Interestingly, activating mutations affecting NOTCH1 are also present in 4–13% of B-cell chronic lymphocytic leukemia (B-CLL) cases (11, 12), and very recently frequent non-mutational NOTCH1 activation in B-CLL has also been reported, irrespective of NOTCH1 mutational status (13). This evidence concerns the gene NOTCH1 and B-cell chronic lymphocytic leukemia.