Fluorescent green cytoplasm allows identification of a plasma cell (patient no. 6a) and hybridization of DNA probes shows 2 copies for chr no. 9 (2 red signals; biotin-labeled probe) and 2 copies for chr no. 11 (2 green signals; FITC-labeled probe) [dual band-pass filter]. (B) in the same patient (no. 6a), one plasma cell is disomic for chr no. 9 (2 red signals) and trisomic for chr no. 11 (3 green signals) [dual band-pass filter]. (C) Using a dual band-pass filter, one plasma cell from patient no. 15a exhibits trisomy for chr no. 7 (FITC-labeled probe) and disomy for chr no. 9 (biotin-labeled probe): red signals close to the green ones lead to yellow fluorescence, and the use of single band-pass filters shows 2 red signals (D: texas-red filter) and 3 green ones (E: FITC filter). (F ) and (G) Plasma cells exhibiting trisomy for chr no. 7 (FITC-labeled probe) and trisomy for chr no. 9 (biotin-labeled probe), using the triple band-pass filter (patient no. 17b in F and no. 17a in G). (H) Plasma cell exhibiting 3 signals for chr no. 9 (biotin-labeled probe) and 2 signals for chr no. 7 (FITC-labeled probe) (patient no. 17a).