Chromosomal aberrations and telomere dysfunction in CLL cells according to their in vitro sensitivity to apoptosis. (Ai-iii) Representative examples of CLL cells in metaphase from CLL-R (Ai), CLL-S (Aii), and healthy B cells from healthy donors (Aiii). Telomeres are labeled with a telomere-specific (C₃TA₂)₃–Cy3-labeled peptide nucleic acid probe (PNA; red fluorescence). Chromosomes are counterstained with DAPI (blue). Arrows indicate the sites of genomic aberrations resulting from telomere dysfunction. (Aiv-vi) De novo labeling of the metaphase cells shown in panels Ai-iii with CLL multicolor probes to detect chromosomes 11, 12, 13, and 17 and specific chromosomal aberrations therein. Chromosome 11 is labeled green on region 11q22–23. Chromosome 12 is labeled green on centromeric sequences. Chromosome 13 is labeled aqua on region 13q34 and red on region 13q14. Chromosome 17 is labeled red on region 17p13. der indicates abnormal chromosome (derivated). In these cases, this mark shows events of deletions. (B) Representative examples of chromosomal aberrations at the telomeres in CLL cells. Comparison of the average number of telomeric aberrations between CLL-R, CLL-S, and B cell samples from healthy donor controls. Bars represent the mean ± SD. (C) Comparison of the average number of telomeric aberrations and other defined chromosomal aberrations in CLL cell samples. Ctrl indicates control (healthy donors); del 11q22, 11q22 deletion; del 13q14+, 13q14 deletion associated with del 11q22 or del 17p13 detected by FISH; and complex karyotype, karyotype with more than or equal to 3 chromosomal aberrations. Bars represent the mean ± SD. (D) Comparison of average number of telomeric aberrations between 2 CLL cell subclones from the same patient (CLL-12). One subclone has a 13q14 deletion alone, whereas the second has both a 13q14 and 11q22 deletion. ctrl indicates cells from healthy donors. Bars represent the mean ± SD. The Mann-Whitney U test was used to assess statistical significance: *P < .01; ***P < .001