NOTCH1 and B-cell chronic lymphocytic leukemia: In line with this hypothesis, Damm et al. demonstrated that some CLL driver mutations (e.g., SF3B1 or NOTCH1) are shared between the mature CLL clone and HSCs and hematopoietic progenitor populations, demonstrating that these mutations occur in a progenitor able to undergo lymphoid and myeloid differentiation (3, 275).