Collagen: Ehlers-Danlos syndrome: practice question

A Biochemistry 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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Biochemistry · Collagen: Ehlers-Danlos syndrome

Sample item

A 28-year-old woman has thin translucent skin with visible veins, easy bruising and a spontaneous sigmoid colon perforation. Her brother died of a ruptured aneurysm at 30. Which protein is defective?

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

The answer and the reasoning

C. Type III collagen

Vascular Ehlers-Danlos syndrome results from COL3A1 mutations affecting type III collagen, the main collagen of vessel walls, hollow organs and skin. This causes arterial, bowel and uterine rupture. Type I defects cause osteogenesis imperfecta.

Option by option

  • A. Type I collagen

    Type I collagen defects produce brittle bones and blue sclerae.

  • B. Type II collagen

    Type II collagen is cartilage collagen, and its defects cause chondrodysplasias.

  • C. Type III collagen (correct)

    Correct. Type III collagen gives strength to arteries and hollow viscera.

  • D. Type IV collagen

    Type IV collagen forms basement membranes, and its defect causes Alport syndrome.

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 Biochemistry question

What is the answer to this Biochemistry question?

The best answer is C, Type III collagen. Vascular Ehlers-Danlos syndrome results from COL3A1 mutations affecting type III collagen, the main collagen of vessel walls, hollow organs and skin.

Why is "Type I collagen" not the answer?

Type I collagen defects produce brittle bones and blue sclerae.

Why is "Type II collagen" not the answer?

Type II collagen is cartilage collagen, and its defects cause chondrodysplasias.

Why is "Type IV collagen" not the answer?

Type IV collagen forms basement membranes, and its defect causes Alport syndrome.

What concept does this question test?

It tests Collagen: Ehlers-Danlos syndrome in Biochemistry. This causes arterial, bowel and uterine rupture. Type I defects cause osteogenesis imperfecta.

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 Collagen: Ehlers-Danlos syndrome?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry 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.