Clinical significance of the increased expression of the WT1 gene in peripheral blood of patients with acquired aplastic anemia.

To determine the significance of increased (WT1) gene expression in the peripheral blood of patients with acquired aplastic anemia (AA), we analyzed serial changes in mRNA copy number (WT1cn) in 63 patients with AA as well as in five patients with myelodysplastic syndromes (MDS) and seven patients with paroxysmal nocturnal hemoglobinuria (PNH). WT1cn was higher than the cut-off (≥50 copies/μg RNA) at the time of the first measurement in 41% of untreated (60-190 copies/μg RNA [median 130]) and 59% of treated (59-520 copies/μg RNA [median 150]) AA patients. Although WT1cns gradually increased in most AA patients during the 2-105 months follow-up period, they did not lead to clonal evolution except in three patients in whom the maximum change ratio of WT1cn (WT1cn-change max), defined as the ratio of WT1cn at the first examination to that of the maximum value, exceeded 20.