Conventional Karyotype and Fluorescence in situ Hybridization (FISH) Technology

Abstract

Karyotype analysis of cells has been in use for many years and has led to the causative genetic change in numerous clinical syndromes, including trisomy 21, Klinefelter, Turner, Prader-Willi and Angelman syndromes. The resolution of the test depends on the degree of condensation of the chromosomes in the karyotype, but even at high resolution (> 800 bands per haploid set) the changes identified are in the order of 5 Mb of DNA.  Fluorescence in situ hybridization (FISH) bridges the gap between the relatively low resolution of karyotype analysis and the very high resolution of DNA analysis. With FISH it is possible to identify smaller changes in individual cells. The size of the change identified correlates with the size of the probe, which vary from 120 kb to 600 kb in size. FISH is widely used to confirm deletions or duplications identified by newer methods, such as array analysis.   This review contains 8 figures, 3 tables, and 25 references. Keywords: Cytogenetics, chromosome, karyotype, chromosomal resolution, tissue culture, fluorescence, hybridization, probe