The bone marrow is the principal source of the many different types of cells that circulate in your blood stream. The term “myelodysplasia“ describes certain abnormalities in the production of these blood cells. Myelodysplastic syndromes (MDS) refer to at least five different entities, all of which interfere with the growth of blood cells in the bone marrow. The differences among them are found in the appearance of the cells under the microscope and are helpful primarily in determining prognosis.
MDS frequently progresses to a form of acute leukemia. Leukemia is a cancer of the blood cells. But in the case of leukemia, there is an overproduction of immature cells (blasts) circulating in the blood and an underproduction of healthy cells. In MDS, there is usually, but not always, only an underproduction of healthy cells. The progression to acute leukemia is so common that MDS used to be known as “preleukemia.”
The bone marrow contains stem cells, which have the capacity to become any of the cell types that circulate in the blood stream. These stem cells normally undergo a maturation process that results in mature cells with fixed functions:
- Red blood cells carry oxygen.
- Three types of granulocytes (a type of white blood cell) carry out immune functions.
- Two types of lymphocytes (a type of white blood cell) carry out immune functions.
- Macrophages and monocytes help us fight infection.
- Platelets provide a defense against bleeding and bruising.
Who Is Affected by Myelodysplastic Syndromes?
Roughly 3,000 new cases of MDS occur yearly in the United States. A similar rate of 1 to 10 per 100,000 people occurs in the rest of the developed nations. Cases without a known cause are most frequently found in older males, usually between 70 and 80 years of age; among this group, the rate rises to 25 per 100,000 people.
The incidence of MDS among younger populations is rising. This is partially due to the success of chemotherapy and radiation in treating and eradicating other forms of cancer since these therapies increase the risk of developing MDS.
Causes and Complications
The exact cause of MDS is unclear, but certain factors are believed to increase risk.
MDS may lead to a number of complications related to blood cells: