Use of metaphase fluorescence in situ hybridization (FISH) to detect a microdeletion

The image shows metaphase FISH of cells from a patient with a deletion of chromosome 22q, which causes the DiGeorge/VCF syndrome.

• All chromosomes are stained with a blue-fluorescent dye.
• The VCF probes (green and red) detect two different regions of chromosome 22.
• In these cells, one copy of chromosome 22 is marked by both probes, but the other is only marked by the green probe, showing loss of the region of the long arm of the second copy of chromosome 22.