Molecular cytogenetic studies using fluorescence in situ hybridization (FISH) focus on specific chromosomes and chromosomal regions and, therefore, do not replace standard cytogenetic studies. Rather, these studies are used as an adjunct to chromosome analysis.
FISH studies involve analysis of hybridization signals using chromosome-specific DNA probes on metaphase spreads, interphase nuclei, paraffin embedded tissue, cytospin slides, smears, touch preps, and thin-prep cytology slides.
Indications for FISH in cancer cytogenetics include:
- Identification of aneuploidy in specimens with low mitotic index
- Detection of a masked BCR/ABL rearrangement associated with the 9;22 translocation (Philadelphia chromosome) and chronic myelogenous leukemia. Serial FISH studies are useful to establish initial frequencies of BCR/ABL-positive cells and provide comparative data for subsequent evaluation of the efficacy of various treatment regimens.
- Detection of a masked PML/RARA rearrangement in suspected APL
- Detection of the MLL rearrangement in infants less than 1 year of age with leukemia and a high WBC
- Detection of the TEL/AML1 rearrangement common in pediatric ALL
- Detection of the ALK rearrangement in lymphoma
- Detection of inversion 16 in AML
- Detection and/or clarification of complex rearrangements and breakpoints
- Monitoring response to treatment and detection of minimum residual disease
- Determining clonality using FISH on interphase cells
100 to 300 interphase cells are scored
See FISH Test List for currently available studies.
New disease-specific probes are continually being developed. Please contact CGL for more information.
- If FISH is done in conjunction with chromosome analysis, no additional specimen is required.
- See specimen requirements for type of specimen to be sent
- 3ml peripheral blood in sodium heparin tube (green top)
- Label specimen tube with patient’s name and a second identifier (ex: DOB, hospital ID).
- Maintain at room temperature and transport to Colorado Genetics Lab as soon as possible
- These studies may also be performed on paraffin embedded tissue, cytospin slides, smears, and touch preps. Provide 4-5 micron thick paraffin sections on Plus slides.