Hyper IgM syndrome / CD40 Ligand deficiency
- Problem: Inability to produce specific antibodies (IgG, IgA, IgE);
deficiency in CD40 ligand causes miscommunication between B and T cell.
- T-cell disorder!!-T-cells unable to signal B cells to undergo isotype
switching from IgM to other classes; so IgM is the dominant antibody.
- Genetics: X-linked, Xq26
Presentation:
- Recurrent pyogenic sinopulmonary
infxns beginning in 1st or 2nd year of
life
- Lymphoid hyperplasia (as opposed
to XLA)
- Infections with Pneumocystis carinii; Pneumocystis jiroveci pneumonia
- Extensive verruca vulgaris lesions (bad warts)
Associations:
- Autoimmune disorders (very high)
- Hemolytic anemia
- Thrombocytopenia
- Transient, persistent, or cyclic neutropenia
Labs:
- Elevated
IgM
- Low
IgG and
IgA
- Normal number of B lymphocytes
CHLA board review 2005