Neonatal alloimmune neutropenia (NAIN) is a transient disorder characterised by maternal IgG antibodies targeting fetal neutrophil antigens, resulting in neutropenia. This condition arises when the fetus inherits neutrophil-specific antigens from the father that are absent in the mother. Maternal sensitisation leads to the production of alloantibodies, which cross the placenta and mediate neutrophil destruction.
