TP53 gene defects have been observed as primarily subclonal events in CLL patients, often emerging at later disease stages.9 The frequency of TP53 defects at diagnosis or before first therapy is only between 5 and 15%,2, 3, 10, 11 but the proportion of affected patients is significantly higher after treatment and has been reported to be as high as 44% in a fludarabine-refractory cohort.12 Clonal evolution of genetic abnormalities including TP53 defects is well evidenced in CLL. Here, TP53 is linked to B-cell chronic lymphocytic leukemia.