MDS Subtypes

There are several kinds (subtypes) of MDS. The subtype is determined from the results of the blood and bone marrow tests.

WHO Classification

The current WHO classification guidelines identify six subtypes.The current WHO classification guidelines, which were updated in 2022, groups MDS based on genetic abnormalities and morphologically defined features (the appearance and number of the cells under a microscope).

The subtypes are determined by the following:

  • Low blood cell counts (red blood cells, white blood cells and/or platelets)
  • Dysplasia (cells that have an abnormal shape or size)
  • The number of blast cells (immature blood cells) in the blood and bone marrow
  • Changes to the chromosomes and genes in bone marrow cells that are associated with MDS

MDS with Defining Genetic Abnormalities

  • 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

  • MDS with low blasts (MDS-LB)
  • MDS with low blasts and ring sideroblasts (MDS-LB-RS)
  • MDS, hypoplastic (MDS-h)
  • MDS with increased blasts

For a detailed list of the WHO classification system of MDS subtypes see the free LLS booklet Myelodysplastic Syndromes.

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