. DEFECTS OF ADAPTIVE IMMUNITY .
Hyper-IgM syndrome (HIGM) is a type of primary antibody deficiency characterized by the inability of B cells to switch from being IgM producing cells to being IgG, IgA, or IgE producing cells (class switch recombination deficiency). As a result, patients have decreased levels of immunoglobulin G (IgG) or IgA and normal to elevated levels of IgM in blood. Most of reported HIGM cases (70%) are caused by mutations in CD40LG, whereas the remaining 30% are caused by any of the other genes.
- Chronic bacterial Infections
- Elevated IgM in serum
- Lymphoid hyperplasia
- Onset: infancy and childhood, mostly boys
- 1:1,000,000 (AICDA deficiency)
- 70% (CD40LG)
Service benefits and management
- Differential diagnosis: CVID, agammaglobulinemia, CID
- Genetic counselling
- Ig replacement (IVIG)
- Antibiotic prophylaxis
- Avoid corticoids and live vaccines
AICDA, CD40, CD40LG, INO80, MSH6, PIK3R1, PMS2, UNG