To answer this question, we analyzed, among the patients with progressive disease included in both training and validation sets, how well the expression of miR-181b could identify patients with progressive/aggressive disease relative to that of other well-established prognostic markers (e.g. CLL-cell expression of unmutated IGHV genes or ZAP-70). This evidence concerns the gene ZAP70 and B-cell chronic lymphocytic leukemia.