X-linked agammaglobulinemia (Bruton's disease)
Last reviewed: 23.04.2024
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X-linked agammaglobulinemia is characterized by a low level of immunoglobulins and antibodies or their absence, lack of B-lymphocytes, which is manifested by recurrent infections caused by encapsulated bacteria.
What causes X-linked agammaglobulinemia?
X-linked agammaglobulinemia is the result of a mutation in the X chromosome gene that codes for the Bruton tyrosine kinase (tkB, Btk - Bruton tyrosine kinase). TkB is very important for the development and maturation of B-lymphocytes; without it neither B-lymphocytes nor antibodies are formed. As a result, boys have very small tonsils and lymph nodes do not develop; the clinical picture is characterized by recurrent purulent infections of the lungs, paranasal sinuses, skin with encapsulated bacteria (Streptococcus pneumoniae, Hemophilus influenzae). There is a tendency to persistent infections of the CNS as a result of vaccination with a live oral polio vaccine, the viruses of Ekho and Coxsackie; these infections can manifest as progressive dermatomyositis, accompanied by or without encephalitis.
Diagnosis of X-linked agammaglobulinemia
The diagnosis is based on a low IgG level (<100 mg / dl) and the absence of B-lymphocytes (<1% of CD19 + cells established by flow cytometry). Transient neutropenia can also be observed. If there is an identical disease in family members, for the purpose of prenatal diagnosis, chorionic villus analysis, amniocentesis or cord blood sampling is performed.
[How is X-linked agammaglobulinemia treated?
Treatment consists in intravenous administration of immunoglobulin 400 mg / kg / month. Important is the appointment of adequate antibiotic therapy for each infectious process; with bronchiectasis, a long-term treatment with a change of antibiotics is necessary. In the case of early diagnosis and appropriate treatment, the prognosis is favorable, if viral infections of the central nervous system do not develop.