In contrast, Jonckheere-Terpstra testing showed no significant correlation trend between BCL-xL expression and increasing Rai stage, ZAP70-positive/negative, CD38-positive/negative, p53 deletion (17p)/normal status (Additional file 4: Figure S4), or commonly detected chromosomal abnormalities (Table 2), thus indicating that BCL-xL expression is independent of known CLL prognostic markers. This evidence concerns the gene ZAP70 and B-cell chronic lymphocytic leukemia.