Fluorescence in situ hybridization FISH is the microscopic examination of cells or chromosomes for the presence or absence of a fluorescently tagged probe. The probe is specific for the region of a chromosome containing the genes for an explicit genetic syndrome or condition. Interphase analysis can also be undertaken as a rapid investigation for whole chromosome trisomy 13,18 or 21. Each FISH probe is specific to a region of DNA and therefore the syndrome or region for investigation must be specified on the referral card.

FISH Fluorescence in situ hybridization can be undertaken on preparations from cultured or uncultured cells (e.g. prenatal and postnatal investigations)

Application of Fluorescence in situ hybridization FISH include:

• Prenatal diagnosis.
• The identification of specific chromosomal abnormalities.
• Molecular cytogenetic of birth defect and mental retardation
• Cancer diagnosis.

For male infertility, screening tool like Sperm FISH is used for counseling couples with male factor infertility.