Medical genetics: Duchenne and Becker muscular dystrophy: practice question

A Anatomy 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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Anatomy · Medical genetics: Duchenne and Becker muscular dystrophy

Sample item

Duchenne and Becker muscular dystrophy both arise from deletions in the dystrophin gene on Xp21, yet Duchenne is much more severe. What explains the difference?

ADuchenne is autosomal recessive and Becker is X-linkedBDuchenne arises from a trinucleotide repeat expansionCFrameshift deletions abolish dystrophin, while in-frame ones leave a partial proteinDBecker mutations involve a different gene on chromosome 4

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

The answer and the reasoning

C. Frameshift deletions abolish dystrophin, while in-frame ones leave a partial protein

Dystrophin is X-linked recessive. Deletions that shift the reading frame produce a premature stop codon and absent protein (Duchenne), whereas in-frame deletions yield a shortened but partly functional protein (Becker).

Option by option

A. Duchenne is autosomal recessive and Becker is X-linked
Both conditions are X-linked recessive.
B. Duchenne arises from a trinucleotide repeat expansion
Both are caused by deletions or point mutations rather than by repeat expansion.
C. Frameshift deletions abolish dystrophin, while in-frame ones leave a partial protein (correct)
Correct. The reading-frame rule explains the severity difference.
D. Becker mutations involve a different gene on chromosome 4
Both are caused by the same gene on Xp21.

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.

Questions about this Anatomy question

What is the answer to this Anatomy question?

The best answer is C, Frameshift deletions abolish dystrophin, while in-frame ones leave a partial protein. Dystrophin is X-linked recessive.

Why is "Duchenne is autosomal recessive and Becker is X-linked" not the answer?

Both conditions are X-linked recessive.

Why is "Duchenne arises from a trinucleotide repeat expansion" not the answer?

Both are caused by deletions or point mutations rather than by repeat expansion.

Why is "Becker mutations involve a different gene on chromosome 4" not the answer?

Both are caused by the same gene on Xp21.

What concept does this question test?

It tests Medical genetics: Duchenne and Becker muscular dystrophy in Anatomy. Deletions that shift the reading frame produce a premature stop codon and absent protein (Duchenne), whereas in-frame deletions yield a shortened but partly functional protein (Becker).

How hard is this question?

We tag it as a multi-step question: it asks you to combine more than one idea. 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 Medical genetics: Duchenne and Becker muscular dystrophy?

Learn every nerve by its route, its muscles and what a lesion looks like at the bedside. That one habit answers a large share of questions. Then use the flashcards and the other Anatomy 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.