miR-34a is induced in CLL after IR, and 17p deletion is associated with defective induction. (A) CLL with 17p deletion (n = 3) show impaired miR-34 up-regulation over time. In comparison, CLL with favorable genetics (13q deletion as sole abnormality; n = 3) show miR-34a up-regulation peaking around 32 hours after IR. Values are expression levels relative to the nonirradiated sample (normalized for RNA by U6 control). (B) Relative expression levels of miR-34a were low in cases with 17p deletion with and without IR. The comparison to all other cases showed significantly lower expression of miR-34a in cases with 17p deletion (n = 12) versus all other cases (n = 48; median, 2.5 vs 32.8; P < .001). Similarly, up-regulation of miR-34a was negligible compared with the majority of cases without 17p deletion (median, 5.8 [1.38-12.9] vs 121.8 [1.79-608.9]; P < .001).