Myelodysplastic syndromes

Definitions & Key takeaways

Myelodysplastic syndromes or just MDS, refer to a group of disorders in which the bone marrow does not produce enough healthy blood cells, usually for unknown causes. Symptoms can include fatigue, shortness of breath, and an increased risk of infection and bleeding. Treatment options for MDS include medications, transfusions, and bone marrow transplantation, depending on the severity of the condition.

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Introduction0:00–0:19

Myelodysplastic syndromes, or MDS, are a group of rare blood disorders associated with faulty development of blood cells in the bone marrow.
MDS can affect individuals of all ages, but it’s more common after the age of 60. Blood cells develop from hematopoietic stem cells, through a process called hematopoiesis.

Physiology0:19–0:48

This involves a number of divisions, and eventually, results in three types of blood cells: red blood cells, which carry oxygen around our bodies, white blood cells to help fight disease causing pathogens, and platelets that help form clots to stop bleeding.
Once these cells are fully mature, they leave the bone marrow and enter the bloodstream. In MDS, hematopoietic stem cells are damaged, so they give rise to faulty blood cells, which don’t mature, but instead persist as immature cells, called blasts.

Pathology and Symptoms0:48–2:33

These immature blood cells usually die in the bone marrow or soon after they go into the blood, so you can’t really count on them to do the job of mature blood cells.
As the condition progresses, immature blood cells gradually take over the bone marrow, which displaces and reduces the normal ones.
In most cases, the cause of MDS is not known. When this happens, it's classified as primary MDS.
In rare cases, they can be caused by chemo or radiation therapy, and this is called secondary MDS. MDS comprises a spectrum of diseases with differing potential for remaining stable or progressing to acute myeloid leukemia, or AML.
The most common feature of MDS is anemia, caused by low red blood cell levels. Symptoms of anemia include dizziness, irritability, headaches, and pale skin.
Low white blood cell levels increase the risk of bacterial and fungal infections. Finally, low levels of platelets cause excessive bruising following minimal injury and easy bleeding.
Now, MDS usually worsens with time, as normal bone marrow function diminishes. 40-50 percent of the time, MDS deteriorates into a form of cancer known as acute myeloid leukemia, or AML.
This happens when there are more than 20% blasts in the bone marrow. Diagnosis requires a variety of specialized tests including complete blood counts, a peripheral blood smear, as well as bone marrow aspiration and biopsy.

Diagnosis2:33–3:11

On a complete blood count, there may be low levels of one, two or all of the three blood cell types. On a peripheral blood smear, there may be big and oval-shaped red blood cells and abnormal white blood cells and platelets.
The bone marrow sample may show an increase in cell count with dysplastic changes in the three blood cell types. Chromosome analysis may find genetic abnormalities in affected cells.

Treatment3:11–5:03

Treatment of patients is dependent on their clinical risk status, like their risk of developing leukemia or remaining stable.
Patients’ risk status is determined by their complete blood counts, the proportion of immature cells, or blasts, in the marrow, and the type of chromosome abnormalities present in their bone marrow cells.
This information is used to generate a score known as the International Prognostic Scoring System-Revised for MDS. Other features now being evaluated are the presence of mutations in the patients’ cells, some of which are associated with a poorer prognosis.
Treatment of lower risk patients is generally aimed at improving their blood counts. Growth factors like erythropoietic growth factors can be given weekly to stimulate the production of red blood cells.
In addition patients with a chromosomal abnormality known as 5q- can be effectively treated with the drug lenalidomide. In some cases, people with MDS respond to immunosuppressive therapy with anti-thymocyte globulin.
Treatment of higher risk patients is aimed at preventing the patients’ disease from progressing to leukemia. Standard treatment includes the use of hypomethylating agents like azacitidine or decitabine.
In addition, for these patients a bone marrow stem cell transplant from a healthy donor may be an option and is the only curative treatment for MDS.
Some treatment for MDS is also supportive, and involves red blood cell transfusions to correct the anemia, platelet transfusions to treat or prevent serious bleeding, and antibiotics to treat or prevent infections.
Sometimes multiple transfusions may cause an iron buildup in the body, so an iron chelating agent, like deferasirox, may be needed to eliminate it from the body.

Review5:03–6:04

All right as a quick recap, myelodysplastic syndromes, or MDS are a group of rare blood disorders where blood cells don’t mature properly in the bone marrow.
In most cases, the cause is unknown. Complications of MDS are either chronic low blood counts or the potential to develop acute myeloblastic leukemia, when there are more than 20% blasts in the bone marrow.
MDS is associated with symptoms of anemia, easy bruising, bleeding, and increased susceptibility to infections. Diagnosis requires complete blood counts, a peripheral blood smear, bone marrow aspiration and biopsy.
Treatment depends on the patients’ risk status and in addition to specific drugs includes red blood cell transfusions to correct the anemia, platelet transfusions to treat or prevent serious bleeding, and antibiotics to treat or prevent infections.
a bone marrow transplant from a healthy donor is the only curative treatment for MDS.