IN-SITU HYBRIDIZATION ANALYSIS OF A HOMOGENEOUSLY STAINING REGION AT 11Q23-24 IN AN ACUTE MYELOID-LEUKEMIA (M5) USING YEAST ARTIFICIAL CHROMOSOMES

An example of a homogeneously staining region (hsr), occurring in an acute myeloid leukaemia (M5) on chromosome 11 in the region of bands q23-q24, has been analysed. In situ hybridisation using yeast artificial chromosome (YAC) DNA demonstrated that the amplification did not include the CD3 gene cluster and did not affect the human trithorax gene known to be disrupted by translocations at 11q23. In contrast, the amplification was shown to include the sequence D11S543 which has been previously mapped to chromosome band 11q24. High resolution analysis using confocal microscopy allowed the individual amplicons to be visualised, and it was shown that the hsr consisted of an 8-fold amplification of the region surrounding the probe D11S543. From previous estimates of human chromosome size it was possible to calculate that the hsr was composed of amplicons approximately 10 megabases in length. It was concluded that the region amplified did not extend as far as the translocation breakpoints occurring at 11q23 in acute leukaemias. (C) 1993 Wiley-Liss, Inc.