Analysis of mutational signatures within the putatively hypermutated regions that we identified did not identify any specific mutation process that could explain the pattern of base substitutions in these regions (Fig. 2), although it is possible that this mutational pattern is partially due to a process identified in CLL and lymphoma that is implicated with AID induced somatic hypermutation [27]. Here, AICDA is linked to B-cell chronic lymphocytic leukemia.