EVIDENCE OF CHROMOSOMAL INVERSION USING FLUORESCENCE IN-SITU HYBRIDIZATION TO STRETCHED DNA

The resolution of fluorescence in situ hybridization techniques (FISH) can be improved using techniques of DNA stretching. The so-called DIR VISH technique has been used to demonstrate the existence of an invers ion involving a small chromosomal segment of the long arm of chromosom e 14. This inversion was suspected, but not proven, in patients with f amilial Alzheimer disease. Two-colour FISH using YAC and cosmid probes allowed us to limit the rearranged region around YAC 964e2, which enc ompasses the Presenilin 1 (PR1) gene. The existence of small-sized inv ersions within the genome becomes, thus, open to microscope analysis. ((C) Academie des sciences/Elsevier, Paris.).