Mapping of leukaemia-associated breakpoints in chromosome band 3q21 using a newly established PAC contig

Chromosome aberrations affecting band 3q21 are associated with a particular ly poor prognosis in patients with acute myeloid leukaemia. To facilitate t he molecular characterization of such rearrangements, we established a PAC contig covering the relevant genomic region, Using these PACs as probes in fluorescence in situ hybridization (FISH) experiments, we showed that a num ber of 3q21 breakpoints in patient samples map to a previously defined 'bre akpoint cluster region'. Others, however, are located at varying distances centromeric of it. These results have important implications in the search for genes affected by 3q21 rearrangements.