Myeloproliferative disorders are a group of conditions that cause red and white blood cells and platelets to grow abnormally in bone marrow, and while the associated conditions are serious, people can live for many years, depending on the specific disorder they have, notes University of Maryland Medical Center. Polycythemia vera, essential thrombocytosis, primary or idiopathic myelofibrosis, and chronic myelogenous leukemia are myeloproliferative disorders.
Polycythemia vera is a myeloproliferative disorder in which the bone marrow produces too many blood cells, primarily red blood cells, according to University of Maryland Medical Center. Essential thrombocytosis happens when the body produces too many platelets, which can lead to clots that block blood vessels. Primary or idiopathic myelofibrosis, also called myelosclerosis, is a condition in which the body produces too much collagen or fibrous tissue in the bone marrow, reducing the marrow's ability to produce blood cells. Chronic myelogenous leukemia is a cancer in which the body produces abnormal white blood cells in the bone marrow.
The symptoms of myeloproliferative disorders vary based on the specific diagnosis, though each disorder other than essential thrombocytosis leads to an enlarged spleen, reports University of Maryland Medical Center. Doctors do not know what causes the overproduction of cells that leads to myeloproliferative disorders, as of 2015, but theories include genetics and overexposure to radiation, electrical wiring or chemicals.