Chronic myeloproliferative disorders
are a group of slow-growing blood cancers in which the bone marrow makes too many abnormal red blood cells, white blood cells, or platelets, which accumulate in the blood. The type of myeloproliferative disorder is based on whether too many red blood cells, white blood cells, or platelets are being made. Sometimes the body will make too many of more than one type of blood cell, but usually one type of blood cell is affected more than the others are.
There are 6 types of chronic myeloproliferative disorders: chronic myelogenous leukemia (CML), polycythemia vera, primary myelofibrosis (also called chronic idiopathic myelofibrosis), essential thrombocythemia, chronic neutrophilic leukemia, and chronic eosinophilic leukemia. Chronic myeloproliferative disorders sometimes become acute leukemia, in which too many abnormal white blood cells are made. Source: Genetic and Rare Diseases Information Center (GARD), supported by ORDR-NCATS and NHGRI.