Wilms' tumor gene (WT1) is predominantly expressed in clonal hematopoietic cells in myelodysplastic syndromes

To determine the expression of Wilms' tumor gene (WT1) in clonal hematopoietic cells in patients with myelodysplastic syndromes (MDS), immunochemistry labelling (alkaline phosphatase anti-alkaline phosphatase) and fluorescence in situ hybridization (FISH) were coperformed on bone marrow cytospins from 18 patients whose abnormal karyotypes had been determined by G-binding analysis. Compared to 12 healthy donors, WT1 positive nucleated cells in MDS marrows were significantly higher (t = 2.30; P = 0.032). Moreover, WT1 was expressed predominantly in MDS clonal cells (with abnormal FISH signals) rather than in non-clonal cells (residual normal cells) (t = 2.19; P = 0.043).