In the last decade, functional assays in primary CLL cells have been developed [20-29], with the aim: i) to avoid large time- and money-consuming screenings of TP53 gene mutations in non-17p deleted CLL cases; ii) to detect defects in the TP53 pathway escaping fluorescence-in situ-hybridization (FISH) for 17p deletions or mutational analysis by direct sequencing. This evidence concerns the gene TP53 and B-cell chronic lymphocytic leukemia.