New blood count ranges could prevent unnecessary testing for people with Duffy-null trait

The American Society of Hematology has created new blood count ranges specifically for individuals with Duffy-null status, a genetic trait affecting over 66% of people with African or Mediterranean ancestry in the U.S. These personalized ranges will help doctors accurately differentiate between normal and abnormal white blood cell counts, avoiding unnecessary testing.

Under standard ranges, people with Duffy-null status might be incorrectly diagnosed with neutropenia, a condition linked to infection or illness, potentially leading to invasive procedures, clinical trial disqualifications, or medication suspensions. This development is particularly significant for those with Duffy-null status, who often face unnecessary medical evaluations and treatments.

The Duffy antigen, a protein on red blood cells, is absent in Duffy-null individuals, providing resistance to malaria parasites through a higher concentration of neutrophils in body tissues. When Duffy-null individuals undergo blood tests, their lower circulating neutrophil count can be misinterpreted as a sign of illness, such as infection or cancer.

Researchers from 23 U.S. sites collected data from 1,412 Duffy-null individuals to establish these new reference ranges, which have been published in Blood Advances. Although the findings are based on diverse collection methods and patient populations, no significant differences were found in the ranges when these factors were considered.

Further study is needed to determine ranges for children under 6 months old. Knowing one's Duffy status can empower patients to advocate for appropriate care throughout their healthcare journey, as this condition is not a disease but a genetic variant associated with lower white blood cell levels. The Society recommends discussing Duffy testing with healthcare providers and sharing results in medical records.

ASH also published a cost-effectiveness analysis demonstrating that universal pediatric testing for the Duffy-null variant benefits children's health.