NOTCH1 is aberrantly activated in chronic lymphocytic leukemia hematopoietic stem cells
To investigate chronic lymphocytic leukemia (CLL)-initiating cells, we assessed NOTCH1 mutation/expression in hematopoietic stem cells (HSCs). In NOTCH1-mutated CLL, we detected subclonal mutations in 57% CD34+/CD38-HSCs. NOTCH1 mutation was present in 66% CD34+/CD38+ progenitor cells displaying an increased mutational burden compared to HSCs. Flow cytometric analysis revealed significantly higher NOTCH1 activation in CD34+/CD38-and CD34+/CD38+ cells from CLL patients, regardless NOTCH1 mutation compared to healthy donors.