Whereas up to two-thirds of del17p13 CLL also harbor TP53 mutations, a fraction of CLL carries TP53 mutations without del17p13 [2,25,41], and TP53 mutations have been shown to have a negative prognostic relevance also in the absence of TP53 deletion [42]. The gene discussed is TP53; the disease is B-cell chronic lymphocytic leukemia.