Immunopathology: autoimmune lymphoproliferative syndrome: practice question

A Pathology question in the style of the NEET PG paper. Answer it first, then read why the right option is right and why each of the others is wrong.

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Pathology · Immunopathology: autoimmune lymphoproliferative syndrome

Sample item

A 6-year-old has chronic non-malignant lymphadenopathy, splenomegaly and autoimmune haemolytic anaemia. Lymphocytes are resistant to apoptosis, and double-negative T cells are increased. Which defect is most likely?

Original practice item, not a recalled exam question. Nothing here is recorded.

The answer and the reasoning

D. Mutation of FAS, impairing lymphocyte apoptosis

Fas-Fasl signalling normally deletes activated lymphocytes (activation-induced cell death). FAS mutation leads to failure of peripheral tolerance and lymphocyte accumulation, with autoimmune cytopenias, lymphadenopathy and an increased risk of lymphoma.

Option by option

  • A. Mutation of AIRE, impairing thymic selection

    AIRE affects central tolerance and gives endocrine autoimmunity.

  • B. Mutation of BTK, impairing B-cell maturation

    BTK deficiency gives agammaglobulinaemia and infections.

  • C. Mutation of CD40 ligand, impairing class switching

    CD40 ligand deficiency gives hyper-IgM and opportunistic infections.

  • D. Mutation of FAS, impairing lymphocyte apoptosis (correct)

    Correct. A defective Fas death receptor lets autoreactive lymphocytes survive.

Source note: Original NextPrep sample item — pending expert review. This item is original practice material awaiting independent expert review, so confirm important facts in a standard textbook.

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Questions about this Pathology question

What is the answer to this Pathology question?

The best answer is D, Mutation of FAS, impairing lymphocyte apoptosis. Fas-Fasl signalling normally deletes activated lymphocytes (activation-induced cell death).

Why is "Mutation of AIRE, impairing thymic selection" not the answer?

AIRE affects central tolerance and gives endocrine autoimmunity.

Why is "Mutation of BTK, impairing B-cell maturation" not the answer?

BTK deficiency gives agammaglobulinaemia and infections.

Why is "Mutation of CD40 ligand, impairing class switching" not the answer?

CD40 ligand deficiency gives hyper-IgM and opportunistic infections.

What concept does this question test?

It tests Immunopathology: autoimmune lymphoproliferative syndrome in Pathology. FAS mutation leads to failure of peripheral tolerance and lymphocyte accumulation, with autoimmune cytopenias, lymphadenopathy and an increased risk of lymphoma.

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. The tag is our own editorial judgement, not an official difficulty rating, so read the reason for every option, not only the answer.

How should I study Immunopathology: autoimmune lymphoproliferative syndrome?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology questions on this site to test what stuck.

Is this a real NEET PG question?

No. It is an original practice item (editorial status: sample, version 1). NextPrep does not publish recalled or leaked questions, and independent faculty review of this item has not been completed yet, so confirm important facts in a standard textbook.