Apoptosis: extrinsic pathway: 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 · Apoptosis: extrinsic pathway

Sample item

A 6-year-old boy has persistent lymphadenopathy, splenomegaly and autoimmune haemolytic anaemia. Blood shows increased TCR alpha-beta T cells that express neither CD4 nor CD8 (double-negative T cells). Defective apoptosis through which receptor is the likely cause?

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

The answer and the reasoning

D. Fas (CD95) death receptor

Autoimmune lymphoproliferative syndrome results from mutations in FAS (or FAS ligand, or caspase 10), so activated lymphocytes escape death through the extrinsic pathway. Lymphocytes accumulate, producing nodes, splenomegaly and autoimmune cytopenias. Fas engagement normally recruits FADD and activates caspase 8.

Option by option

  • A. Perforin pore-forming protein

    Perforin deficiency causes familial haemophagocytic lymphohistiocytosis, with fever and cytopenias.

  • B. BCL-2 overexpression at the mitochondrial membrane

    BCL-2 overexpression blocks the intrinsic pathway and characterises follicular lymphoma, not this syndrome.

  • C. Autoimmune regulator (AIRE) transcription factor

    AIRE deficiency causes loss of central tolerance in APECED, with endocrine failure and candidiasis.

  • D. Fas (CD95) death receptor (correct)

    Correct. Failure of Fas-mediated apoptosis lets autoreactive lymphocytes persist.

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, Fas (CD95) death receptor. Autoimmune lymphoproliferative syndrome results from mutations in FAS (or FAS ligand, or caspase 10), so activated lymphocytes escape death through the extrinsic pathway.

Why is "Perforin pore-forming protein" not the answer?

Perforin deficiency causes familial haemophagocytic lymphohistiocytosis, with fever and cytopenias.

Why is "BCL-2 overexpression at the mitochondrial membrane" not the answer?

BCL-2 overexpression blocks the intrinsic pathway and characterises follicular lymphoma, not this syndrome.

Why is "Autoimmune regulator (AIRE) transcription factor" not the answer?

AIRE deficiency causes loss of central tolerance in APECED, with endocrine failure and candidiasis.

What concept does this question test?

It tests Apoptosis: extrinsic pathway in Pathology. Lymphocytes accumulate, producing nodes, splenomegaly and autoimmune cytopenias. Fas engagement normally recruits FADD and activates caspase 8.

How hard is this question?

We tag it as an application question: it asks you to use a fact on a patient or a finding. 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 Apoptosis: extrinsic pathway?

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.