A rapid method for measuring pericentric inversions using fluorescence in situ hybridization (FISH).

We used three common fluorescent probes to measure pericentric inversion frequencies in 2.9 Gy 60Co gamma-irradiated human lymphocytes. For a given chromosome, the first probe is specific to one telomeric region, the second probe is specific to one subcentromeric region and the third probe is specific to the centromere. A pericentric inversion is made observable by the change in position (switching) of the fluorescent signals relative to the chromosome centromere. Our data showed equality between pericentric inversions and centric rings. The calculated whole-genome F-ratio of apparently simple translocations to pericentric inversions was 5.6.