Nucleotide metabolism: allopurinol hypersensitivity: practice question

A Biochemistry 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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Biochemistry · Nucleotide metabolism: allopurinol hypersensitivity

Sample item

A man of Han Chinese descent develops a widespread blistering rash with mucosal ulceration four weeks after starting allopurinol. Which allele is known to predispose to this reaction?

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

The answer and the reasoning

B. HLA-B*58:01

HLA-B*58:01 carriage strongly predisposes to severe cutaneous adverse reactions to allopurinol, including Stevens-Johnson syndrome and toxic epidermal necrolysis, particularly in people of Han Chinese, Thai and Korean ancestry. Screening may be considered before starting therapy.

Option by option

  • A. HLA-B*15:02

    HLA-B*15:02 is linked to carbamazepine skin reactions in Asian patients.

  • B. HLA-B*58:01 (correct)

    Correct. HLA-B*58:01 is linked to allopurinol hypersensitivity.

  • C. HLA-B*27

    HLA-B*27 is linked to ankylosing spondylitis, not to a drug reaction.

  • D. HLA-B*57:01

    HLA-B*57:01 is linked to abacavir hypersensitivity.

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 Biochemistry question

What is the answer to this Biochemistry question?

The best answer is B, HLA-B*58:01. HLA-B*58:01 carriage strongly predisposes to severe cutaneous adverse reactions to allopurinol, including Stevens-Johnson syndrome and toxic epidermal necrolysis, particularly in people of Han Chinese, Thai and Korean ancestry.

Why is "HLA-B*15:02" not the answer?

HLA-B*15:02 is linked to carbamazepine skin reactions in Asian patients.

Why is "HLA-B*27" not the answer?

HLA-B*27 is linked to ankylosing spondylitis, not to a drug reaction.

Why is "HLA-B*57:01" not the answer?

HLA-B*57:01 is linked to abacavir hypersensitivity.

What concept does this question test?

It tests Nucleotide metabolism: allopurinol hypersensitivity in Biochemistry. Screening may be considered before starting therapy.

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 Nucleotide metabolism: allopurinol hypersensitivity?

Build one table of enzyme deficiency, disease, inheritance and key finding, then revise it by spaced recall. Then use the flashcards and the other Biochemistry 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.