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 can be used to detect chimerism for XX and XY cells to evaluate successful engraftment post-bone marrow transplant. Serial FISH chimerism studies are useful in monitoring these patients.
FISH chimerism studies involve scoring of hybridization signals using chromosome X and Y specific DNA probes on interphase nuclei.
500 interphase nuclei are scored.
FISH is generally done in conjunction with chromosome analysis. If this is the case, no additional specimen is usually required.
If FISH for Chimerism Studies is to be performed without chromosome analysis:
- See specimen requirements for the type of specimen to be sent (i.e., bone marrow chromosome analysis)
- These studies may also be performed on cytospin slides, smears, and touch preps
Complete a Test Request Form and indicate FISH request in the “Cancer Specimens” section.