BCR and B-cell chronic lymphocytic leukemia: NOTCH1 is preferentially targeted in specific clinical and biological groups of CLL (Sportoletti et al., 2010), including cases that have developed into Richter syndrome (Rossi et al., 2012; Villamor et al., 2013), cases harboring unmutated‐IGHV genes, cases harboring a subset eight BCR configuration, and cases harboring trisomy of chromosome 12 (Del Giudice et al., 2012; Fabbri et al., 2011; Rossi et al., 2012, 2013; Sportoletti et al., 2010).