Antibody-predominant immunodeficiencies vs Combined T-cell or cytoskeletal immunodeficiencies
How to tell Antibody-predominant immunodeficiencies and Combined T-cell or cytoskeletal immunodeficiencies apart when a board question makes them look alike.
Bruton is absent B cells; Hyper-IgM is class-switch failure; SCID is combined severe T/B dysfunction; Wiskott-Aldrich is eczema plus infections plus small-platelet thrombocytopenia.
Side by side
Bruton agammaglobulinemia has absent mature B cells and all immunoglobulins after maternal IgG wanes; Hyper-IgM has failed class switching with high IgM and low IgG/IgA/IgE.
SCID causes severe combined T- and B-cell dysfunction with early viral, fungal, and opportunistic infections; Wiskott-Aldrich has eczema, recurrent infections, and thrombocytopenia with small platelets.
BTK mutation blocks B-cell maturation in Bruton; CD40L or class-switch defects prevent immunoglobulin class switching in Hyper-IgM.
SCID disrupts lymphocyte development or signaling; X-linked Wiskott-Aldrich syndrome reflects a WASP cytoskeletal defect that impairs immune-cell actin dynamics and platelet formation.
Low all immunoglobulins with absent B cells supports Bruton; high IgM with low class-switched immunoglobulins supports Hyper-IgM.
Low T cells with severe opportunistic infections supports SCID; thrombocytopenia with small platelets and eczema supports Wiskott-Aldrich.
The trap
Recurrent infections overlap, so age, immunoglobulin pattern, T-cell status, and platelet clues separate them.
The repair move
For primary immunodeficiency, sort antibody pattern, T-cell function, and platelet/eczema clues.
Try a free question
CoreA male infant develops recurrent bacterial sinus and lung infections after 6 months of age. Tonsils are absent, mature B cells are absent, and IgG, IgA, IgM, and IgE are all very low. Which diagnosis is most likely?
Show answer and explanation
Answer: A. Bruton agammaglobulinemia. Absent mature B cells with low all immunoglobulins after maternal IgG wanes points to Bruton agammaglobulinemia.
Why the other choices are tempting
- B. Hyper-IgM has high IgM with low class-switched immunoglobulins.
- C. SCID causes severe combined T- and B-cell dysfunction with opportunistic infections early.
- D. Wiskott-Aldrich has eczema and small-platelet thrombocytopenia.
- E. Selective IgA deficiency has isolated low IgA with otherwise preserved B cells.
Flashcards
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What pattern points to Bruton agammaglobulinemia?
Absent mature B cells with low all immunoglobulins after maternal IgG wanes points to Bruton agammaglobulinemia.
What pattern points to Hyper-IgM syndrome?
High IgM with low IgG, IgA, and IgE points to class-switch failure in Hyper-IgM syndrome.
Quick answers
What is the fastest way to tell Antibody-predominant immunodeficiencies from Combined T-cell or cytoskeletal immunodeficiencies?
Bruton is absent B cells; Hyper-IgM is class-switch failure; SCID is combined severe T/B dysfunction; Wiskott-Aldrich is eczema plus infections plus small-platelet thrombocytopenia.
What is the key clue for Antibody-predominant immunodeficiencies?
Bruton agammaglobulinemia has absent mature B cells and all immunoglobulins after maternal IgG wanes; Hyper-IgM has failed class switching with high IgM and low IgG/IgA/IgE.
What is the key clue for Combined T-cell or cytoskeletal immunodeficiencies?
SCID causes severe combined T- and B-cell dysfunction with early viral, fungal, and opportunistic infections; Wiskott-Aldrich has eczema, recurrent infections, and thrombocytopenia with small platelets.
What is the common trap with Antibody-predominant immunodeficiencies vs Combined T-cell or cytoskeletal immunodeficiencies?
Recurrent infections overlap, so age, immunoglobulin pattern, T-cell status, and platelet clues separate them.