Prevalence of Ethnic Neutropenia and Duffy Null Phenotype in Neonates

This is a prospective, observational cohort study designed to evaluate the prevalence of the Duffy null phenotype (Fya-/Fyb-) and its association with ethnic neutropenia in neonates born at Kaplan Medical Center in Israel. The Duffy null phenotype has been linked to lower peripheral neutrophil counts without increased infection risk in certain ethnic groups, a condition commonly referred to as benign ethnic neutropenia. Cord blood samples will be collected from approximately 1,000 neonates during routine G6PD testing. An additional 3 mL will be obtained non-invasively from the umbilical cord after labour to determine the expression of Duffy antigens using serologic gel testing. Parental consent will be obtained, and information regarding ethnicity and family history of neutropenia will be collected. Participants identified with the Duffy null phenotype will be followed through electronic health records to assess their neutrophil counts during routine blood screening at 9-12 months of age. The study will analyze associations between Duffy phenotype, neutropenia prevalence, and parental ethnic origin. Findings may support improved diagnostic clarity around neonatal neutropenia and help reduce unnecessary interventions in otherwise healthy infants with genetically determined low neutrophil counts.