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How Common is the Duffy Null Polymorphism Among Children With Sickle Cell Disease? Does It Affect Treatment?

How Common is the Duffy Null Polymorphism Among Children With Sickle Cell Disease? Does It Affect Treatment? 1024 683 Pam Georgiana

Recent research shows that a commonly inherited polymorphism could impact outcomes.

At a recent hematology team meeting, Susan E. Creary, MD, and colleagues found themselves discussing the Duffy null, a common genetic condition in which the Duffy antigen is not found on red blood cells, might affect children with sickle cell disease. This is because their neutrophil counts can be lower in their bloodstream. The neutrophils tend to stay in their tissues rather than float in their blood.

“The American Society of Hematology has been focusing on Duffy null because it leads to lower neutrophil counts in patients, but doesn’t increase their risk of infection,” says Dr. Creary a pediatric hematologist in the division of Hematology, Oncology, & Blood and Marrow Transplant (BMT) and a principal investigator in the Center for Child Health Equity and Outcomes Research at Nationwide Children’s Hospital. “This is important because we use neutrophil counts to determine when and how much  chemotherapy and other treatments to provide, including the primary treatment for sickle cell disease, hydroxyurea.”

Patients are typically monitored closely while taking hydroxyurea, with regular blood tests to monitor neutrophil counts, assess the medication’s effectiveness, and detect adverse effects. Based on these monitoring results, dosing adjustments may be made.

Emerging data has shown that Duffy null is prevalent in people of African ancestry. One recent study found that 66.7% (80 of 120) of Black individuals had the Duffy null phenotype and that there was a significant difference in neutrophil counts between Duffy null and Duffy non-null individuals.

Dr. Creary, who studies the optimization of pediatric therapies for children with sickle cell disease, and her research team wondered if Duffy null would be prevalent in a contemporary cohort of sickle cell patients in the Midwest and what its potential impact would be on their hydroxyurea dosing and outcomes during their first year of use. To investigate this, they conducted a retrospective study of 187 Nationwide Children’s patients from 2010 to 2022. The study involved determining how many had Duffy null and comparing the neutrophil counts of those with Duffy null to those without Duffy null. They also compared the neutrophil counts, hydroxyurea dosing, and outcomes of those on hydroxyurea who did and did not have Duffy null. The results of this comprehensive study were recently published in Pediatric Blood Cancer.

Almost 80% of the children with sickle cell disease had the Duffy null polymorphism. However, there was no association between having Duffy null and the hydroxyurea dose a patient received or the number of acute visits during the first year of treatment when compared to patients who didn’t have Duffy null.

It’s important to note that the cohort’s average age was two years old. Since sickle cell disease  tends to worsen with age, further research is needed to confirm these results in a larger, older, and more diverse patient population.

“While these results were reassuring that Duffy null does not have a large impact early in the treatment course, sickle cell can become particularly challenging and damaging in the teen years. So, we need more research to confirm our findings and to evaluate the impact of Duffy null on neutrophil counts and ongoing hydroxyurea treatment as these children get older,” Dr. Creary says.

For patients with sickle cell disease, hydroxyurea therapy typically continues throughout their life. Thus, it’s critical that doctors understand how Duffy null may affect the efficacy of this life-extending drug.

“My biggest takeaways from this study are that Duffy null is quite common among people with sickle cell disease and health care providers should consider how other genetic markers, like Duffy null, may also affect our patients so that we are able to provide effective and a personalized treatment,” Dr. Creary says. “By tailoring our therapies to individual genetic details such as Duffy null, we may be able to significantly enhance treatment outcomes.”

 

References:

  1. Merz LE, Story CM, Osei MA, Jolley K, Ren S, Park HS, Freedman RY, Neuberg D, Smeland-Wagman R, Kaufman RM, Achebe MO. Absolute neutrophil count by Duffy status among healthy Black and African American adults. Blood Advances. 2023;7(3):317-320.
  2. Oladipupo F, Stanek J, Walden J, Young J, Rose MJ, Nicol K, Villella A, Creary S. Prevalence of Duffy null and its impact on hydroxyurea in young children with sickle cell disease in the United States. Pediatric Blood & Cancer. 2024;71(6):e30945.

About the author

Pam Georgiana is a brand marketing professional and writer located in Bexley, Ohio. She believes that words bind us together as humans and that the best stories remind us of our humanity. She specialized in telling engaging stories for healthcare, B2B services, and nonprofits using classic storytelling techniques. Pam has earned an MBA in Marketing from Capital University in Columbus, Ohio.

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