Tag Archive for: JAK2

What Is a JAK2 Mutation?

Editor’s Note: This resource, What is a JAK2 Mutation?, was originally published by MyHealthTeam.

One of the most commonly mutated proteins found in myeloproliferative neoplasms (MPNs) is the protein Janus kinase 2 (JAK2). This important discovery has changed how doctors diagnose and treat people with MPNs. We will be discussing both the JAK protein and the JAK gene.

MPNs are blood cancers caused by the overproduction of blood cells in the bone marrow. Mutations in the gene controlling JAK2 protein production occur most often in the three classic types of MPNs:

The V617F mutation in the JAK2 gene is found in:

  • 96 percent of polycythemia vera cases
  • 50 percent to 60 percent of primary myelofibrosis cases
  • 50 percent to 60 percent of essential thrombocythemia cases

Additionally, more than 50 different JAK2 mutations have been found in other parts of the JAK2 gene, primarily in PV cases.

What Is the JAK2 Gene?

The JAK2 protein plays an important role in controlling the production of blood cells from stem cells found in the bone marrow.

The JAK2 gene is responsible for genetically coding the JAK2 protein. This protein is part of the JAK/STAT pathway, which transmits signals to promote cell growth.

When the JAK2 protein is activated, it relays a signal to the protein STAT, which then binds to another STAT molecule in a process called dimerization. This group of molecules then moves into the cell’s nucleus, turning on genes that tell the cell to grow and proliferate.

What Causes JAK2 Mutations?

There are two main types of JAK2 mutations found in MPNs.

V617F Mutation

The V617F mutation is caused by a change in a single base in the genetic code. This simple change then switches the amino acid valine (V) to phenylalanine (F) at position 617 in the JAK2 protein, changing the shape of the protein. When this mutation is present, JAK2 signaling is turned on and cannot be turned off, leading to uncontrolled cell growth. In the case of MPNs, this causes an overproduction of blood cells, leading to blood cancers.

Multiple Mutations

Many different types of mutations can be found within multiple parts of the JAK2 gene. More than 50 different mutations have been identified in the gene, and almost all of these occur in people with PV.

One part of the JAK2 gene is particularly susceptible to mutations. This area genetically codes for a linker that connects two parts of the JAK2 protein. Common mutations here include deletions and insertions. A deletion is when entire pieces of the protein are lost. Insertions occur when incorrect pieces are put into the protein. Insertions and deletions change the shape of the JAK2 protein, which can affect its function.

Do JAK2 Mutations Cause MPNs?

MPNs are caused by a mutation in a single stem cell found in the bone marrow. These mutations cause the cell to rapidly divide, creating too many of one cell type. JAK2 gene mutations are involved in many cases of MPNs. In addition to JAK2 genesmutations found in CALR and MPL genes are also common contributors to the development of MPNs. These three mutations are usually mutually exclusive, meaning that if one mutation is present, then the others are not.

JAK2 Mutations and MPN Diagnosis and Prognosis

A number of tests are required to diagnose MPNs, each providing a different piece of information. The doctor will begin with a physical examination and health history. They may also order a complete blood count (CBC) with a differential, which assesses the number of red blood cells, platelets, and white blood cells.

Because most MPNs are associated with a specific genetic mutation, a pathologist may use blood samples to test for these. Two tests used to identify genetic abnormalities are quantitative polymerase chain reaction (qPCR) and fluorescent in situ hybridization (FISH). Typically, only one of the two tests is required for diagnosis. It is also an option to perform DNA sequencing to identify the driving mutation in an MPN case.

Quantitative Polymerase Chain Reaction

Quantitative polymerase chain reaction (qPCR) is the most commonly used method for diagnosing JAK2 mutations. qPCR is also the most sensitive test, and it can detect small amounts of mutation when other methods fail.

With qPCR, DNA obtained from a blood test is mixed with a fluorescent dye, which is run through a machine that amplifies the sequences containing the JAK2 mutation.

Fluorescent In Situ Hybridization

This test determines whether someone has chromosomal abnormalities contributing to a cancerous phenotype. For example, one type of MPN, chronic myeloid leukemia (CML), is characterized by the presence of a Philadelphia chromosome (named for where it was discovered). A Philadelphia chromosome forms when two pieces of broken chromosomes stick together. This is also called the BCR-ABL1 gene, because one broken piece contains the BCR gene, and the other contains the ABL1 gene.

Most people with MPNs who are Philadelphia chromosome-negative (Ph-) have the V617F mutation in JAK2. This important discovery revealed the driving mutation behind Ph- MPNs. Before the discovery of JAK2 mutation, the cause of these defects was unknown. This also led to the development of specific JAK2 inhibitors for treatment of myeloproliferative disorders.

In 2016, the World Health Organization (WHO) revised its document “WHO Classification of Tumours of Haematopoietic and Lymphoid Tissues.” This revision included new criteria for diagnosing MPNs by the three main driver mutations in JAK2, CALR, and MPL genes. PV is characterized by the presence of a JAK2 mutation. ET and MF are characterized by the presence of any of the three driver mutations.

JAK2 Mutations and MPN Treatments

Since the discovery of JAK2 mutations in MPNs, researchers have developed a number of inhibitors targeting the protein. There are currently two JAK2 inhibitors approved by the U.S. Food and Drug Administration (FDA) for the treatment of MPNs:


Jakafi (ruxolitinib) is approved for treatment of MF hydroxyurea-resistant PV. It is also being investigated for use in people with hydroxyurea-resistant ET. Additionally, some trials are investigating the effects of Jakafi in combination with the antimetabolite chemotherapies Vidaza (azacitidine) and Dacogen (decitabine). Antimetabolites are a special type of cancer drug that interfere with DNA by acting as a substitute for the normal building blocks of DNA.


Approved in 2019, Inrebic (fedratinib) is the newest MPN drug in almost a decade. It’s used to treat three forms: high-risk MF, post-polycythemia vera MF, and post-essential thrombocythemia MF with splenomegaly (enlarged spleen).

Other JAK2 inhibitors are currently in phase 3 clinical trials, including Pacritinib for the treatment of MF and severe thrombocytopenia, and Momelotinib for the treatment of MF. These promising new drugs are in final phases of testing.

Overall, the discovery of JAK2 mutations in MPNs has helped advance drug research, development, and MPN treatment. It has also helped combat uncontrolled proliferation of blood cells, improving the lives of people with MPNs. New medications continue to be developed and tested, providing a hopeful future for those affected by myeloproliferative diseases.

Finding Support With an MPN

You are not alone living with an MPN. When you join myMPNteam, you gain a community of others who know what it’s like to face a rare blood cancer diagnosis.

Do you know whether your MPN has tested positive for a JAK mutation? Did your doctor explain what the results of the test mean for your condition? Share your experiences on myMPNteam.

What Is Next Generation Sequencing for MPNs?

What Is Next Generation Sequencing for MPNs? from Patient Empowerment Network on Vimeo.

Myeloproliferative neoplasm (MPN) care may include the use of next generation sequencing.  Dr. Kristen Pettit from Rogel Cancer Center explains next generation sequencing and how it is used in MPN patient care.

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Dr. Kristen Pettit:

Next generation sequencing or NGS refers to tests done from the blood or the bone marrow that can look for many different genetic mutations at once. So we know that most patients with MPNs will have mutations in either JAK2, CALR, or MPL but many will also have additional genetic mutations.

These additional genetic mutations may be important prognostically as we know is, we know some of these additional genetic mutations can confer either higher or lower risk of the disease progressing over time. So, I think next generation sequencing or NGS panels should be a part of the work up for most patients with MPNs at the time of initial diagnosis, and probably again, at the time that there’s any concern for disease progression in the future.

An MPN Care Partner Shares Why He’s Optimistic About the Future

An MPN Care Partner Shares Why He’s Optimistic About the Future from Patient Empowerment Network on Vimeo.

Care partner Jeff Bushnell, husband of myelofibrosis (MF) patient advocate Summer Golden, explains why he’s hopeful about their future together. Jeff shares key resources that have helped him stay educated and maintain optimism.

Summer Golden and Jeff Bushnell have been married for over 20 years. When Summer was diagnosed with myelofibrosis (MF), Jeff took on the role of care partner and advocate. Summer uses her years of theatre training and comedy to cope with her condition and help others, while maintaining positivity about the future.

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A Care Partner’s Journey: How Life Goes on After an MPN Diagnosis



It’s important to educate yourself because the more you know the less fear can overcome you. And this particular disease – the research is happening so fast, and things are changing. In my estimation, they’ll find – right now, the only cure is a stem cell transplant. It’s normally not done for older people. That in itself is innately risky. I’m convinced, probably within the next five to seven years, there will be a cure for this disease that’s not a stem cell transplant.

The research is moving that quickly on it. And if you don’t follow the disease and the people that are working on it, the specialists, you’re gonna have a much greater chance of feeling powerless and getting overwhelmed by it. As Summer believes, attitude can have a huge, huge impact on how the course of your disease runs. And a doctor would tell you the same thing.

For me, it started with Patient Power. Patientpower.info, I believe is, what it is. They have a whole section for myeloproliferative neoplasms and myelofibrosis, and they’re short videos. And you get a chance to listen to the best doctors that are the head people in this, Dr. Mesa, Dr. V [Verstovsek], and Dr. Jamieson – all the people that are really the movers and shakers. They speak. And you also get a chance to hear other patient’s stories and how they’re dealing with it. And that will give you a much better idea of what you’re facing. And you can really understand things from there. And you can get your knowledge.

Fear comes from lack of knowledge. In my job as a pilot, I flew for 50 years. I very, very rarely was afraid because my knowledge was so great and was reinforced every year by continual training that I felt prepared to handle anything that might come across to me. Knowledge is really important. It will allay your fears dramatically.

When I started online and heard about people that had been journeying with this for 10 or 15 years, initially, I had thought – well, this is a year or two, and it’ll be the end. And then I realized, plenty of people have lived with this for a long, long time. And they had a journey, and they’re doing it successfully. And that gave me confidence.

The more people you can talk to about it, the more you can put your journey in perspective. And it’s really hard to put in perspective for this particular disease because it affects everybody vastly differently. Some cancers – the progression is very, very linear. Everybody kind of goes through the same thing. This one – it depends on the mutations you have in your blood and all kinds of things like that, and some people get really bad symptoms quickly.

Others, they don’t. But the more you know about how those things affect you, the more you know and can understand about what to expect. And the more people you talk to who have it, you can find out about their journeys. It helps put yours in perspective.

I’m optimistic because I really keep up to date on what’s going on. And I see the doctors that are in the forefront of this and the research that they’re putting in and the care they have for working on this disease and the knowledge they have, and I just am quite optimistic. And as I say, I’m following the medical developments extremely closely.

I went to the ASH Conference last year. And I’ve gone to another conference that our doctor spoke at. And I’m just kinda blown away by – I’m fascinated by the science.

My advice would be find out as much as you can about it and support each other in a way that works in your own marriage.

Summer and I approach life a little bit differently. And yet, one of the reasons we do so well together is we kinda have both ends of the spectrum covered. And I sensed that when I met her 20 years ago. And we brought something to the table that each of us needed. And if you can find that in your relationship with your significant other that has the disease, what you can bring to it, what they can bring to it, you can be a tremendous support for each other.

A Care Partner’s Journey: How Life Goes on After an MPN Diagnosis

A Care Partner’s Journey: How Life Goes on After an MPN Diagnosis from Patient Empowerment Network on Vimeo.

Care partner Jeff Bushnell shares how he and his wife, patient advocate Summer Golden, have dealt with her myelofibrosis (MF) diagnosis. Jeff explains how online support and finding an MPN specialist were essential steps in helping them continue to live life to the fullest.

Summer Golden and Jeff Bushnell have been married for over 20 years. When Summer was diagnosed with myelofibrosis (MF), Jeff took on the role of care partner and advocate. Summer uses her years of theatre training and comedy to cope with her condition and help others, while maintaining positivity about the future.


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The worst part was initially. We didn’t get a myelofibrosis diagnosis.

It took about a month because in order to definitively diagnose it they have to take a bone marrow sample and send it to a pathologist and so on and so forth. So, all that time, I’m worrying about the possibilities. It could be leukemia or this, that, or the other thing. My way of handling and dealing with scariness – I’m a retired pilot – is to find out things, knowledge.

I spent a huge amount of time on the internet. The LLS Society has papers about it, and I read those.

And the more I got into it – once we found out it was myelofibrosis, I’ve read almost all of the papers that the doctors write for each other to find about this. That doesn’t interest Summer in the slightest. It interests me greatly. So, when we have an appointment with the doctor – when I’m talking to the doctor, it’s like two doctors talking to each other.

When Summer’s talking to her, they talk on a different plane. It’s much more about mental approach to things and that kind of thing.

And for me, when I think back to the beginning of when we had this and where we are now two years later, we’re living the life that we lived before she was diagnosed to be real honest with you.

We do everything that we did before she was diagnosed the same way we did it before, and it was a trip that probably everybody who gets diagnosed or deals with a person that has the disease takes. When it first happened, it hit us like bricks coming out of the sky hitting us on the face. Literally, when we first went to the hospital and she got the word that there was a problem – as I say, we lived in two separate houses – I literally was afraid to call her phone figuring she might be not there. I was that scared. And then, after we met our doctor, which was extremely fortuitous – when we went to the emergency room, the person that was there, she said these look like leukemia things.

So, she called the oncologist. The oncologist on call is our current doctor, Dr. Tiffany Tanaka, and she’s a specialist in this disease. It was like it was meant to be. And Dr. Tanaka asked the guy to do some other tests and then said, “Send her home, but tell her I need to see her this week.” So, we’re thinking all these horrible things. And its New Year’s weekend, so the clinic is closed for about five days, you know? We’re worrying and worrying and worrying.

We finally saw Dr. Tanaka, and it was like a breath of fresh air. This wonderful doctor has the ability to just communicate with the patients. I’m interested in the disease, so she communicated on my level. Summer is not interested in all the medical jargon, so she was able to explain to Summer what was going on and just very, very reassuring, very reassuring.

And then, I went and started getting information. That’s my way of coping with things. The first place I went was – I went to Patient Power and found a lot of information there.

And then I found the online myelofibrosis support group at Facebook. And that was very, very useful. When I started reading about the fact that some people had this for many, many years – then I said this is not – nothing’s gonna happen in the next year or two. We can go back to living. And once we learned more about it and spent more time with our doctor and Summer was able to live her life once she got taking the medicine – she takes Jakafi.

That controlled the basic symptoms, and we haven’t looked back. We just started living our life the way we had been living it before.

Could an MPN Clinical Trial Be Right for You?

Could an MPN Clinical Trial Be Right for You? from Patient Empowerment Network on Vimeo.

Is a clinical trial your best MPN treatment option? Dr. Ruben Mesa explains the clinical trial process and how patients may benefit from participating.

Dr. Ruben Mesa is an international expert in the research and care of patients with myeloproliferative neoplasms (MPNs). He serves as director of UT Health San Antonio MD Anderson Cancer Center in San Antonio, Texas. More about this expert here.

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Dr. Ruben Mesa:

There is much exciting research in myeloproliferative neoplasms. First, research trying to understand, why do people develop MPNs, and why do they progress. This is crucial research, and that this basic research to better understand the diseases will help us asses whether our treatments are having an impact slowing down the progression of the disease, and help us better design therapies that, hopefully, can cure these diseases.

Be reassured  that our goal as a scientific community is to cure the MPNs. Now, until we’re able to do that, we want to be able to best control them as best we can. So, the next level of research is really in new therapies; primarily drug-based therapies, but future therapies using the immune system; potentially using vaccine therapy to try to better control the disease to make the disease as neutral in your life as possible.

Our goal, short of curing the disease is to make the disease as invisible in your life as possible. Hopefully, minimal side effects, minimal symptoms, protected against risk of blood clots or bleeding, ideally, decreasing the risk of progression, and hopefully without any significant side effects from the medication your receiving.

So, that really is our goal.

 Clinical trials are a crucial way for us to improve the treatments that we have for any diseases. And in particular, in areas like myeloproliferative neoplasms where we have therapies, but we don’t have cures, clinical trials are crucial. Clinical trials are a structured way for you to be able to receive a new treatment. That treatment is closely monitored, and starts with a strong belief that that treatment is going to be beneficial for you.

Being on a clinical trial has many steps, but you are in the driver seat in each of them. So, you’re able to enroll in a study, and you’re able to decide at any point whether or not you’d like to continue on in that study. You are made clearly aware of what you’re receiving; what dose; what to expect at each and every step of that therapy.

It’s a treatment just like any other, but we use them because we are hoping that it will be better than the treatments that we have, and we do it on a clinical trial so that we can learn from that experience. If that drug is better, then we should probably expand its use and give it to other people, and have it be approved and used around the world. Or for whatever reason that therapy is not as helpful as we would like, then we learn from that, as well.

Why was it not helpful? Was it the wrong therapy? Was it targeting the wrong aspect of the disease? Were there side effects that made the therapy not beneficial? So, we learn a lot about it in either direction. Hopefully, individuals who participate in clinical trials will have a direct benefit themselves by being able to experience a new therapy that is, hopefully, better. But also, they do have the ability to help other patients now and in the future that will be facing the same disease they have.

How Does Genetic Testing Impact Your MPN Treatment Options?

How Does Genetic Testing Impact Your MPN Treatment Options? from Patient Empowerment Network on Vimeo.

How can genetic testing results impact your treatment and treatment response? Dr. Ruben Mesa provides an overview of common mutations associated with essential thrombocythemia (ET), polycythemia vera (PV) or myelofibrosis (MF) and how identification of these mutations are moving research forward.

Dr. Ruben Mesa is an international expert in the research and care of patients with myeloproliferative neoplasms (MPNs). He serves as director of UT Health San Antonio MD Anderson Cancer Center in San Antonio, Texas. More about this expert here.

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Dr. Ruben Mesa:

We are learning much more about the genetics of Myeloproliferative Neoplasm, as we truly are about the genetics of many diseases. First, when I speak of genetics, these are not the genes we think of of inherited genes that are passed from mother and father, to son or daughter. These are the genes in ourselves that potentially can change over the course of our lives, and those changes or mutations can be associated with diseases.

So, what we have learned is that the genetic changes that are associated with myeloproliferative neoplasms are important, both in terms of predicting how the diseases might behave, and also, potentially in terms of therapies. The genetic changes fall into two different groups.

There’s a first group of the most common mutations that we think are important in driving the disease. The most common is the mutation in a protein called JAK2. That’s a mutation in about half of the patients with ET, half with PV – or half with myelofibrosis, and the majority with polycythemia vera. There is mutations in calreticulin. That’s about in a third of patients with ET, and a third with MF. And then, there’s mutations in MPL, which are present in a handful of patients with ET and with MF.

But in addition to those three mutations that tend to be mutually exclusive; patients tend to only have one of those, and there’s a small group of patients that do not have any of those three. But there’s another group of mutations that we have learned about.

That we are able to obtain on panels of sometimes anywhere from 40 to 100 genes that may or may not be changed or mutated in diseases like MPNs and the implications of what those pattern of changes in those mutations have for those patients.