FISH mapping of the chromosome 11 and 18 breakpoints. (A) The hybridization signals of YAC 921F3 (green) and the BamHI fragment H of PAC 152M5 (red) are both split by the translocation in case 1. Signals of both probes are visible on the derivative chromosomes 11 and 18. (B) In case 2, fragment D of PAC 152M5 (red) shows split signals. The centromeric probes for chromosome 11 and 18 appear in green. (C) In case 1, PAC 532O24 (green) is seen on the normal chromosome 11 and on the derivative chromosome 11 (C), whereas this probe is split by the translocation in case 2 (D). The signals of the centromeric probes are shown in red.