Genetic and metabolic disorders: hereditary tyrosinaemia type 1: 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 · Genetic and metabolic disorders: hereditary tyrosinaemia type 1

Sample item

A 5-month-old has hepatomegaly, failure to thrive, a coagulopathy not corrected by vitamin K, renal tubular dysfunction with rickets and a boiled-cabbage odour. Which treatment improves outcome?

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

The answer and the reasoning

C. Nitisinone plus a restricted diet

Tyrosinaemia type 1 is fumarylacetoacetate hydrolase deficiency, with toxic succinylacetone causing liver failure, tubular dysfunction and hepatocellular carcinoma risk. Nitisinone blocks the upstream enzyme and, with dietary restriction, prevents the toxic metabolites. Urine succinylacetone confirms the diagnosis.

Option by option

  • A. Sodium benzoate and a low-protein diet

    Sodium benzoate lowers ammonia in urea cycle defects, which do not cause this tubular disease.

  • B. L-carnitine supplementation

    Carnitine helps fatty acid oxidation and organic acid disorders, not tyrosinaemia.

  • C. Nitisinone plus a restricted diet (correct)

    Correct. Nitisinone plus dietary restriction prevents accumulation of toxic metabolites.

  • D. A galactose-free formula

    A galactose-free diet treats galactosaemia, which has cataracts and E. coli sepsis.

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 C, Nitisinone plus a restricted diet. Tyrosinaemia type 1 is fumarylacetoacetate hydrolase deficiency, with toxic succinylacetone causing liver failure, tubular dysfunction and hepatocellular carcinoma risk.

Why is "Sodium benzoate and a low-protein diet" not the answer?

Sodium benzoate lowers ammonia in urea cycle defects, which do not cause this tubular disease.

Why is "L-carnitine supplementation" not the answer?

Carnitine helps fatty acid oxidation and organic acid disorders, not tyrosinaemia.

Why is "A galactose-free formula" not the answer?

A galactose-free diet treats galactosaemia, which has cataracts and E. coli sepsis.

What concept does this question test?

It tests Genetic and metabolic disorders: hereditary tyrosinaemia type 1 in Pediatrics. Nitisinone blocks the upstream enzyme and, with dietary restriction, prevents the toxic metabolites. Urine succinylacetone confirms the diagnosis.

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 Genetic and metabolic disorders: hereditary tyrosinaemia type 1?

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.