ABSTRACT
Primary immune deficiency diseases (PIDDs) are genetic defects with distinct clinical phenotypes resulting in a broad range of susceptibility to infection, malignancy, allergy, and autoimmunity. Severe combined immune deficiencies (SCIDs) are the most severe forms of PIDD. The group includes a diversity of diseases caused by a variety of genetic defects. Their diagnosis, clinical presentations, and management are discussed. Predominantly, antibody deficiencies are the most clinically significant PIDDs, but this is also a heterogeneous group. Diagnosis and clinical presentation vary, but management primarily involves administration of intravenous immunoglobulin. The chapter includes discussions of diseases of immune dysregulation, some of which are associated with autoimmunity, congenital phagocytic defects, defects of intrinsic and innate immunity, including complement deficiencies, and the recently described phenocopies of PIDD.
