Early methods of deletion detection by two color fish

The first common approach for detecting deletions in both human metaphase and interphase cells is to apply two color FISH probe assays to cytogenetic preparations. This assay design has a centromere probe as a chromosome copy number control, and the gene probe or chromosome region probe of interest is labeled in a different color. In Figure 2 the commercially available PTEN FISH assay involving chromosome 10 is used as an example of two color FISH deletion detection to metaphase chromosomes (Figure 2A). "Spot counting "can" be used to determine the normal two spot non-deleted pattern (Figure 2B) seen when PTEN is deleted (Figure 2C) in intact interphase nuclei from a cytogenetic preparation.

Figure 2 Example of PTEN two color FISH in the detection of deletions (Competitor). In panel A the location of the green control Centromere probe and red PTEN probe are indicated using an ideogram of chromosome 10. In panel B two green spots in each nucleus indicates that the centromeres from both chromosome 10s are present and two red spots indicates that both copies of the PTEN gene are also present in each schematic nucleus. In panel C there are two green spots but on one red spot in each of the four nuclei. This indicates that one of the chromosome 10s has lost its copy of the PTEN gene by deletion. Note that the random spot distribution is random.