ATM and B-cell chronic lymphocytic leukemia: In parallel, the analysis of the TP53 functional modulators, such as ATM, MDM2, NOTCH1 and NOTCH2, revealed absence of mutations in MDM2, while ATM mutations were identified in 18 (16.7%) patients and NOTCH1 and NOTCH2 mutations were documented in 10 (9.3%) and 2 (1.9%) of the B-CLL patients, respectively (Table 2).