Myelofibrosis occurs when blood stem cells develop a genetic mutation. Blood stem cells have the ability to replicate and divide into the multiple specialized cells that make up your blood — red blood cells, white blood cells and platelets.

It's not clear what causes the genetic mutation in blood stem cells.

As the mutated blood stem cells replicate and divide, they pass along the mutation to the new cells. As more and more of these mutated cells are created, they begin to have serious effects on blood production.

The end result is usually a lack of red blood cells — which causes the anemia characteristic of myelofibrosis — and an overabundance of white blood cells with varying levels of platelets. In people with myelofibrosis, the normally spongy bone marrow becomes scarred.

The gene mutation that occurs in most people affected by myelofibrosis is sometimes referred to as JAK2. Other gene mutations also may be associated with myelofibrosis.

Aug. 01, 2014

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