X-linked (Bruton) agammaglobulinemia USMLE Step 1

XLA - X-linked (Bruton) agammaglobulinemia USMLE Step 1:
The X-linked recessive disorder occurs almost exclusively in males in X-chromosomes.
Caused by a defect in the BTK gene, which encodes for a tyrosine kinase essential for B-cell maturation and differentiation
Presents clinically with recurrent bacterial and enteroviral infections after 6 months of age, once maternal IgG levels have declined
In the absence of functional BTK, B cells fail to develop beyond the pre-B cell stage, leading to a complete absence of mature B cells in the peripheral blood and lymphoid tissues.
Lack of B cells also results in a severe deficiency of all classes of immunoglobulins.
Genetics and Pathophysiology
 The absence of functional B cells leads to a complete lack of immunoglobulins of all classes

Due to the lack of protective immunity, live vaccines are contraindicated in individuals with X-linked (Bruton) agammaglobulinemia

Streptococcus pneumoniae, Hemophilus influenzae, Streptoccocus pyogenes, and Pseudomonas

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