ATM gene deletions have a 15-20% incidence in B-cell CLL and correlate with disease infiltrability; poor prognosis;

ATM gene deletions and P53 gene deletions are the most common deletion abnormalities in CLL and may guide the choice of treatment regimen and prognostic assessment;

Patients with CLL with del(11q) or del(17p) have a significantly worse prognosis than patients with normal chromosomes or del(13q) alone;

The 2011 edition of the NCCN specifically singles out the treatment of CLL patients with del(11q) cytogenetic abnormalities; del(11q)-CLL is more sensitive to alkylating agents, and therefore combination chemotherapy regimens containing alkylating agents are recommended in the clinic; the treatment regimen for patients with relapsed-refractory del(11q)-CL can be essentially modeled after the relapsed-refractory del(17p)- CLL;

It is one of the most common secondary chromosomal abnormalities in set cell lymphoma.