Duffy Antigen Status, Hydroxyurea Dosing, and Disease Severity in Children and Young Adults With Sickle Cell Disease

Most patients with sickle cell disease (SCD) also have the Duffy null red blood cell phenotype, often leading to lower absolute neutrophil counts (ANC). Hydroxyurea titration in SCD is largely driven by ANC. Hydroxyurea maximum tolerated dose (MTD) attainment, MTD dosage, and metrics of SCD severity based on both MTD attainment and Duffy antigen status were analyzed in pediatric and young adult patients. Rates of vasoocclusive episodes and emergency room visits for complications of SCD were increased in the total cohort of Duffy antigen positive patients and in Duffy antigen positive patients who attained MTD.