The most common genetic lesions in CLL are deletions of 13q14 (del 13q14), generally monoallelic in 50~60% patients (Figure 1; Table 1) [18], and involve the deletion of regions containing two long non-coding RNA genes (DLEU2 and DLEU1) which later develop clonal lymphoproliferation, recapitulating the different steps of CLL initiation and progression. The gene discussed is DLEU1; the disease is B-cell chronic lymphocytic leukemia.