Immunodeficiency Disorders

Abstract

1. Ivan K. Chinn, MD*,† 2. Jordan S. Orange, MD, PhD‡,§ 1. *Department of Pediatrics, Section of Immunology, Allergy, and Rheumatology, Baylor College of Medicine, Houston, TX 2. †Center for Human Immunobiology, Texas Children’s Hospital, Houston, TX 3. ‡Department of Pediatrics, Columbia University College of Physicians and Surgeons, New York, NY 4. §New York Presbyterian Morgan Stanley Children’s Hospital, New York, NY * Abbreviations: ALC absolute lymphocyte count: : ALPS autoimmune lymphoproliferative syndrome CGD chronic granulomatous disease: : HIV human immunodeficiency virus HLH hemophagocytic lymphohistiocytosis: : Ig immunoglobulin PID primary immunodeficiency: : SCID severe combined immunodeficiency disease SLE systemic lupus erythematosus: : TLR toll-like receptor Immunodeficiencies are no longer considered rare conditions. Although susceptibility to infections has become well-recognized as a sign of most primary immunodeficiencies, some children will present with noninfectious manifestations that remain underappreciated and warrant evaluation by an immunologic specialist. Providers must also consider common secondary causes of immunodeficiency in children. After completing this article, readers should be able to: 1. Recognize infectious signs and symptoms of primary immunodeficiency that warrant screening and referral to a specialist. 2. Understand noninfectious signs and symptoms that should raise concern for primary immunodeficiency. 3. Determine appropriate testing for patients for whom immunodeficiency is suspected. 4. Discuss the management of patients with primary immunodeficiency. 5. Appreciate secondary causes of immunodeficiency. Immunodeficiency disorders represent defects in the immune system that result in weakened or dysregulated immune defense. These deficiencies may occur as primary diseases or secondary conditions. This article reviews primary and secondary immunodeficiencies, with particular emphasis on the evaluation and management of children with primary immunodeficiencies (PIDs). PIDs constitute inherent defects in immunity, most of which arise from inborn deviations in the genetic code. More than 300 PIDs have been identified. These conditions have been placed into 9 categories corresponding with their clinical and immunologic phenotypes by an international group of experts who evaluate these diseases every 2 years (Table 1). (1) Although PIDs were previously believed to represent rare conditions, they are now known to affect 1 of every 1,200 to …