According to the above mentioned results, we propose a diagnostic flowchart based on the investigation for 17p deletion by FISH and the evaluation of TP53 pathway functionality by the assay combining western blotting for TP53 and qRT-PCR for CDKN1A upon a 24-hour in-vitro incubation of CLL cells with the non-genotoxic TP53 activator Nutlin-3. This evidence concerns the gene CDKN1A and B-cell chronic lymphocytic leukemia.