Molecular cytogenetic delineation of the critical region of 11q deletions in B-CLL (see ref 11). In a previous study, we identified a 2- to 3-Mb sized commonly deleted region in B-CLL tumors that was defined by YAC clones 801e11, 975h6, and 755b11. Clone 755b11 that we used for deletion screening in the present study also contained the breakpoints of two balanced translocations.