Fluorescent in situ hybridization ("FISH") is a molecular diagnostic technology that uses a fluorescent-labeled probe to detect and localize the presence or absence of specific deoxyribonucleic acid ("DNA") sequences in chromosomes. The fluorescent-labeled probe, namely the FISH probe or DNA probe, is a synthetic piece of DNA that couples with a fluorescent indicator, so that the chromosomes or genes that it binds to can be directly visualized under a fluorescent microscope. FISH technology enables medical practitioners to visualize and locate DNA sequences in human cells for identifying chromosomal abnormalities. It is commonly used for prenatal and postnatal diagnosis, and confirmative diagnosis and prognosis of various cancers.