Paediatric: Duchenne muscular dystrophy: practice question

A Orthopaedics 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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Orthopaedics · Paediatric: Duchenne muscular dystrophy

Sample item

A 5-year-old boy uses his hands to climb up his thighs when rising from the floor and has enlarged calves. Which gene is affected?

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

The answer and the reasoning

A. Dystrophin gene on the X chromosome

Duchenne muscular dystrophy is an X-linked recessive disorder from mutation of the dystrophin gene at Xp21. Features are Gowers sign, calf pseudohypertrophy and markedly raised creatine kinase. Corticosteroids slow the progress.

Option by option

  • A. Dystrophin gene on the X chromosome (correct)

    Correct. Dystrophin deficiency causes DMD.

  • B. PMP22 gene

    PMP22 duplication causes Charcot-Marie-Tooth type 1A.

  • C. FMR1 gene

    FMR1 expansion causes fragile X syndrome.

  • D. SMN1 gene on chromosome 5

    SMN1 mutation causes spinal muscular atrophy.

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 Orthopaedics question

What is the answer to this Orthopaedics question?

The best answer is A, Dystrophin gene on the X chromosome. Duchenne muscular dystrophy is an X-linked recessive disorder from mutation of the dystrophin gene at Xp21.

Why is "PMP22 gene" not the answer?

PMP22 duplication causes Charcot-Marie-Tooth type 1A.

Why is "FMR1 gene" not the answer?

FMR1 expansion causes fragile X syndrome.

Why is "SMN1 gene on chromosome 5" not the answer?

SMN1 mutation causes spinal muscular atrophy.

What concept does this question test?

It tests Paediatric: Duchenne muscular dystrophy in Orthopaedics. Features are Gowers sign, calf pseudohypertrophy and markedly raised creatine kinase. Corticosteroids slow the progress.

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 Paediatric: Duchenne muscular dystrophy?

Pair each fracture with its classic complication and nerve injured. Then use the flashcards and the other Orthopaedics 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.