Under-representation of bladder transitional cell tumour 9q, lip and 14q LOH in urine and impact on molecular diagnosis

Background: To investigate whether the recently reported evidence of differences in the overall loss of heterozygosity (LOH) frequency between urine and tumour tissue in patients with transitional cell tumours (TCT) of the urinary bladder involved specific chromosomal sites, and their impact in diagnosis. Materials and Methods: Blood, tissue and urine specimens were obtained from 55 patients and 25 controls. Sixteen microsatellites were PCR-amplified and blindly analyzed for LOH through a laser-based capillary electrophoresis system. Results: Significant frequence differences between tumour tissue and urine sediment LOH were found in 9q and lip in non-invasive disease and 14q in invasive disease. There was no significant difference for all the other chromosomal arms analyzed. Conclusion: The contribution in the urine sediment of cells belonging to tumours of the same histological classification differs according to the specific genetic alterations these cells carry. Furthermore, the location regarding these differences could indicate regions involved in tumour exfoliation or apoptosis.