Systemic pathology: achondroplasia: practice question

A Pathology 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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Pathology · Systemic pathology: achondroplasia

Sample item

A child has short limbs with a normal-sized trunk and frontal bossing. The condition results from a gain-of-function mutation in FGFR3. Which process is primarily disturbed?

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

The answer and the reasoning

D. Endochondral ossification at the growth plate

Achondroplasia is caused by activating FGFR3 mutations that inhibit chondrocyte proliferation in the growth plate, so endochondral bone growth is reduced, shortening the long bones. Intramembranous ossification is normal, so the skull vault and clavicles are spared.

Option by option

  • A. Osteoclast bone resorption

    Defective osteoclast function causes osteopetrosis, with dense brittle bone.

  • B. Intramembranous ossification of the skull vault

    Intramembranous ossification is preserved in achondroplasia.

  • C. Synthesis of type I collagen

    Defective type I collagen synthesis causes osteogenesis imperfecta, with fractures and blue sclerae.

  • D. Endochondral ossification at the growth plate (correct)

    Correct. Excess FGFR3 signalling slows proliferation of growth plate chondrocytes.

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 Pathology question

What is the answer to this Pathology question?

The best answer is D, Endochondral ossification at the growth plate. Achondroplasia is caused by activating FGFR3 mutations that inhibit chondrocyte proliferation in the growth plate, so endochondral bone growth is reduced, shortening the long bones.

Why is "Osteoclast bone resorption" not the answer?

Defective osteoclast function causes osteopetrosis, with dense brittle bone.

Why is "Intramembranous ossification of the skull vault" not the answer?

Intramembranous ossification is preserved in achondroplasia.

Why is "Synthesis of type I collagen" not the answer?

Defective type I collagen synthesis causes osteogenesis imperfecta, with fractures and blue sclerae.

What concept does this question test?

It tests Systemic pathology: achondroplasia in Pathology. Intramembranous ossification is normal, so the skull vault and clavicles are spared.

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 Systemic pathology: achondroplasia?

Learn each disease as a bundle: cause, key histology, markers, and the clinical hallmark. Then use the flashcards and the other Pathology 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.