Our results also revealed seven patients with BCP-ALL bearing large interstitial deletions that all started within intronic regions of the COBL, which is localized ~611 Kb downstream of IKZF1. The frequency of COBL rearrangements varied for complete (16.7%) and intragenic (0%) deletions of IKZF1 at diagnosis, and were found in 4.2% of cases at relapse. The gene discussed is IKZF1; the disease is acute lymphoblastic leukemia.