Primary immunodeficiency states

The primary immunodeficiency states 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.

Only some of the more recognized ones are listed below.

Disorders of adaptive immunity
T-cell (cellular) immunodeficiency
  • IFN-γ/IL-12
  • AIRE mutations
  • chronic mucocutaneous candidiasis
  • selective T-cell functional defects
B-cell (antibody-mediated) immunodeficiency
  • common variable immunodeficiency
  • specific antibody deficiency
  • IgG subclass deficiency
    • selective IgG deficiency
  • common variable hypogammaglobulinemia
  • IgA deficiency - considered most common
    • selective IgA deficiency
  • X-linked hypogammaglobulinemia
  • panhypogammaglobulinemia (ring 18 chromosome)
Combined immunodeficiency
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
Others