Mapping of deletions involving chromosome bands 11q14 to 11q24 in 37 MCL by FISH. Chromosome 11 ideogram, band designation, CEPH YAC address, DNA locus, and genes contained in the probe set are given. YACs 950c12 through 785e12 form a contig and therefore allowed a precise deletion mapping. del, deletion (1 FISH signal); di, disomy (2 FISH signals); 3, partial trisomy in MCL no. 1 (3 FISH signals). The extent of the deletion in each case is indicated by shading. The half shading of YAC 801e11 in MCL no. 33 indicates partial deletion of this probe. Three MCL (nos. 1, 3, 4) were included in a previous study.14 The minimal deletion region lost in all MCL analyzed is the centromeric part of YAC 801e11 to which the ATMgene maps. The centromeric border of the minimal deletion is defined by MCL nos. 8 and 21. The telomeric border is defined by MCL no. 33 exhibiting loss of PAC ATM-1 and -2 and retention of 2 signals for YAC 801e11.