Hyper IgM syndrome
Hyper IgM syndrome
Updated: 08/15/2022
© Jun Wang, MD, PhD
General features
- Commonly X-linked, may be autosomal recessive
- Commonly have positive family history of male lateral relatives
- Relatively poor prognosis
Clinical presentations
- Recurrent infections including pneumonia, and opportunistic pathogens, such as pneumocystis jiroveci etc
Genetic abnormalities
- Loss of function mutation of CD40 ligand on CD4+ T cells
- May be caused by CD40 deficiency on B cells
Pathogenesis
- Defective interaction between helper T cell and developing B cells/macrophages
- Impaired immunoglobulin isotype switch
- Impaired CD40L-mediated macrophage activation
Key Laboratory findings
- Neutropenia, probably due to myeloid maturation arrest
- High IgM
- Low IgA, IgG, and IgE
Diagnosis
- Male patient with serum IgG concentration at least 2 SD below normal for age and one of the following:
Mutation of CD40L
Maternal cousins, uncles, or nephews with
confirmed diagnosis of XHIM
Managements
- Immunoglobulin replacement
- Treatments of infections
- Granulocyte colony-stimulating factor
- Bone marrow transplantation, stem cell transplantation
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