Initiation-development modelling of allelic losses on chromosome 9 in multifocal bladder cancer

Multiple low-grade, low-stage superficial tumours were analysed for loss of heterozygosity (LOH) on chromosome 9 with 29 markers. Three consensus regi ons were found, one at 9p (9p21-22) and two at 9q (9q21-31 and 9q32-34). Ph ylogenetic trees were calculated for each patient using both designated chr omosome 9 regions and, separately, using individual microsatellite data. Re gional analysis suggested that multiple, equally important regions for blad der tumour initiation exist on chromosome 9. During the development of tumo urs all regions were eventually affected. The phylogenetic analyses with in dividual markers were used as molecular clocks to trace the ordering of tum ours. The results were compared with the physical locations of the tumours and a hypothetical development model was built. These are novel approaches which, to our knowledge, have not been used before. (C) 2000 Elsevier Scien ce Ltd. All rights reserved.