Comparative genomic hybridization is a molecular
cytogenetic method for analysing
copy number variations (CNVs) relative to
ploidy level in the DNA of a test sample compared to a reference sample, without the need for culturing cells. The aim of this technique is to quickly and efficiently compare two genomic DNA samples arising from two sources, which are most often closely related, because it is suspected that they contain differences in terms of either gains or losses of either whole
chromosomes or subchromosomal regions (a portion of a whole chromosome). This technique was originally developed for the evaluation of the differences between the chromosomal complements of solid tumor and normal tissue, and has an improved resoIution of 5-10
megabases compared to the more traditional cytogenetic analysis techniques of
giemsa banding and
fluorescence in situ hybridization (FISH) which are limited by the resolution of the microscope utilized.