ABSTRACT
The myelodysplastic syndrome(MDS) comprise a heterogeneous group of clonal disorders.A unique aspect of MDS is the notion that both bone marrow failure and the propensity toward development of acute leukemia coexist. Origin of abnormal clone with MDS occurs at the level of multipotent progenitors or above it. Recently some kinds of MDS were observed the abnormal clone has been potentially originated from normal CD+34 CD-38 Thy-1 + hematopoietic stem cells. The abnormal clones with different chromosomal abnormality have different distribution. With the propotion of abnormal clonality increasing MDS has aggravated. Coherent result will provide new insight into the clinical diagnosis, treatment and prognosis of MDS by strengthening the research of MDS clonality.