Blood: haemoglobin variants: practice question

A Physiology 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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Physiology · Blood: haemoglobin variants

Sample item

A 24-year-old woman has haemoglobin 10.4 g/dL, MCV 62 fL, red cell count 5.8 million per microlitre and a normal serum ferritin. Her mother has similar findings. High-performance liquid chromatography is most likely to show which result?

AHaemoglobin H inclusions with absent haemoglobin ABHaemoglobin S at 40%CHaemoglobin F as the only haemoglobinDRaised haemoglobin A2, above 3.5%

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

The answer and the reasoning

D. Raised haemoglobin A2, above 3.5%

Marked microcytosis with a high red cell count and normal iron stores points to thalassaemia trait. Haemoglobin A2 is composed of alpha and delta chains; in beta-thalassaemia trait reduced beta chain output leaves relatively more delta chains, so haemoglobin A2 rises above 3.5%. This is the confirmatory test.

Option by option

A. Haemoglobin H inclusions with absent haemoglobin A
Haemoglobin H disease is an alpha-thalassaemia state with moderate to severe anaemia and haemoglobin A present.
B. Haemoglobin S at 40%
Haemoglobin S indicates sickle cell trait, which has normal red cell indices.
C. Haemoglobin F as the only haemoglobin
Haemoglobin F alone would imply severe beta-thalassaemia major with transfusion dependence, not mild anaemia.
D. Raised haemoglobin A2, above 3.5% (correct)
Correct. A raised haemoglobin A2 level confirms beta-thalassaemia trait.

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.

Questions about this Physiology question

What is the answer to this Physiology question?

The best answer is D, Raised haemoglobin A2, above 3.5%. Marked microcytosis with a high red cell count and normal iron stores points to thalassaemia trait.

Why is "Haemoglobin H inclusions with absent haemoglobin A" not the answer?

Haemoglobin H disease is an alpha-thalassaemia state with moderate to severe anaemia and haemoglobin A present.

Why is "Haemoglobin S at 40%" not the answer?

Haemoglobin S indicates sickle cell trait, which has normal red cell indices.

Why is "Haemoglobin F as the only haemoglobin" not the answer?

Haemoglobin F alone would imply severe beta-thalassaemia major with transfusion dependence, not mild anaemia.

What concept does this question test?

It tests Blood: haemoglobin variants in Physiology. Haemoglobin A2 is composed of alpha and delta chains; in beta-thalassaemia trait reduced beta chain output leaves relatively more delta chains, so haemoglobin A2 rises above 3.5%. This is the confirmatory test.

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 Blood: haemoglobin variants?

For each system, sketch the key graph (pressure–volume loop, oxygen dissociation curve, nephron handling) and explain it aloud. Then use the flashcards and the other Physiology 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.