"Good Morning America's" Robin Roberts announced this morning that she has myelodysplastic syndrome, or MDS. The rare syndrome is also known as preleukemia.
MDS can be broken down by its name: Myeloid refers to a type of blood cell; dysplasia means a problem with the development of those cells.
The condition occurs when "something goes wrong in your bone marrow - the spongy material inside your bones where blood cells are made," according to the Mayo Clinic.
A healthy person's bone marrow produces stem cells that mature into blood cells. But the bone marrow of a person with MDS produces abnormal stem cells that turn into defective blood cells.
Deformed cells get into the bloodstream and eventually outnumber healthy blood cells, according to the National Cancer Institute. Often the deformed blood cells don't live as long as they should, producing a shortage in the body.
There are several types of MDS, depending on the kind of myeloid cells - red blood cells, white blood cells or platelets - that are being affected. Having too few red blood cells results in anemia; having too few white blood cells can result in frequent infections.
The term "preleukemia" is a bit misleading, as most MDS cases do not become cancerous. Certain types of MDS can progress to acute myeloid leukemia, however.
MDS can be caused by exposure to chemotherapy and radiation, common cancer treatments. (Roberts is a breast cancer survivor.) Other risk factors include being over 60 years old and/or being exposed to other chemicals such as benzene, according to the Aplastic Anemia & MDS International Foundation.
Symptoms are rare during the early stage of the disease, but can include tiredness, shortness of breath and easy bruising/bleeding. Doctors generally diagnose through a blood test and a bone marrow biopsy.
Unfortunately there is no known cure for MDS. The goal for treatment is to keep healthy blood cells circulating as long as possible.
Blood transfusions can help slow the disease by replacing bad cells with good cells. Medications can also be used to increase the production of healthy cells.
Another option is a bone marrow stem cell transplant, in which doctors administer chemotherapy drugs to destroy defective blood cells, and insert healthy cells from a donor to replace them. But there are high risks involved in this procedure, according to the Mayo Clinic, even among people who are young and relatively healthy.
Roberts wrote in a statement that she will undergo chemotherapy ahead of a bone marrow transplant later this year. Her sister, who is a match, is donating the bone marrow.
Post by: Jacque Wilson -- CNN.com writer/producer