status,” Mei said. “If the sample is Duffy-negative, we should apply the appropriate reference range for that patient.”