Interestingly, however, when larger cohorts were analyzed, the incidence of NOTCH1 and SF3B1 mutations was not significantly different between HC-MBL and Rai 0-CLL (NOTCH1: 8.2% vs. 13.1%; SF3B1: 4.7% vs. 3.8%) (Figure 2) (21). Here, SF3B1 is linked to B-cell chronic lymphocytic leukemia.