Multiple colors by fluorescence <i>in situ</i> hybridization using ratio-labelled DNA probes create a molecular karyotype

TLDR

Fluorescence in situ hybridization (FISH) is widely used for localizing genomic DNA fragments and identifying chromosomes by painting. The painting technique described here can identify small or complex chromosomal rearrangements and marker chromosomes in humans or any species with well‑defined chromosome‑specific libraries using a conventional fluorescence microscope. The authors demonstrate that half of the human chromosome set can be painted in twelve true colors using ratio‑labelled libraries, producing authentic color images and offering a versatile tool comparable to chromosome banding and high‑resolution prometaphase analysis.

Abstract

Fluorescence in situ hybridization (FISH) is now widely used for the localization of genomic DNA fragments, and the identification of chromosomes by painting. We now show that half of the chromosomal complement can be painted in twelve different colors by using human chromosome specific libraries carrying three distinct labels mixed in multiple ratios. The photographs are in 'real' color rather than 'colorized'. The painting technique described here can be used for the identification of small or complex chromosomal rearrangements and marker chromosomes in humans or in any other species for which well defined chromosome specific libraries exist in a laboratory equipped with a conventional fluorescence microscope. The versatility of this novel cytogenetic technology may well constitute an advancement comparable to the introduction of chromosome banding and high resolution analysis of chromosomes in prometaphase.