MPN Voice
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Clarify jargon please

As I am recently diagnosed, reading the posts is quite an education. It will help with my first hematology appointment later this week. (Yes I am an American so for me  it is hemo- not heamo-)

But... can someone tell me what JAK2+ means?  My primary care physician told me I have the JAK2 gene. I have also read that here is a mutation of JAK2.  Also that not all ET patients have JAK2.  So my question is: Does JAK2+ mean the gene is present or does it mean the mutated gene is present?

5 Replies

JAK2+ means the mutated gene is present.

But that's only a part of the story so have a good chat with your hemo and don't jump to any conclusions.

Best regards


JAk 2+  indicates that the gene is mutated. Anyone correct me if I'm  wrong. When it is mutated it is causes bone marrow on overdrive producing to many platelets.  My research says that the mutation is caused by exposure to ionizing radiation and trauma.  I am jak 2 positive and I take x-rays and do cat scans for a living. I also wrecked my motorcycle about the time I was diagnosed with ET JAK2+.  JAK 2 gene was discovered in 2005. 

Maybe this helps. I also live in the states but we do share this common disorder with folks around the world. 


Hello Eileen, this might help:

JAK2 V617F – some have it, some don’t

About 97% of people who have polycythaemia vera have the JAK2V617F mutation, while just 50-60% of people with essential thrombocythaemia or myelofibrosis have the mutation.

We don’’t know why some people who have an MPN have the mutation, and others don’t but it may be that there are other mutations that occur earlier in the process of disease development, and that we haven’t discovered those mutations yet. The most recent research appears to indicate that the JAK2 mutation is a middle step in the development of myeloproliferative neoplasms. 


Also  here in the US, ET JAk2+ diagnosed  7 mos ago. 


Thanks for the responses. I guess I am a bit of a nerd re understanding the medical details. In my early career I was a clinical lab tech and my last working period was in the biotechnology industry, specifically genetic analysis. So specifics of interest to me may not be of interest to others (boring, perhaps?). 

After writing my post I did some research.  I learned:  JAK2 is shorthand for a normal enzyme called Janus kinase 2.  JAK2 is not a gene!  The enzyme's job in the body is to cause blood cell production in bone marrow. Normally it is turned on and off by genetic control that is usually responding to the need/no need for more cells. The mutation called JAK2V617F (and it seems other yet-to -be determined factors) changes the genetic control to always be "on", causing sustained JAK2 stimulation of blood cells. The genetic turn "off" ability is lost.

So that's my long way of getting to understand that the JAK2+ diagnostic shorthand I've seen here means I have the JAK2V617F genetic mutation. I have it about right?


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