Chronic idiopathic myelofibrosis

This is a chronic disease in which bone marrow is replaced by fibrous tissue. Usually, blood is formed in bone marrow. However, in chronic idiopathic myelofibrosis, blood is formed in organs, such as liver and spleen. Other name for this condition is primary myelofibrosis. It can develop at any age, but occur more commonly in older people. Exact cause of chronic idiopathic myelofibrosis is not known, however, half of people with this condition have change, or mutations in JAK2 gene.