Metabolic: homocystinuria: 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.

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Pediatrics · Metabolic: homocystinuria

Sample item

A tall child with downward lens dislocation, intellectual disability and a history of thromboembolism has high urinary homocysteine. What is the first-line treatment trial?

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

The answer and the reasoning

B. Pyridoxine (vitamin B6)

Classical homocystinuria is cystathionine beta-synthase deficiency, and some patients respond to pyridoxine, with betaine and a methionine-restricted diet as adjuncts. Marfan-like habitus and downward ectopia lentis are typical. Thromboembolism is a major cause of morbidity.

Option by option

  • A. Vitamin K

    Vitamin K does not treat it.

  • B. Pyridoxine (vitamin B6) (correct)

    Correct. B6 is cofactor for the enzyme.

  • C. Vitamin C

    Vitamin C is not therapy for homocystinuria.

  • D. Biotin

    Biotin treats biotinidase and carboxylase deficiency.

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 Pediatrics question

What is the answer to this Pediatrics question?

The best answer is B, Pyridoxine (vitamin B6). Classical homocystinuria is cystathionine beta-synthase deficiency, and some patients respond to pyridoxine, with betaine and a methionine-restricted diet as adjuncts.

Why is "Vitamin K" not the answer?

Vitamin K does not treat it.

Why is "Vitamin C" not the answer?

Vitamin C is not therapy for homocystinuria.

Why is "Biotin" not the answer?

Biotin treats biotinidase and carboxylase deficiency.

What concept does this question test?

It tests Metabolic: homocystinuria in Pediatrics. Marfan-like habitus and downward ectopia lentis are typical. Thromboembolism is a major cause of morbidity.

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 Metabolic: homocystinuria?

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.