Respiratory: primary ciliary dyskinesia: 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 · Respiratory: primary ciliary dyskinesia

Sample item

A 24-year-old man has chronic productive cough since childhood, recurrent sinusitis and infertility with normal sperm counts but immotile sperm. Chest imaging shows bronchiectasis and the heart is on the right side. What is the underlying defect?

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

The answer and the reasoning

B. Absent or defective dynein arms in ciliary axonemes

Kartagener syndrome is a form of primary ciliary dyskinesia with situs inversus, sinusitis and bronchiectasis. Defective dynein arms prevent ciliary beating, so mucus is not cleared and embryonic organ rotation is randomised. Sperm flagella share the same axonemal structure, so sperm are immotile.

Option by option

  • A. Mutation in the CFTR chloride channel

    Cystic fibrosis also causes bronchiectasis but gives obstructive azoospermia and does not cause situs inversus.

  • B. Absent or defective dynein arms in ciliary axonemes (correct)

    Correct. Dynein arm defects explain bronchiectasis, immotile sperm and situs inversus.

  • C. Deficiency of alpha-1 antitrypsin

    Alpha-1 antitrypsin deficiency causes basal emphysema and liver disease, not immotile sperm.

  • D. Defective neutrophil NADPH oxidase

    Chronic granulomatous disease causes recurrent catalase-positive infections but not dextrocardia.

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 B, Absent or defective dynein arms in ciliary axonemes. Kartagener syndrome is a form of primary ciliary dyskinesia with situs inversus, sinusitis and bronchiectasis.

Why is "Mutation in the CFTR chloride channel" not the answer?

Cystic fibrosis also causes bronchiectasis but gives obstructive azoospermia and does not cause situs inversus.

Why is "Deficiency of alpha-1 antitrypsin" not the answer?

Alpha-1 antitrypsin deficiency causes basal emphysema and liver disease, not immotile sperm.

Why is "Defective neutrophil NADPH oxidase" not the answer?

Chronic granulomatous disease causes recurrent catalase-positive infections but not dextrocardia.

What concept does this question test?

It tests Respiratory: primary ciliary dyskinesia in Pathology. Defective dynein arms prevent ciliary beating, so mucus is not cleared and embryonic organ rotation is randomised. Sperm flagella share the same axonemal structure, so sperm are immotile.

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 Respiratory: primary ciliary dyskinesia?

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.