An optimized probe set for the detection of small Interchromosomal aberrations by use of 24- color FISH

Abstract

The rapid spread of the use of new 24-color karyotyping techniques has preceded their standardization. This is best documented by the fact that the exact resolution limits have not yet been defined. Indeed, it is shown here that a substantial proportion of interchromosomal aberrations will be missed by all multicolor karyotyping systems currently in use. We demonstrate that both the sensitivity and the specificity of 24-color karyotyping critically depend on the fluorochrome composition of chromosomes involved in an interchromosomal rearrangement. As a solution, we introduce a conceptual change in probe labeling. Seven-fluorochrome sets that overcome many of the current limitations are described, and examples of their applications are shown. The criteria presented here for an optimized probe-set design and for the estimation of resolution limits should have important consequences for preand postnatal diagnostics and for research applications.