Abnormal WT1 expression in the CD34-negative compartment in myelodysplastic bone marrow.

In normal bone marrow, WT1 expression is restricted to CD34+ cells. We assessed WT1 mRNA expression levels with quantitative, real-time reverse transcription polymerase chain reaction in normal, myelodysplastic (MDS) and secondary acute myeloid leukaemia (sAML) bone marrow subfractions, based on differentiation status. The highest WT1 expression was observed in the primitive CD34+ rhodamine-123 (rho) dull cells, both in healthy donors and MDS or sAML patients.