Neutropenia in primary immunodeficiency.

PURPOSE OF REVIEW: Neutropenia is a feature of several primary immunodeficiency diseases (PIDDs). Because of the diverse pathophysiologies of the PIDDs and the rarity of each disorder, data are often lacking, leading to the necessity of empiric treatment. Recent developments in the understanding of neutropenia in several of the PIDDs make a review of the data timely. RECENT FINDINGS: The category of severe congenital neutropenia continues to expand. Mutations in G6PC3 have been identified as the cause of neutropenia in a minority of previously molecularly undefined cases. Recent advances have broadened our understanding of the pathophysiology and the clinical expression of this disorder. A possible function of the C16orf57 gene has been hypothesized that may explain the clinical overlap between Clerucuzio-type poikiloderma with neutropenia and other marrow diseases. Plerixafor has been shown to be a potentially useful treatment in the warts, hypogammaglobulinemia, infection, and myelokathexis syndrome. Investigations of patients with adenosine deaminase deficient severe combined immunodeficiency have identified neutropenia, and particularly susceptibility to myelotoxins, as a feature of this disorder. Granulocyte-colony stimulating factor is the treatment of choice for neutropenia in PIDD, whereas hematopoietic cell transplantation is the only curative option. SUMMARY: The number of PIDDs associated with neutropenia has increased, as has our understanding of the range of phenotypes. Additional data and hypotheses have been generated helping to explain the diversity of presentations of neutropenia in PIDDs.