The exact cause remains unknown but MPNs are monoclonal blood cell disorders. This means that MPNs result from a change in the DNA of a single blood stem cell, which leads to too many abnormal cells developing. This problem becomes more widespread when the original affected stem cell divides and produces clones which all have the same defect.

Doctors don’t know exactly why some people get them but there are a few factors that may raise your risk:

• Exposure to certain chemicals and to radiation might increase your chances but it’s unusual to be around levels that are high enough to cause illness.
• One study found a history of any autoimmune disease – illnesses where your body’s immune system becomes overactive and attacks your body’s own tissues, such as Crohn’s disease or hypothyroidism – could raise your risk.
• Family history might play a part. MPNs aren’t hereditary, and the gene mutations are acquired during someone’s life, rather than being passed on from a parent. But first-degree relatives often have the same genetic tendency that predisposes people to develop MPNs.
• Age is key – the majority of people with MPNs are over 60.
• Gender is a risk factor for PV as it affects slightly more men, and in ET which affects more women than men. MF affects men and women in roughly equal numbers.
• Your race might play a role – research has shown that MF is more common in white people and Ashkenazi Jews.

MPNs are considered rare diseases, which is why you may never have heard of them until you were diagnosed. In the US, a study in 2010 showed MF affected just 3.6 to 5.7 people for every 100,000 population while there were 45-57 cases of PV per 100,000 and 39-57 cases of ET per 100,000.The accepted Canadian definition of a rare disease is one that affects fewer than 50 people out of 100,000, so it’s not surprising most people haven’t heard of MPNs.

Cancer occurs when normal cells grow in an uncontrolled way, and there has been some debate in medical circles about whether or not MPNs are types of cancer.The Canadian Cancer Society refers to them as “disorders” among the different types of blood cancers (leukemia)while the Leukemia and Lymphoma Society of Canada calls them “blood cancers.”

MPNs can’t be cured, with the potential exception of MF in a small minority of people who have a bone marrow or stem cell transplant. Patients are individually assessed as transplants are not commonly recommended. This is due to a high risk of life-threatening side effects, as well as a risk that the new stem cells will react against your body’s healthy tissues. Transplants are often only considered an option for fit patients with advanced disease. The first step involves very high levels of chemotherapy or radiation therapy.

For information about managing MPNs, click here

MPNs largely affect men and women over 60,or whom pregnancy isn’t on the agenda, but they can sometimes develop in people of childbearing age, too. As MPNs are rare, very little research has been done in this area so there are no specific guidelines for doctors. While pregnancy isn’t thought to affect MPNs, how your symptoms are managed may have an effect. Plus, there are extra considerations for pregnant women with MPNs, as pregnancy may further increase the risk of having a blood clot.If you’re thinking about trying to conceive, always speak to your doctor about whether now is the best time. And if you do become pregnant, be aware that you’ll need specialist care.