Aberrantly high expression of TWIST-1 in leukemia stem/progenitor cells could be confirmed when we analyzed the expression of TWIST-1 in highly purified leukemic CD34+CD38−, CD34+CD38+ and CD34− cells isolated from patients with AML (n = 9) and CML (n = 9). This evidence concerns the gene TWIST1 and chronic myelogenous leukemia, BCR-ABL1 positive.