Chapter 160: Primary Immune Deficiency Diseases

DEFINITION

Primary immunodeficiencies are genetic diseases that can involve all possible aspects of immune responses, from innate through adaptive, as well as cell differentiation, effector function, and immune regulation (Table 160-1). The consequences of primary immunodeficiencies vary widely as a function of the molecules that are defective and include vulnerability to infection by pathogenic and opportunistic infection, immunopathologic responses such as allergy, lymphoproliferations, and autoimmunity, and increased risk of cancers. The locations and sites of infection and the causal microorganisms often aid the physician in diagnosis.

TABLE 160-1: Classification of Primary Immune Deficiency Diseases
Deficiencies of the innate immune system
Phagocytic cells: Impaired production: severe congenital neutropenia (SCN) Asplenia Impaired adhesion: leukocyte adhesion deficiency (LAD) Impaired killing: chronic granulomatous disease (CGD) Innate immunity receptors and signal transduction: Defects in Toll-like receptor signaling Mendelian susceptibility to mycobacterial disease Complement deficiencies: Classical, alternative, and lectin pathways Lytic phase
Deficiencies of the adaptive immune system
T lymphocytes: Impaired development Impaired survival, migration, function	Severe combined immune deficiencies (SCIDs) DiGeorge’s syndrome Combined immunodeficiencies Hyper-IgE syndrome (autosomal dominant) DOCK8 deficiency CD40 ligand deficiency Wiskott-Aldrich syndrome Ataxia-telangiectasia and other DNA repair deficiencies
B lymphocytes: Impaired development Impaired function	XL and AR agammaglobulinemia Hyper-IgM syndrome Common variable immunodeficiency (CVID) IgA deficiency
Regulatory defects
Innate immunity Adaptive immunity	Autoinflammatory syndromes (outside the scope of this chapter) Severe colitis Hemophagocytic lymphohistiocytosis (HLH) Autoimmune lymphoproliferation syndrome (ALPS) Autoimmunity and inflammatory diseases (IPEX, APECED)

Abbreviations: APECED, autoimmune polyendocrinopathy candidiasis ectodermal dysplasia; AR, autosomal recessive; IPEX, immunodysregulation polyendocrinopathy enteropathy X-linked syndrome; XL, X-linked.

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