Increased WT1 mRNA and protein expression in trisomy 8 MDS. (A) Quantitative RT-PCR for WT1 mRNA expression was performed on BMMNCs from patients with trisomy 8 (n = 12), MDS patients with other cytogenetic abnormalities (n = 12), and healthy donors (n = 22) as described in “Measurement of WT1 mRNA by real-time quantitative RT-PCR.” Patients with trisomy 8 had significantly increased WT1 mRNA expression levels compared with non–trisomy 8 MDS patients (P = .04) and healthy donors (P < .001). (B) The extent of WT1 overexpression was proportional to the percentage of trisomy 8 cells in the BMMNC sample (P = .0004; R² = 0.7705). (C) Immunoblots were performed on total protein extracted from the CD34⁺ of 7 patients responsive to IST (4 of whom had trisomy 8), 3 patients not responsive to IST, and 4 healthy controls; representative examples are shown with densitometry readings expressed as the ratio of WT1 protein/actin protein. Patients who later responded to IST had increased protein ratios of WT1/actin.