Molecular biology and genetics: JAK2 V617F mutation: 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 · Molecular biology and genetics: JAK2 V617F mutation

Sample item

A 55-year-old man has a raised haemoglobin, itching after a hot bath and splenomegaly. Bone marrow shows panmyelosis. A somatic mutation in which gene is found in most such patients?

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

The answer and the reasoning

A. JAK2 (V617F)

The JAK2 V617F mutation causes constitutive tyrosine kinase activity, making erythropoietin-receptor signalling independent of ligand. It is found in almost all cases of polycythaemia vera and in about half of essential thrombocythaemia and primary myelofibrosis. Ruxolitinib is a JAK inhibitor used in treatment.

Option by option

  • A. JAK2 (V617F) (correct)

    Correct. JAK2 V617F drives ligand-independent proliferation in polycythaemia vera.

  • B. RB1

    RB1 is a tumour suppressor mutated in retinoblastoma.

  • C. BCR-ABL1

    BCR-ABL1 defines chronic myeloid leukaemia, which usually gives leucocytosis rather than isolated erythrocytosis.

  • D. KIT

    KIT mutations are found in mastocytosis and gastrointestinal stromal tumours.

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 A, JAK2 (V617F). The JAK2 V617F mutation causes constitutive tyrosine kinase activity, making erythropoietin-receptor signalling independent of ligand.

Why is "RB1" not the answer?

RB1 is a tumour suppressor mutated in retinoblastoma.

Why is "BCR-ABL1" not the answer?

BCR-ABL1 defines chronic myeloid leukaemia, which usually gives leucocytosis rather than isolated erythrocytosis.

Why is "KIT" not the answer?

KIT mutations are found in mastocytosis and gastrointestinal stromal tumours.

What concept does this question test?

It tests Molecular biology and genetics: JAK2 V617F mutation in Biochemistry. It is found in almost all cases of polycythaemia vera and in about half of essential thrombocythaemia and primary myelofibrosis. Ruxolitinib is a JAK inhibitor used in treatment.

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 Molecular biology and genetics: JAK2 V617F mutation?

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.