Myeloproliferative neoplasms, or MPNs, are a group of chronic blood cancers in which the bone marrow makes too many red blood cells, white blood cells, or platelets
In healthy patients, the bone marrow makes blood stem cells that become mature blood cells over time. A blood stem cell can become a lymphoid stem cell or a myeloid stem cell. However, in MPNs, too many myeloid stem cells become one or more types of blood cells (red blood cells, white blood cells [granulocytes] or platelets). These neoplasms can slowly get worse as the number of extra blood cells increases, and eventually these abnormal clones take over the marrow.
Studies have shown that there is an appearance of the abnormal stem cells in MPNs that is due to a mutation in a gene that is not present at birth. In Philadelphia-chromosome-negative MPNs, the most common mutation is on the Janus kinase 2, or JAK2, gene.
MPNs may not have symptoms, especially if the disease is in early stage; however, some signs can include headache, fatigue, shortness of breath, easy bruising or bleeding, tiny red spots under the skin, unexplained weight loss, night sweats, fever or itching.