The primary immunodeficiency diseases are a heterogenous group of disorders that occur when there is an impairment of humoral or cell-mediated immunity in the absence of any recognized precipitating cause such as drug therapy or infective agent such as human immunodeficiency virus (HIV).
Epidemiology
The majority are diagnosed in children under the age of one, although milder forms may not be recognized until adulthood.
Classification
They are broadly classified as disorders of adaptive immunity (i.e. T-cell, B-cell or combined immunodeficiencies) or of innate immunity (i.e. phagocyte and complement disorders). Over 260 conditions may exist 3.
Only some of the more recognized ones are listed below.
Disorders of adaptive immunity
T-cell (cellular) immunodeficiency
IFN-γ/IL-12
AIRE mutations
B-cell (antibody-mediated) immunodeficiency
specific antibody deficiency
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IgG subclass deficiency
-
IgA deficiency - considered most common 2
selective IgA deficiency
panhypogammaglobulinemia (ring 18 chromosome)
Combined immunodeficiency
-
T- , B+
γc deficiency
JAK3 deficiency
-
T- , B-
ADA deficiency
RAG 1/2 deficiency
Disorders of innate immunity
Phagocyte defects
Complement defects
deficiency in early complement pathway components (C1q, C1r, C2, C4)
deficiency in late complement pathway components (C5, C6, C7, C8, C9)
C3 and regulatory components