Recent advances in the pathogenesis and treatment of nonimmune neutropenias in the neonate.

Neutropenia in the neonate is defined as a significantly lower than normal concentration of neutrophils in the peripheral blood and can be broadly classified as immune or nonimmune. Nonimmune neutropenias are those that are not the direct or indirect result of antibodies directed against neutrophils. Recent advances have been made in the pathogenesis and treatment of several types of neonatal neutropenia, including reticular dysgenesis, Schwachman-Diamond syndrome, Kostmann syndrome, neutropenia in infants of hypertensive women, and "idiopathic neutropenia." This review of nonimmune neutropenias highlights these developments.