blood disorders
Polycythemia Vera
Causes of Polycythemia Vera
More than 95% of people with polycythemia vera have a mutation in theJAK2gene. This mutation causes excess blood cell production. In addition, mutations in the calreticulin gene (CALR) and other genes have been found in some people with polycythemia vera. These mutations lead to sustained activation of JAK2 kinase, the enzyme that causes excess red blood cell production. Blood cells are normally produced in the bone marrow. Sometimes the spleen and liver also start producing blood cells. Eventually, in a small percentage of people, the bone marrow develops Myelofibrosis with scarring and is less able to produce blood cells. 