Representative results of 2-color FISH experiments and comparison of signal intensities in centromere alphoids. Two-color FISH was performed with SatIII (green) and D1Z7 (red) probes for normal (A-C) and abnormal (D-F) metaphases in Pt 6 and with D7Z2 (red), 97G24 (red), and D7Z1 (green) probes for normal (G-I) and abnormal (J-L) metaphases in Pt 16. 97G24 is a PAC probe located on 1q13 that helps detect trisomy of 1q. Images for FITC (B,E,H,K), Rhodamin (C,F,I,L), and both (A,D,G,J) were separately captured through a single triple-band-pass filter with an appropriate first-pass filter using a synchronized wheel filter device. 1 and 1′, 7 and 7′, and d indicate different alleles of chr1, chr7, and derivative chromosome, respectively. Captured images were subjected to measurement of signal intensities. Original magnification, × 1000. Intensity of the D1Z7 signal on derivative chromosome (*) is grossly reduced from its original intensity (**), as determined using SatIII intensity as a reference in Pt 6 (M) and Pt 8 (N). Likewise, D7Z1 signal on derivative chromosome (*) is also shown to decrease when compared with its original signal (**), as determined using D7Z2 intensity in Pt 16 (O). Arrows in panels A-L indicate the centromeres of chromosome 1, chromosome 7, or the derivative chromosome. Arrowheads in panel L point to the D7Z2 signals in order to distinguish these signals from the red signals of 97G24. Error bars represent the SD from 30 measurements in 1 patient.