Relapsed myelodysplastic clone differs from acute onset clone as shown by X-linked DNA polymorphism patterns in a patient with acute myeloid leukemia.

We have used a recombinant strategy based on X-chromosome-linked restriction fragment length polymorphisms to analyze clonality in a female patient with acute myeloid leukemia (AML). She presented with features compatible with a diagnosis of refractory anemia with excess of blasts in transformation, but soon progressed into overt AML. Intensive chemotherapy successfully induced a complete remission, but she later relapsed into a second myelodysplastic phase. Although analysis at presentation and relapse showed that hematopoiesis was clonal at both phases of the patient's disease, the genotype of the two clones was different. We believe the unexpected finding of a switch in clonality shows new insights into the biology and origin of AML.