A simple efficient method of sequential G-banding and fluorescence in situ hybridization.

Several methods of chromosome identification to be used in combination with G-banding by the trypsin technique with Giemsa staining (G-banding) and fluorescence in situ hybridization (FISH) have been developed in the past few years. Unfortunately, these methods are impractical to use in the clinical laboratory and can provide inconsistent results. We report a simple, efficient, and reliable method of G-banding and FISH for use in clinical cytogenetics. G-banded chromosomes are codenatured with a direct- or indirect-labeled DNA prove (by using either chromosome painting or a chromosome centromeric probe) followed by a hybridization and signal detection. The procedure requires no pretreatment or additional fixation and results in good preservation of chromosome morphology and good intensity of the FISH signal.