Pigmentary disorders: albinism: practice question

A Dermatology 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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Dermatology · Pigmentary disorders: albinism

Sample item

A child has white hair, pink skin, nystagmus and photophobia, with a normal number of melanocytes. Which enzyme defect underlies the commonest type, OCA1?

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

The answer and the reasoning

A. Tyrosinase

Oculocutaneous albinism type 1 results from mutations in the TYR gene encoding tyrosinase, which blocks melanin synthesis in otherwise normal melanocytes. Patients need strict photoprotection and ophthalmic care.

Option by option

  • A. Tyrosinase (correct)

    Correct. Tyrosinase deficiency causes OCA1.

  • B. Homogentisate oxidase

    Homogentisate oxidase deficiency causes alkaptonuria.

  • C. Phenylalanine hydroxylase

    Phenylalanine hydroxylase deficiency causes phenylketonuria.

  • D. Fumarylacetoacetase

    Fumarylacetoacetase deficiency causes tyrosinaemia type 1.

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 Dermatology question

What is the answer to this Dermatology question?

The best answer is A, Tyrosinase. Oculocutaneous albinism type 1 results from mutations in the TYR gene encoding tyrosinase, which blocks melanin synthesis in otherwise normal melanocytes.

Why is "Homogentisate oxidase" not the answer?

Homogentisate oxidase deficiency causes alkaptonuria.

Why is "Phenylalanine hydroxylase" not the answer?

Phenylalanine hydroxylase deficiency causes phenylketonuria.

Why is "Fumarylacetoacetase" not the answer?

Fumarylacetoacetase deficiency causes tyrosinaemia type 1.

What concept does this question test?

It tests Pigmentary disorders: albinism in Dermatology. Patients need strict photoprotection and ophthalmic care.

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 Pigmentary disorders: albinism?

Learn each condition by its primary lesion, site and signature sign. Then use the flashcards and the other Dermatology 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.