Myeloproliferative disorders

Myeloproliferative disorders – sometimes called myeloproliferative neoplasms – are cancer-like diseases in which too many blood cells are produced in the bone marrow. This hinders the normal production of blood cells. The excess blood cells can also disrupt the function of the blood.

There are many types of myeloproliferative disorder, involving different cell types. Common types are:

Myeloproliferative disorders differ from leukaemia in the major type of cell being produced. In myeloproliferative disorders, the bone marrow produces excessive numbers of mature blood cells that function normally, but are present in greater-than-normal numbers. In leukaemia, the cells tend to be immature. Sometimes myeloproliferative disorders can progress to acute leukaemia.

Specific genetic changes in blood cells have been pinpointed as the cause of many myeloproliferative disorders. These genetic changes cause over-active signalling in bone marrow cells, resulting in uncontrolled production of blood cells.

A common genetic defect frequently associated with myeloproliferative disorders is:

• JAK2V617F, an altered version of the gene for the JAK2 signalling protein. This is often found in essential thrombocythaemia, polycythemia vera and primary myelofibrosis.

Myeloproliferative disorders are severe and potentially fatal. These diseases can progress slowly for many years. However, some can progress to acute leukaemia, a more aggressive disease.

Most myeloproliferative disorders cannot be cured. Treatments can relieve the symptoms and slow the disease’s progress.

Targeted therapies are showing promise for treating myeloproliferative disorders. Specific inhibitors of JAK2 are effective in treating some people with myeloproliferative disorders.

The Leukaemia Foundation provides advice and support for people with myeloproliferative disorders.

WEHI researchers are not able to provide specific medical advice specific to individuals. If you have cancer and wish to find out more information about clinical trials, please visit the Australian Cancer Trials or the Australian New Zealand Clinical Trials Registry, or consult your medical specialist.