Antibodies to human neutrophil antigen HNA‐4b implicated in a case of neonatal alloimmune neutropenia

BACKGROUND Maternal alloantibodies directed against human neutrophil antigens (HNAs) can cause moderate‐severe neutropenia in the newborn in a condition known as neonatal alloimmune neutropenia (NAIN). Neonates with NAIN can present with sepsis or be asymptomatic. NAIN has previously been reported as caused by antibodies against HNA‐1a, ‐1b, and ‐1c; CD16b, ‐2, ‐3a, ‐4a, and ‐5a; and HLA, but not by antibodies against HNA‐4b. We report a case of...