Chromosome arm-specific multicolor FISH

Several systems for 24-color fluorescence in situ hybridization (FISH) have been developed and applied to karyotyping and detection of chromosomal abn ormalities. We have developed a 42-color multicolor FISH (mFISH) technique (armFISH), which permits the detection of chromosomal aberrations at the re solution of chromosome arms. The armFISH uses a commercially available mFIS H reagent kit (24XCyte, MetaSystems GmbH) supplemented with a set of differ entially labeled chromosome arm-specific painting probes (arm-kit, comprisi ng either p- or q-arms of all human chromosomes, except the p-arm of the ac rocentric- and Y chromosomes). The mFISH-probe cocktail and the arm-kit are combined and hybridized together to metaphase chromosomes. The armFISH is analyzed in two steps; first, the conventional mFISH image analysis is perf ormed, followed by the arm-kit analysis to reveal the chromosome arms invol ved. The examples demonstrate the utility of armFISH in defining chromosoma l rearrangements of human cancers. (C) 2001 Wiley-Liss, Inc.