Targeted amplicon deep sequencing (TS) across a panel of the seven most frequently mutated genes in CLL (SF3B1, NOTCH1, ATM, TP53, MYD88, KRAS and BIRC3) was performed on DNA collected pretreatment from (i) the peripheral blood (PB) mononuclear layer (MNL) containing the leukaemic cells, (ii) plasma and (iii) matched normal DNA. This evidence concerns the gene ATM and B-cell chronic lymphocytic leukemia.