Neutropenia and primary immunodeficiency diseases.

Primary immunodeficiency diseases (PID) are a heterogeneous group of congenital disorders of the immune system leading to recurrent infections, autoimmunity, malignancies, and hematological disorders. This review focuses specifically on inherited disorders associated with neutropenia, which may occur in isolation or as a feature of more complex immune disorders. It has been known for a long time that defined immunodeficiency syndromes, such as CD40L deficiency, WHIM syndrome, or Chédiak Higashi syndrome, may be associated with neutropenia even though the mechanisms are poorly understood. In some PID, neutropenia may result from chronic viral infection or from autoimmunity. Recently, the identification of several novel genetic defects (e.g., p14-deficiency, HAX1-deficiency, AK2-deficiency) has shed light on the pathophysiology of congenital neutropenia. This review summarizes the clinical, immunological, and genetic features of congenital neutropenia syndromes.