Blood and immunity: selective IgA deficiency: 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 and immunity: selective IgA deficiency

Sample item

A woman with recurrent sinus infections and mild diarrhoea develops urticaria, wheeze and hypotension minutes into a blood transfusion. IgG and IgM are normal. Which finding best explains the reaction?

ASelective IgA deficiency, with anti-IgA antibodies reacting to donor IgABChronic granulomatous disease with defective killingCComplement C1 inhibitor deficiency, with unchecked bradykininDABO incompatibility between donor and recipient red cells

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

The answer and the reasoning

A. Selective IgA deficiency, with anti-IgA antibodies reacting to donor IgA

Selective IgA deficiency is the commonest primary antibody deficiency. Some patients form anti-IgA antibodies, which can cause anaphylaxis when donor plasma containing IgA is given. Washed red cells or IgA-deficient donor products are used in such patients.

Option by option

A. Selective IgA deficiency, with anti-IgA antibodies reacting to donor IgA (correct)
Correct. Anti-IgA antibodies react to IgA in donor plasma.
B. Chronic granulomatous disease with defective killing
Chronic granulomatous disease causes recurrent catalase-positive infections, not transfusion anaphylaxis.
C. Complement C1 inhibitor deficiency, with unchecked bradykinin
C1 inhibitor deficiency causes angioedema without urticaria or an IgA link.
D. ABO incompatibility between donor and recipient red cells
ABO incompatibility causes haemolysis with fever and flank pain rather than urticaria and wheeze.

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 A, Selective IgA deficiency, with anti-IgA antibodies reacting to donor IgA. Selective IgA deficiency is the commonest primary antibody deficiency.

Why is "Chronic granulomatous disease with defective killing" not the answer?

Chronic granulomatous disease causes recurrent catalase-positive infections, not transfusion anaphylaxis.

Why is "Complement C1 inhibitor deficiency, with unchecked bradykinin" not the answer?

C1 inhibitor deficiency causes angioedema without urticaria or an IgA link.

Why is "ABO incompatibility between donor and recipient red cells" not the answer?

ABO incompatibility causes haemolysis with fever and flank pain rather than urticaria and wheeze.

What concept does this question test?

It tests Blood and immunity: selective IgA deficiency in Physiology. Some patients form anti-IgA antibodies, which can cause anaphylaxis when donor plasma containing IgA is given. Washed red cells or IgA-deficient donor products are used in such patients.

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 Blood and immunity: selective IgA deficiency?

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.