What is the defining feature of myelodysplastic syndromes?

The defining feature of myelodysplastic syndromes (MDS) is ineffective hematopoiesis. In MDS, the bone marrow produces blood cells that do not mature properly, leading to a range of blood cell deficiencies, including anemia, thrombocytopenia, and neutropenia. This ineffective production occurs due to intrinsic defects in the stem cells or progenitor cells, leading to ineffective differentiation and maturation processes. As a result, even though there may be an adequate number of cells produced, they are often dysfunctional and unable to perform their normal roles in the bloodstream.

In contrast to other hematological disorders, in which there might be increased populations of certain cell types or markers of malignancy, MDS is characterized primarily by this failure of normal blood cell production, which often progresses towards acute myeloid leukemia in some cases. The term 'ineffective hematopoiesis' captures the essence of the disease, highlighting both the presence of inadequate blood cell counts and the quality of those produced.