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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