Myelodysplastic syndromes (MDS) are a rare group of blood disorders that occur as a result of improper development of blood cells within the bone marrow.
About 10,000 to 15,000 people are diagnosed with myelodysplastic syndromes in the United States each year. Although MDS can affect people of any age, more than 80% of cases are in people over age 60. MDS is more common in men than in women.
General symptoms associated with MDS include fatigue, dizziness, weakness, bruising, bleeding, frequent infections, and headaches. In some cases, MDS may progress to life-threatening failure of the bone marrow or develop into acute leukemia. The exact cause of MDS is unknown. There are no certain environmental risk factors.
Causes of MDS
In MDS, the bone marrow does not make enough normal blood cells for the body. One, two or all three types of blood cells — red blood cells, white blood cells and platelets — may be affected. The marrow may also make immature cells called blasts. Blasts normally develop into red blood cells, white blood cells or platelets. In MDS, the blasts are abnormal and do not develop or function normally.
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Most often the cause of the changes to the bone marrow is unknown. This is called de novo MDS. In a small number of people, MDS might be linked to heavy exposure to some chemicals, such as certain solvents, or to radiation. MDS can also be caused by treatment with chemotherapy or radiation therapy for other diseases. This is called treatment-related MDS or secondary MDS. Treatment-related MDS is often more severe and difficult to treat than de novo MDS.
MDS Symptoms
The symptoms of MDS depend on how severe the disease is. Many people with MDS have no symptoms when they are diagnosed. Their disease is found through a routine blood test. If a person does have symptoms, they are caused by low numbers of blood cells:
- Red blood cells carry oxygen throughout the body. Low numbers can lead to anemia — feeling tired or weak, being short of breath and looking pale. Anemia is the most common symptom of MDS.
- White blood cells fight infection. Low numbers can lead to fever and frequent infections.
- Platelets control bleeding. Low numbers can lead to easy bleeding or bruising.
In severe MDS, infection or uncontrolled bleeding can be life-threatening.
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Diagnosis
MDS is one of several diseases with these symptoms. Doctors look at samples of blood and bone marrow to diagnose MDS. They also look for changes in the chromosomes of bone marrow cells (cytogenetics).
MDS can be hard to diagnose. Careful study of blood and marrow samples is needed to tell MDS apart from other diseases with similar signs and symptoms, such as aplastic anemia. Blood and marrow samples are often tested several times over two or more months to find out whether the disease is stable or getting worse.
MDS is a group of diseases that have many differences. It is important to diagnose the type of MDS to make the best treatment choices. With some types of MDS, a person may live with few symptoms for years, while other types can be life-threatening within months. In addition, some types of MDS are more likely than others to develop into acute myelogenous leukemia (AML). AML that develops from MDS can be hard to treat.
