Aberrations in genes such as TP53, NOTCH1, BIRC3, EGR2 and NFKBIE were usually present and clonally dominant after the first CLL sample, whereas others were only detected at RT or during the disease course (for example CDKN2A/B, CDKN1A/B, ARID1A, CREBBP, TRAF3 and TNFAIP3) (Fig. 1c). This evidence concerns the gene CDKN1A and B-cell chronic lymphocytic leukemia.