ATM gene mutations can be nonsense or missense substitutions, in-frame or frameshift insertions or deletions, and are present in 25% of patients with CLL at diagnosis and are commonly associated with unmutated IGHV, ZAP-70 expression, and presence of del(11q) (30%-40%) by FISH (65). This evidence concerns the gene ATM and B-cell chronic lymphocytic leukemia.