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OVERVIEW
Hyper IgM syndrome refers to genetic condition that is characterized by the overproduction of IgM antibodies, as well the deficiency of other antibody classes.
WHAT CAUSES IT?
An X-linked genetic defect in the CD40 ligand is responsible for this condition. This ligand is responsible for mediation the class switching of B-cells, so in the absence of its proper function, B-cells are unable to class switch and continue only producing IgM antibodies.
WHY IS THIS A PROBLEM?
The inability to class switch results in increased IgM levels, and deficiencies of other antibody types. This class switching is an important element of the immune response, and in its absence, the host is susceptible to infections.
WHAT MAKES US SUSPECT IT?
Initial Presentation
- Recurrent infections in young children: acute otitis media, sinusitis, pneumonia
CLINICAL WORKUP
Serum studies:
- IgG levels: these will be decreased
- IgA levels: these will be decreased
- IgM levels: these will be increased
ARCHIVE OF STANDARDIZED EXAM QUESTIONS
This archive compiles standardized exam questions that relate to this topic.
Page Updated: 11.25.2016