Homozygous deletion mapping at 9p21 in bladder carcinoma defines a critical region within 2cM of IFNA.

We have screened 165 cases of primary transitional cell carcinoma of the bladder for loss of heterozygosity of markers on chromosome 9. High density deletion mapping was then carried out on a panel of 16 tumours with partial deletions of 9p using 15 microsatellite markers. Seven tumours had hemizygous deletions which included small interstitial losses and large terminal deletions. Homozygous deletions of one or more markers were identified in the remaining 9 tumours. By comparing the limits of hemi- and homozygous deletions in these tumours we have defined a single common region of 2cM flanked by IFNA and D9S171.