Myelodysplastic Syndrome

The hallmark of neoplastic disease, including myelodysplastic syndrome (MDS), is clonal proliferation of cells. Clonal proliferation is the consequence of acquired somatic mutation that confers a proliferative advantage to cells. For the myelodysplastic syndrome, the ability to identify clonally derived cells has provided valuable information about the molecular pathogenesis of the disease, the processes that govern the transition of MDS to acute myelogenous leukemia (AML), and diagnostic and prognostic information that is useful in the clinical approach to MDS. In this section, we will review the various methods that are available for determination of clonal derivation of cells in MDS, and briefly review the contributions that these analyses have provided to our understanding of the molecular pathogenesis of MDS. The theory behind each of the approaches will be described, as well as the advantages and potential pitfalls of each of the methods. It will be shown that no one method is adequate for evaluation of clonality, and that results of clonality assays must be interpreted with caution, especially in the context of clinical decision making.