<b>Bone Marrow: Myelodysplasia</b> 

Myelodysplasia, also known as Myelodysplastic [pronounced MY-eh-low dis-PLAH-stic] Syndromes, are conditions that affect the bone marrow. 

The bone marrow makes blood cells. Red blood cells that carry oxygen. White blood cells that fight infection. Platelets that make clots and prevent bleeding. 

The <b>stem cells</b> in the bone marrow are the "parent cells" of the cells [red, white & platelet] which are eventually released into the blood. The myelodysplastic syndromes are caused by damage to the stem cells of the cell line[s] affected. The damage is to the DNA [genes] of the stem cells. 

<b>Patients treated for cancers with high dose radiation have a higher incidence of therapy-related myelodysplasia. Alkylating agents used in chemotherapy are known to induce myelodysplasia, as well. There are other causes, too, but these are two causes that are important to LMS patients</b>. 

If the red blood cell line is affected, the patient becomes anemic, and requires transfusions. Eventually there is an iron buildup in the body, called hemosiderosis, which can cause further problems.

If the white blood cell line is affected, the patient is more prone to get seriously ill with infections. Sometimes some of the white cell line transforms to leukemia.
 
If the platelet cell line is affected, the patient is prone to hemorrhage, and internal bleeding.
 
The progress of the condition depends upon which cell lines are affected and how badly, and whether leukemia develops. 

<b>Development of myelodysplasia puts a limit on how much radiation and chemotherapy a person can have. A patient might be cured of his or her cancer, but then succumb to myelodysplasia or leukemia as a result of the treatment for the cancer</b>. 

[Reference for this section: Harrison's Principles of Internal Medicine, 14th Edition, pp. 676-8]

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