What is myelodysplastic syndrome (MDS)?
Myelodysplastic syndrome or MDS is a group of diverse bone marrow disorders in which the marrow does not produce sufficient healthy blood cells. In MDS, cells in the bone marrow are dysplastic. These defective cells die earlier than normal cells. MDS is known as bone marrow failure disorder. Though MDS can affect red blood cells, white blood cells and platelets; the most common type of MDS is shortage of red blood cells known as myelodysplastic anemia.
MDS affects the elderly as well as young people. MDS is considered a precursor to cancer as 1 in 3 patients can go on to develop acute myeloid leukemia (AML).
Most types of MDS are due to unknown causes. Others are caused by toxic exposure to radiation, chemotherapy or toxic materials like tobacco, benzene, pesticides and heavy metals like lead.
MDS is classified using the World Health Organization (WHO) classification system which was updated in 2016. It divides MDS based on cell morphology as well as other features.
- Forms of cell types (RBCs, WBCs, Platelets) which show dysplasia
- Types of low cell counts which a patient presents
- What portion of red blood cells are ring sideroblasts
- Chromosomal changes in the bone marrow cells
Based on this classification, there are six major types of MDS:
- MDS with multilineage dysplasia (MDS-MLD)
- MDS with single lineage dysplasia (MDS-SLD)
- MDS with ring sideroblasts (MDS-RS)
- MDS with excess blasts (MDS-EB)
- MDS with isolated del(5q)
- MDS, unclassifiable (MDS-U)
Signs and Symptoms
MDS rarely causes symptoms in the early stages. As the disease progresses, the patient may exhibit the following symptoms:
- Fatigue and unusual tiredness
- Shortness of breath
- Frequent infections due to low WBC count
- Easy bruising due to low platelet count
- Red spots just beneath the skin (petechiae)
Physical exams, medical history and a range of tests are usually done to confirm the diagnosis of MDS. Tests include:
- Blood tests - complete blood count
- Bone marrow biopsy - where a thin needle is used to aspirate (withdraw) a small amount of bone marrow fluid from the back or hip. The sample is tested in the lab for abnormalities
A number of different treatments are available for MDS depending on the severity and rate of progression:
- A number of medications are available to manage the condition, suppress symptoms and prevent complications. These include:
- Drugs to increase the blood cells (growth factors) like erythropoietin (to increase RBCs), filgrastim (to increase WBCs)
- Drugs to stimulate maturation of red blood cells like azacitidine and decitabine
- Drugs to suppress the immune system which can lessen the need for regular blood transfusions
- If the MDS is associated with a gene mutation called isolated del95q), a medication called lenalidomide is given
- In most cases, regular red blood cell, white blood cell or platelet transfusions may be needed on a regular basis
Bone marrow transplant (BMT) is the final cure for MDS where the abnormal bone marrow is replaced with healthy bone marrow from a donor (allogeneic transplant). However, BMT is not without side effects or risks of rejection.
Newer therapies like luspatercept are being investigated by the FDA for treating anemia in adults with low- to intermediate-risk myelodysplastic syndromes (MDS) who have ring sideroblasts and require RBC transfusions.