Types of Myelodysplastic Syndromes (MDS)

There are different types of myelodysplastic syndromes (MDS), and different systems can be used to classify them. Your doctor may use one or more of these systems to understand how you are affected by MDS.

How is MDS classified?

MDS is classified into types to help describe the disease, how severe it’s likely to be, and the need for treatment. Doctors use lab tests to find out the type of MDS a person has, so this might not be known until all the tests are finished.

Knowing the type of MDS a person has helps doctors recommend the best treatment options. It can also help predict a person’s prognosis (outlook).

WHO classification system for MDS

The World Health Organization (WHO) classification system for MDS includes many of the gene and chromosome changes found inside MDS cells, as well as how the cells look under a microscope. The latest version of this system, updated in 2022, divides MDS into 2 main categories.

MDS with defining genetic abnormalities

These types of MDS have specific gene or chromosome changes.

• MDS with low blasts and isolated 5q deletion (MDS-5q)
• MDS with low blasts and SF3B1 mutation (MDS-SF3B1)
• MDS with biallelic TP53 inactivation (MDS-biTP53)

Morphologically defined MDS

These types of MDS are defined mainly by how they look under a microscope (their morphology), especially the number of blasts (very immature blood cells) that are seen in the bone marrow and blood.

• MDS with low blasts (MDS-LB)
• MDS, hypoplastic (MDS-h)
• MDS with increased blasts (MDS-IB) - includes MDS-IB1, MDS-IB2, and MDS with fibrosis (MDS-f)

International Consensus Classification (ICC) system

This system was developed in collaboration with the Society for Hematopathology and the European Association for Haematopathology. The ICC system is similar to the WHO system in many ways, although it uses slightly different definitions and categories for some types of MDS.

Prognostic scores (risk groups) for MDS

Along with determining the type of MDS a person has, doctors use other factors to help predict a person’s outlook and decide how best to treat it. Some of these factors have been combined to develop scoring systems, which put people with MDS into different risk groups. To learn more about these systems, see Myelodysplastic Syndrome Prognostic Scores (Risk Groups).