Fluorescence In Situ Hybridization in Genotoxicity Testing

Abstract Exposure to physical and chemical genotoxic agents can damage DNA and produce DNA mutations. Quantifying these DNA mutations can reveal potential relationships between exposures and disease. The comet assay, micronucleus assay, and chromosomal aberration test used in genetic toxicology can quantify genetic damage predictive of heritable mutation and cancer. Integrating fluorescence in situ hybridization (FISH) into these conventional genetic toxicology assays improves their predictive value by identifying DNA alterations not detectable using standard methods. For example, gene-specific FISH probes incorporated into the comet assay enables discrimination of damage to DNA surrounding cancer-relevant genes compared with overall DNA damage. Integrating centromere-specific FISH probes into the micronucleus assay can differentiate clastogenic exposures from aneugenic exposures. Whole chromosome FISH readily identifies exposures that induce stable chromosome aberrations, particularly chromosome translocations, which are key to human disease but difficult to detect using other methods. Here, we discuss applications for integrating FISH into conventional assessments of DNA damage to augment genotoxicity studies and exposure assessments in humans.