Haematology: Glanzmann thrombasthenia: 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 · Haematology: Glanzmann thrombasthenia

Sample item

A 7-year-old boy of consanguineous parents has recurrent epistaxis and gum bleeding. Platelet count and smear are normal and bleeding time is prolonged. Platelet aggregation is absent with ADP, collagen and epinephrine but normal with ristocetin. What is the defect?

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

The answer and the reasoning

D. Deficiency of the GPIIb/IIIa fibrinogen receptor on platelets

Glanzmann thrombasthenia is an autosomal recessive disorder in which GPIIb/IIIa (integrin alpha-IIb beta-3) is absent or dysfunctional, so fibrinogen cannot bridge platelets and aggregation fails. Ristocetin-induced agglutination depends on GPIb and von Willebrand factor, and so remains normal. The platelet count and morphology are normal.

Option by option

  • A. Deficiency of platelet dense granules

    Dense granule deficiency gives a storage pool defect with defective secondary aggregation, not complete absence with all agonists.

  • B. Deficiency of von Willebrand factor in plasma

    Von Willebrand deficiency gives reduced ristocetin response, which is normal here.

  • C. Deficiency of GPIb on platelets

    GPIb deficiency is Bernard-Soulier syndrome, with giant platelets and absent ristocetin response.

  • D. Deficiency of the GPIIb/IIIa fibrinogen receptor on platelets (correct)

    Correct. Absent fibrinogen receptors cause failure of aggregation to all physiological agonists but normal ristocetin response.

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, Deficiency of the GPIIb/IIIa fibrinogen receptor on platelets. Glanzmann thrombasthenia is an autosomal recessive disorder in which GPIIb/IIIa (integrin alpha-IIb beta-3) is absent or dysfunctional, so fibrinogen cannot bridge platelets and aggregation fails.

Why is "Deficiency of platelet dense granules" not the answer?

Dense granule deficiency gives a storage pool defect with defective secondary aggregation, not complete absence with all agonists.

Why is "Deficiency of von Willebrand factor in plasma" not the answer?

Von Willebrand deficiency gives reduced ristocetin response, which is normal here.

Why is "Deficiency of GPIb on platelets" not the answer?

GPIb deficiency is Bernard-Soulier syndrome, with giant platelets and absent ristocetin response.

What concept does this question test?

It tests Haematology: Glanzmann thrombasthenia in Pathology. Ristocetin-induced agglutination depends on GPIb and von Willebrand factor, and so remains normal. The platelet count and morphology are normal.

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 Haematology: Glanzmann thrombasthenia?

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.