Interphase FISH analysis of the p53 gene in MM: (A) Plasma cell from a patient without p53 deletion: Two hybridization signals with both probes (chromosome 17 centromere, green signals; p53, red signals) can be recognized. (B) Plasma cells from patient 3/FJ (Table 2) exhibiting a monoallelic deletion of p53 (probes as in A). (C) Interphase cell of patient 2/NN (compare Table 2: trisomy 17 by metaphase cytogenetics) hybridized with 3 probes: Chromosome 17 centromere (labeled with SPECTRUM-Green; large green signals), p53 (labeled with SPECTRUM-Orange; red signal), and distal 17p (D17S34 locus, labeled with digoxigenin and visualized with anti-digoxigenin-fluorescein isothiocyanate; small green signals). Presence of three signals for chromosome 17 centromere andD17S34, but only one signal for p53 indicating an interstitial deletion on 17p involving the p53 locus.