Examples of imbalances identified in stimulated and unstimulated CLL cells. (A) Partial M-FISH metaphase spread showing a deletion of 5p in patient 8 (Table 1). (B) An unstimulated interphase nucleus of this patient shows one signal for 5p (red) but 2 signals for 5q (yellow). (C) M-FISH identified der(17;18)(q10;q10) in patient 22 (Table 1). This rearrangement resulted in losses of 17p and 18p. (D-E) Interphase FISH was performed with 3 chromosome 17 and 18 probe sets. There was only one signal for a 17p subtelomere probe (yellow) (D), but there were 2 for 17q (yellow) (E), and in each hybridization there were 2 signals for a chromosome 17 centromere probe (red). (F-G) Similarly, we observed only one 18p subtelomere signal (yellow) (F), 2 18q signals (yellow) (G), and in each case 2 signals for 18 centromere (red). Images were obtained using a Leica DMRXA microscope (Leica, Wetzlar, Germany) with a 63 × 1.32 numeric aperture Plan Apo objective. Imaging medium was P-phenylenediamine dihydrochloride antifade solution. Images were captured using a Sensys CCD camera (Photometrics, Ottobrunn, Germany) and a Kodak KAF 1400 chip (Eastman Kodak, Rochester, NY), and were acquired using Leica Q-FISH and processed using Leica MCK software.