Vesiculobullous disorders: epidermolysis bullosa simplex with muscular dystrophy: practice question

A Dermatology 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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Dermatology · Vesiculobullous disorders: epidermolysis bullosa simplex with muscular dystrophy

Sample item

A child has blistering of the skin from friction since infancy and later develops progressive muscle weakness. Biopsy shows a split within the basal keratinocytes. A mutation in which gene is responsible?

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

The answer and the reasoning

A. PLEC, encoding plectin

Plectin links intermediate filaments to hemidesmosomes in the basal cell and is also expressed in muscle. PLEC mutations cause epidermolysis bullosa simplex with muscular dystrophy, so a basal-layer split plus myopathy suggests this subtype.

Option by option

  • A. PLEC, encoding plectin (correct)

    Correct. Plectin mutations cause basal-layer EB simplex with muscular dystrophy.

  • B. COL7A1, encoding type VII collagen

    COL7A1 mutations cause dystrophic EB with a split below the lamina densa.

  • C. LAMB3, encoding laminin 332

    LAMB3 mutations cause junctional EB with a split in the lamina lucida.

  • D. KRT1, encoding keratin 1

    KRT1 mutations cause epidermolytic hyperkeratosis, with suprabasal blistering and thick scale.

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 Dermatology question

What is the answer to this Dermatology question?

The best answer is A, PLEC, encoding plectin. Plectin links intermediate filaments to hemidesmosomes in the basal cell and is also expressed in muscle.

Why is "COL7A1, encoding type VII collagen" not the answer?

COL7A1 mutations cause dystrophic EB with a split below the lamina densa.

Why is "LAMB3, encoding laminin 332" not the answer?

LAMB3 mutations cause junctional EB with a split in the lamina lucida.

Why is "KRT1, encoding keratin 1" not the answer?

KRT1 mutations cause epidermolytic hyperkeratosis, with suprabasal blistering and thick scale.

What concept does this question test?

It tests Vesiculobullous disorders: epidermolysis bullosa simplex with muscular dystrophy in Dermatology. PLEC mutations cause epidermolysis bullosa simplex with muscular dystrophy, so a basal-layer split plus myopathy suggests this subtype.

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 Vesiculobullous disorders: epidermolysis bullosa simplex with muscular dystrophy?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.