Genetic and metabolic disorders: Hunter syndrome: 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: Hunter syndrome

Sample item

A 4-year-old boy has coarse facies, hepatosplenomegaly, aggressive behaviour and no corneal clouding. His maternal uncle had a similar illness. Which enzyme is deficient?

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

The answer and the reasoning

A. Iduronate sulphatase

Hunter syndrome (MPS II) is X-linked recessive and, unlike Hurler syndrome, has clear corneas. Iduronate sulphatase deficiency causes accumulation of heparan and dermatan sulphates. Hurler syndrome is autosomal recessive with corneal clouding.

Option by option

  • A. Iduronate sulphatase (correct)

    Correct. X-linked inheritance without corneal clouding indicates iduronate sulphatase deficiency.

  • B. Heparan N-sulphatase

    Heparan N-sulphatase deficiency causes Sanfilippo syndrome with behavioural problems but little coarse facies.

  • C. Galactosamine-6-sulphatase

    Galactosamine-6-sulphatase deficiency causes Morquio syndrome with skeletal dysplasia.

  • D. Alpha-L-iduronidase

    Alpha-L-iduronidase deficiency is Hurler syndrome with corneal clouding.

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 A, Iduronate sulphatase. Hunter syndrome (MPS II) is X-linked recessive and, unlike Hurler syndrome, has clear corneas.

Why is "Heparan N-sulphatase" not the answer?

Heparan N-sulphatase deficiency causes Sanfilippo syndrome with behavioural problems but little coarse facies.

Why is "Galactosamine-6-sulphatase" not the answer?

Galactosamine-6-sulphatase deficiency causes Morquio syndrome with skeletal dysplasia.

Why is "Alpha-L-iduronidase" not the answer?

Alpha-L-iduronidase deficiency is Hurler syndrome with corneal clouding.

What concept does this question test?

It tests Genetic and metabolic disorders: Hunter syndrome in Pediatrics. Iduronate sulphatase deficiency causes accumulation of heparan and dermatan sulphates. Hurler syndrome is autosomal recessive with corneal clouding.

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: Hunter syndrome?

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.