Fluorescence in situ Hybridization General Principles and Clinical Application with Special Empha- sis to Interphase Diagnostics

Fluorescence in situ hybridization (FISH) is a molecular-cytogenetic investigation method and thus cov- ers a gap between classical cytogenetic and molecular-ge- netic techniques. By the broad spectrum of application pos- sibilities it leads to important new developments in basic and applied cytogenetics. It enables the labeling of whole chromosomes and defined chromosome regions and fur- thermore gene localization with single copy probes. FISH is a technique that allows DNA sequences to be detected on metaphase chromosomes, in interphase nuclei, in a tis- sue section, or in blastomeres and gametes. In basic scien- tific research special fields of application comprise charac- terization of somatic cell hybrids, analyses of meiosis and of karyotype evolution. In clinical and tumor cytogenetic it helps to identify chromosome rearrangements, marker chromosomes, chromosome mosaicism and specific tumor cell lines. Fluorescence in situ hybridization receives a spe- cial importance for interphase cytogenetics, which mainly covers the development in this field.