MPN Voice
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Which is worse - Jak2 positive or Jak2 negative?

I personally have Jak2 negative with my ET. Platelets remaining stable around 350. Fatigue and Fuzzy head comes and goes randomly! I have recently increased my exercise routine to include cardio/strength exercises with help from a personal trainer. Although very demanding I am now beginning to feel better for the more intense exercise!

Kind regards


5 Replies


I am not sure there is an answer out there.

Have you been tested for the CALR mutation? thats common amongst those JAK2 negative folk.

Even the experts may struggle to advise, especially as its still quite early since these mutations were discovered.

People who are JAK2 negative can find JAK inhibitors like Ruxolitinib work for them so its certainly not black and white.

I think down the line the treatment you receive may well be dependant on what the cause (if its known) of your MPN is, but think we may be some way off that.



Im Jak 2 negative as well and am struggling more these days with tiredness than i did before. I now have blood out more often but according to my consultant it may have been too much this time hence why I'm so knackered this month.

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Hi Michael,

As Paul has said it's still early days for knowing what the significance is of the different gene mutations. I tested negative for JAK2 but then was tested for CALR when that first came out and it was positive, which is quite common if you're JAK2 negative - but then some people have neither mutation.

Some research suggests CALR positive ET may progress more slowly and have lower chance of turning to MF but no doubt more will emerge as the research into our conditions continues.

Exercise is definitely beneficial to your overall feeling of wellbeing so good to persevere with that..!

Good luck


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Hi all. , I am jak2 + and i was told it means i have a mutation in my bone marrow so i think the test was for a more difinative diagnosis for my mpn , and not just but increased plaltelet count alone , My local hospital at to send this test for jak 2 to London hospital its a specialised diagnosis i was told ! and i havent had yet had to have a bmb unless bloods change , im on clopidrel and HU daily with 10 weeks check up regards Holly


Hi retromickey, if I have done this correctly the above link is quite helpful. It is from the American society of haematology (hopefully).

Mary x

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