X-linked agammaglobulinemia

X-linked agammaglobulinemia
Updated: 08/17/2020
© Jun Wang, MD, PhD

General features
  • AKA Bruton's disease
  • Impaired B cell differentiation and immunoglobulin production
  • X-linked
  • Almost exclusively in boys
Clinical presentations
  • Recurrent infections, especially encapsulated pyogenic bacteria, such as Streptococcus Pneumoniae
  • Commonly pneumonia, otitis media, diarrhea, etc
  • Presentations starts 4-6 months after birth
Genetic abnormality
  • Bruton tyrosine kinase mutation
Pathogenesis
  • B cell development arrest
Key Laboratory findings
  • Low levels of Ig after 6 months, IgM and IgA typically undetectable
  • Markedly reduced or absent CD19+ B cells in circulation
  • Circulating T cells may be increased
Key morphological features
  • Underdeveloped or absent lymphoid tissue, such as lymph nodes, tonsils, etc.
  • Absent plasma cells
Diagnosis
  • Low or absent number of mature B cells
  • Low or absent expression of m heavy chain on surface of lymphocytes
  • Molecular tests for absence of BTK RNA or protein
Managements
  • Immunoglobulin replacement
  • Treatments of infections



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