Embryology: warfarin embryopathy: 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 · Embryology: warfarin embryopathy

Sample item

A baby born to a mother who took warfarin in the first trimester has nasal hypoplasia and stippled epiphyses on X-ray. Which mechanism explains the bone changes?

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

The answer and the reasoning

B. Inhibition of vitamin K dependent carboxylation of proteins in cartilage and bone

Warfarin crosses the placenta and blocks the vitamin K dependent gamma-carboxylation of proteins such as osteocalcin. This leads to abnormal calcification, nasal hypoplasia and chondrodysplasia punctata.

Option by option

  • A. Excess retinoic acid altering Hox gene expression

    Retinoids cause craniofacial, cardiac and thymic defects.

  • B. Inhibition of vitamin K dependent carboxylation of proteins in cartilage and bone (correct)

    Correct. Reduced carboxylation of bone matrix proteins causes abnormal calcification and stippling.

  • C. Inhibition of fetal thyroid hormone synthesis

    Thyroid blockade by antithyroid drugs causes goitre and hypothyroidism.

  • D. Folate antagonism interfering with neural tube closure

    Folate antagonists cause neural tube defects and cleft palate rather than stippled epiphyses.

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 Anatomy question

What is the answer to this Anatomy question?

The best answer is B, Inhibition of vitamin K dependent carboxylation of proteins in cartilage and bone. Warfarin crosses the placenta and blocks the vitamin K dependent gamma-carboxylation of proteins such as osteocalcin.

Why is "Excess retinoic acid altering Hox gene expression" not the answer?

Retinoids cause craniofacial, cardiac and thymic defects.

Why is "Inhibition of fetal thyroid hormone synthesis" not the answer?

Thyroid blockade by antithyroid drugs causes goitre and hypothyroidism.

Why is "Folate antagonism interfering with neural tube closure" not the answer?

Folate antagonists cause neural tube defects and cleft palate rather than stippled epiphyses.

What concept does this question test?

It tests Embryology: warfarin embryopathy in Anatomy. This leads to abnormal calcification, nasal hypoplasia and chondrodysplasia punctata.

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 Embryology: warfarin embryopathy?

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.