XPO1 and B-cell chronic lymphocytic leukemia: Specifically, the dominant clone in the two cases with a double mutation in NOTCH1 and XPO1 (ID-34 and ID-49) was always NOTCH1 rather than XPO1. Therefore, since XPO1 is still present in a small part of the CD34+CD19− cell population and greatly enriched on the total CD34+ fraction, we may consider that cells carrying XPO1 mutations are expanded in an intermediate event of B-CLL differentiation, given the previous possible events such as 13q- and 11q- abnormalities or MYD88 and NOTCH1 mutations.