Genetics: Marfan syndrome: practice question

A Pediatrics 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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Pediatrics · Genetics: Marfan syndrome

Sample item

A tall adolescent with arachnodactyly, upward lens dislocation and mitral valve prolapse has a family history of aortic dissection. What is the defective protein?

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

The answer and the reasoning

C. Fibrillin-1

Marfan syndrome is autosomal dominant with FBN1 mutations, giving ectopia lentis (usually upward), aortic root dilatation and skeletal overgrowth. Echocardiography and beta-blockers or losartan slow aortic dilatation. Homocystinuria has downward lens displacement.

Option by option

  • A. Collagen type I

    Collagen I defect causes osteogenesis imperfecta.

  • B. Dystrophin

    Dystrophin defect causes Duchenne dystrophy.

  • C. Fibrillin-1 (correct)

    Correct. Fibrillin-1 is defective.

  • D. Elastin

    Elastin defect causes Williams syndrome and cutis laxa.

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 Pediatrics question

What is the answer to this Pediatrics question?

The best answer is C, Fibrillin-1. Marfan syndrome is autosomal dominant with FBN1 mutations, giving ectopia lentis (usually upward), aortic root dilatation and skeletal overgrowth.

Why is "Collagen type I" not the answer?

Collagen I defect causes osteogenesis imperfecta.

Why is "Dystrophin" not the answer?

Dystrophin defect causes Duchenne dystrophy.

Why is "Elastin" not the answer?

Elastin defect causes Williams syndrome and cutis laxa.

What concept does this question test?

It tests Genetics: Marfan syndrome in Pediatrics. Echocardiography and beta-blockers or losartan slow aortic dilatation. Homocystinuria has downward lens displacement.

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 Genetics: Marfan syndrome?

Memorise milestones and the vaccine schedule as tables and revise them often. Then use the flashcards and the other Pediatrics 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.