There are many subtypes of MDS. The subtype is determined using the results of blood and bone marrow tests. (Learn about these tests and how MDS is diagnosed.)
MDS subtype is determined using either the World Health Organization (WHO) classification system or the French-American-British (FAB) classification system, but the WHO classification is more commonly used today. Both systems take into account a number of features of the abnormal cells. These include the number and type of cytopenias (shortages of specific types of blood cells) and the number of blasts in the bone marrow and circulating blood.
Once our doctors know the MDS subtype, we can select the most-effective treatment, decide when to start therapy, and predict the course of the disease.
WHO Classification System for MDS Subtypes
The WHO classification system was updated in 2016. The WHO subtypes depend on the percentage of myeloblasts in the bone marrow, the presence of abnormal red blood cell precursors (called ringed sideroblasts) in the bone marrow, the number of abnormal cell types known as dysplastic lineages in the bone marrow, and the genetic profile of the bone marrow cells.
The characteristics of the most common subtypes of MDS are:
MDS with single-lineage dysplasia (MDS-SLD)
- one or two cytopenias in the blood
- one dysplastic lineage in the bone marrow
- less than 5 percent blasts in the bone marrow
MDS with multilineage dysplasia (MDS-MLD)
- one to three cytopenias in the blood
- two or three dysplastic lineages in the bone marrow
- less than 5 percent blasts in the bone marrow
MDS with ring sideroblasts (MDS-RS)
MDS-RS with single-lineage dysplasia (MDS-RS-SLD)
- one or two cytopenias in the blood
- one dysplastic lineage in the bone marrow
- less than 5 percent blasts in the bone marrow
- 15 percent or more ringed sideroblasts or 5 percent or more ringed sideroblasts in the presence of an SF3B1 mutation
MDS-RS with multilineage dysplasia (MDS-RS-MLD)
- one to three cytopenias in the blood
- two or three dysplastic lineages in the bone marrow
- less than 5 percent blasts in the bone marrow
- 15 percent or more ringed sideroblasts or 5 or more ringed sideroblasts in the presence of an SF3B1 mutation
MDS with isolated del(5q)
- one or two cytopenias in the blood
- one to three dysplastic lineages in the bone marrow
- less than 5 percent blasts in the bone marrow
- cytogenetics showing del(5q) alone or with one additional abnormality except monosomy 7 or del(7q)
MDS with excess blasts (MDS-EB)
MDS-EB-1
- one to three cytopenias in the blood
- up to three dysplastic lineages in the bone marrow
- 5 to 9 percent blasts in the bone marrow or 2 to 4 percent blasts in the blood
MDS-EB-2
- one to three cytopenias in the blood
- up to three dysplastic lineages in the bone marrow
- 10 to 19 percent blasts in the bone marrow or 5 to 19 blasts in the blood
How Can I Learn More about My Prognosis?
In addition to the classification systems mentioned above, your doctor can also get a sense of your prognosis by using the Revised International Prognostic Scoring System (IPSS-R). This system is based on three factors:
- the percentage of immature blood cells in the bone marrow
- complete blood count results
- the pattern of cytogenetic (chromosomal) abnormalities
Your doctor will use this scoring system to help determine the extent of the disease, your best treatment options and when to start treatment, and your prognosis and risk of later developing acute leukemia.
After seeing your blood test and bone marrow test results, your hematologist can confirm your IPSS-R score and discuss with you how it affects your treatment plan.
Request an Appointment
Available Monday through Friday, to (Eastern time)