TP53 and B-cell chronic lymphocytic leukemia: Clonal evolution is more common after treatment than in untreated CLL (Landau et al, 2013) and small sub‐clones (e.g. TP53‐mutated sub‐clones not detected initially by conventional methods) can become predominant after relapse (Rossi et al, 2014; Sutton & Rosenquist, 2015).