Myelodysplastic syndromes (MDS) are disorders that affect the bone marrow. Bone marrow (specifically, red bone marrow) is the soft spongy tissue found at the center of many bones where most of the body’s supply of blood cells are produced.
When a person has MDS, the bone marrow produces blood cells that do not mature or function normally. This can affect red blood cells, white blood cells, and platelets. Low levels of blood cells can lead to anemia, lowered immunity, and bleeding problems.
MDS is most common in adults over the age of 65, though it can occur at younger ages.
MDS is a type of cancer
Previously, MDS has been known as “pre-leukemia” or “smoldering leukemia.” MDS is now recognized as a type of cancer instead of a condition that leads to cancer.
Like other forms of cancer, MDS are caused by genetic mutations, changes in the DNA of cells that cause the creation of abnormal cells. In some instances, these are genetic mutations that are inherited from a person’s parents. But it’s more common for mutations that cause MDS to occur later in a person’s life.
Diagnosis should include tests to look for different types of mutations that have occurred in MDS cells. For example, pieces of DNA that may have been damaged, lost, or rendered inactive.
Understanding an MDS diagnosis
MDS can be categorized into different types based on prognosis, genetic variations, and what the abnormal cells look like when examined with a microscope.
These factors are important when making treatment decisions, but understanding the language around these terms can also feel a bit overwhelming. Your healthcare team will be your best source of information about a diagnosis and the meaning of different terms related to a diagnosis.
Here are a few terms that may help you understand a diagnosis and talk to your healthcare team:
- Blasts. A blast refers to an immature blood cell. The percentage of blood cells that are blasts are an important piece of information when diagnosing MDS.
- Anemia. This is a condition where a person has a lower-than-normal amount of healthy red blood cells. This is the most common manifestation of MDS.
- Cytopenia. This refers to having a lower-than-normal amount of healthy blood cells. Anemia is a type of cytopenia. Cytopenia can also refer to having low numbers of platelets (thrombocytopenia), white blood cells (leukopenia), and mature white blood cells called neutrophils (neutropenia).
- Refractory. This is a term for when a condition does not respond to treatment. For example, refractory anemia will not respond to standard anemia therapies.
- Ringed sideroblasts. These are immature red blood cells that contain ring-shaped deposits of iron. These can be found in lab tests that examine blood and bone marrow samples.
- Dysplasia. “Dysplasia” means abnormality. With MDS, this refers to abnormalities in different blood cells.
- Single and multilineage. Single lineage MDS features abnormalities in one type of blood cell (for example, red blood cells). Multilineage MDS features abnormalities in multiple types of blood cells (for example, abnormalities in both red and white blood cells).
- Inactivation. This refers to a loss-of-function mutation, a mutation that causes a gene (a segment of DNA) to become inactive (or much less active).
- Deletion. This is a type of mutation where a piece of DNA is removed or lost as a cell replicates.
- Hypoplastic. Hypoplastic refers to a type of MDS where there are low numbers of blood-forming cells in the bone marrow.
- Fibrosis. This refers to bone marrow fibrosis, the formation and buildup of scar tissue in the bone marrow.
Lower-risk and higher-risk MDS
MDS is typically categorized as lower-risk or higher-risk based on the number of blasts, the number of healthy blood cells in the blood, and genetic mutations. Lower-risk typically requires less aggressive treatment, while higher-risk typically requires more aggressive treatment.
Again, if you have questions about a diagnosis, words or terms related to diagnosis, and what this means for treatment and prognosis, ask your healthcare team for an explanation. Your healthcare team can also explain what these terms mean for a prognosis and treatment.
Sources: Jennifer L. Dotson and Yehuda Lebowicz. ... + 24
- Jennifer L. Dotson and Yehuda Lebowicz. Myelodysplastic Syndrome. StatPearls. July 18, 2022.
- MD Anderson Cancer Center. Myelodysplastic Syndrome.
- NCI Dictionary of Cancer Terms. Bone marrow.
- American Cancer Society. What Are Myelodysplastic Syndromes (MDS)?
- American Cancer Society. Key Statistics for Myelodysplastic Syndromes (MDS).
- American Cancer Society. What Causes Myelodysplastic Syndromes (MDS)?
- American Cancer Society. Types of Myelodysplastic Syndromes (MDS).
- Aplastic Anemia and MDS International Foundation. MDS Types.
- NCI Dictionary of Cancer Terms. Blast.
- Cleveland Clinic. Cytopenia.
- Aplastic Anemia and MDS International Foundation. Glossary of Terms.
- NCI Dictionary of Cancer Terms. Refractory.
- Cleveland Clinic. Sideroblastic Anemia.
- Damilola Ashorobi, Anahat Kaur, and Anil Chhabra. Sideroblastic Anemia. StatPearls. December 11, 2024.
- Arshi Syal. Sideroblastic Anemias. Medscape. August 27, 2024.
- NCI Dictionary of Cancer Terms. Dysplasia.
- Siteman Cancer Center. What are Myelodysplastic Syndromes?
- National Organization for Rare Disorders. Myelodysplastic syndrome with single lineage dysplasia.
- National Organization for Rare Disorders. Myelodysplastic syndrome with multilineage dysplasia.
- ScienceDirect. Loss of Function Mutation.
- MedlinePlus. What is a gene?
- National Human Genome Research Institute. Deletion.
- Theodoros Karantanos and Amy E. DeZern. Biology and clinical management of hypoplastic MDS: MDS as a bone marrow failure syndrome. Best Practice & Research Clinical Haematology. Vol. 34, No. 2.
- Akriti G. Jain, Ling Zhang, John M. Bennett, and Rami Komrokji. Myelodysplastic Syndromes with Bone Marrow Fibrosis: An Update. Annals of Laboratory Medicine, 2022. Vol. 42, No. 3.
- American Cancer Society. Myelodysplastic Syndrome (MDS) Prognostic Scores (Risk Groups).
