Myelodysplasia
Myelodysplasia (myelodysplastic syndrome, usually shortened to MDS) is a rare blood disorder, and can be deadly. It is associated with dysfunctional bone marrow, resulting in a failure of production of red blood cells, white blood cells and platelets. Chemotherapy and bone marrow transplant are typically used to treat it.
History
Since the early 20th century it began to be recognized that some people with acute myelogenous leukemia had a preceding period of anemia and abnormal blood cell production. The early identification, characterization and classification of this disorder were problematical. This condition was first discussed using the term "preleukemia" and was only recognized in patients retrospectively. The designation "myelodysplastic syndrome" (MDS) was made official in 1976 by an international study group.
The cause of MDS
MDS is due to a genetic defect in a particular type of cell, the multi-potent blood stem cell. The normal functioning of the MDS patient's bone marrow is disrupted by the presence of the abnormal blood stem cells. When normal stem cells diivide, they display a careful balance between production of more stem cells that stay in the bone marrow and production of differentiated blood cells that are released from the marrow to function in the blood stream. In MDS there are too many stem cells being produced and not enough differentiated and functioning blood cells. Death from bleeding (due to lack of platelets) or infection (due to lack of lymphocytes) is the outcome for about 60% of MDS patients. In about 40% of patients there is a further genetic mutation in one of the abnormal blood stem cells resulting in acute leukemia. The progression of MDS to leukemia is a good example of the multi-step theory of carcinogenesis in which a series of mutations occur in an initially normal cell and transform it into a cancer cell.
Incidence of MDS
The exact number of people with MDS is not known because it can go undiagnosed and there is no mandated tracking of the syndrome. Some estimates are on the order of 10-20,000 new cases each year in the U.S.A.. The incidence is probably increasing as the age of the population increases.Treatment
Treatment is complicated by the fact that different MDS patients have different severities and variations of symptoms. Therapy is typically supportive care. Transfusions of platelets can help control bleeding. Antibiotics can limit infections. Large medical centers can provide specialized therapies. Anti-cell-proliferation chemotherapy is often used. To be effective, chemotherapy must be aggressive and about 30% of the patients are killed by the highly toxic chemotherapy drugs. A bone marrow transplant is typically required following the most aggressive chemotherapy because all of the patient's blood stem cells are destroyed by the treatment. There is continuing research and clinical trials aimed at finding better treatments.External links