ORDERING MARKERS IN THE REGION OF THE ATAXIA-TELANGIECTASIA GENE (11Q22-Q23) BY FLUORESCENCE IN-SITU HYBRIDIZATION (FISH) TO INTERPHASE NUCLEI

Fluorescence in situ hybridization (FISH) to interphase nuclei was per formed to order probes corresponding to bands 11q22-q23 where the atax ia-telangiectasia (AT) gene(s) have been located. Cosmid probes and on e phage probe previously localized to this chromosome II region by FIS H to metaphase chromosomes, were hy bridized to interphase nuclei of t he somatic cell hybrid Jla, which contains chromosome 11 as the only h uman chromosome. Two-color FISH was used with a centromeric reference probe marker. The following order was obtained: cen-D11S385 (CJ52.75)- CJ52.3-D11S384 (CJ52.193) CJ52.114-D11S424 (CJ52.77)-D11S132-NCAM-D11S 351 (CJ52.208)-tel. The validity of using the centromeric probe was il lustrated by showing that a probe corresponding to 11p13 hybridized mo re closely to the centromeric than a probe corresponding to 11q22-q23, and by using cosmids hybridized three by three.