Intermediate
Technical
IVT
immunoglobulin subclass deficiency
Selective reduction in specific IgG subclasses while total IgG levels remain normal, causing recurrent infections in children.
Full Definition
A primary immunodeficiency characterized by decreased levels of one or more IgG subclasses (IgG1, IgG2, IgG3, or IgG4) despite normal total immunoglobulin G concentrations. In pediatric practice, IgG2 and IgG3 subclass deficiencies are most clinically significant, often presenting with recurrent sinopulmonary infections and poor responses to polysaccharide vaccines. This condition requires specialized laboratory testing as standard immunoglobulin quantification may appear normal.
Usage
Usage note: Specify which subclass when possible (e.g., 'IgG2 subclass deficiency' rather than generic 'subclass deficiency').
In Context
- "The child's recurrent pneumonia was attributed to IgG2 subclass deficiency despite normal total IgG levels." — immunology consultation
- "Immunoglobulin subclass deficiency should be considered in patients with poor vaccine responses to pneumococcal polysaccharides." — diagnostic guidelines
Also known as
IgG subclass deficiency
selective IgG deficiency
Contrasted with
normal immunoglobulin levels
Don't confuse with
hypogammaglobulinemia
selective IgA deficiency