... 2Laboratory of Experimental Oncology and Lymphoma Unit, Oncology Institute of Southern Switzerland, Bellinzona, Switzerland, 3Division of Hematology and Transplant, Department of Clinical Medicine and ... deletion The most common lesion in CLL is chromosome 13q14.3deletion, occurring in half of the cases [4]. The deletion isoften interstitial and can be homozygous in up to 15% of the cases [4]. ... involved in the DNA repair and its inactivation impairs the response of CLL cells to chemotherapy [26,28]. It has been suggestedthat, for the complete lack of ATM function, the otherATM allele...