Genetic and metabolic disorders: achondroplasia: 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.

Try it

Pediatrics · Genetic and metabolic disorders: achondroplasia

Sample item

A child has macrocephaly, frontal bossing, rhizomelic limb shortening, trident hands and normal intelligence, born to average-sized parents. Which gene is mutated?

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

The answer and the reasoning

D. FGFR3 activating mutation

Achondroplasia is autosomal dominant but most cases are new mutations in FGFR3 which inhibits endochondral growth. Features are rhizomelic shortening, trident hand and normal intelligence.

Option by option

  • A. COL1A1

    COL1A1 mutations cause osteogenesis imperfecta.

  • B. SHOX deletion

    SHOX deletion causes Turner or Leri-Weill features.

  • C. FBN1

    FBN1 mutations cause Marfan syndrome.

  • D. FGFR3 activating mutation (correct)

    Correct. FGFR3 is the gene.

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.

More Pediatrics questions

Questions about this Pediatrics question

What is the answer to this Pediatrics question?

The best answer is D, FGFR3 activating mutation. Achondroplasia is autosomal dominant but most cases are new mutations in FGFR3 which inhibits endochondral growth.

Why is "COL1A1" not the answer?

COL1A1 mutations cause osteogenesis imperfecta.

Why is "SHOX deletion" not the answer?

SHOX deletion causes Turner or Leri-Weill features.

Why is "FBN1" not the answer?

FBN1 mutations cause Marfan syndrome.

What concept does this question test?

It tests Genetic and metabolic disorders: achondroplasia in Pediatrics. Features are rhizomelic shortening, trident hand and normal intelligence.

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 Genetic and metabolic disorders: achondroplasia?

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.