Moreover, since BIRC3 disruption in CLL patients has been associated with fludarabine refractoriness even in TP53 wild-type CLLs [10], we tested HG3-del(11q) clones (with or without BIRC3 disruption) for evidence of resistance to fludarabine treatment. This evidence concerns the gene BIRC3 and B-cell chronic lymphocytic leukemia.