Prevalence of Ethnic Neutropenia and Duffy Null Phenotype in Neonates

This is a prospective observational study designed to assess the prevalence of the Duffy null phenotype (associated with ethnic neutropenia) in neonates born at Kaplan Medical Center. Blood samples will be collected from umbilical cords (non-invasively) to evaluate Duffy antigen expression. Data on ethnicity, perinatal factors, and routine blood counts at 9-12 months (when available) will also be collected to correlate phenotype with absolute neutrophil count (ANC).