Allelic losses on chromosome 9 are common in a wide variety of human tumors
; moreover, two predisposing loci for some inherited cancer syndromes, i.e.
, familial malignant melanoma and Gorlin syndrome, have been identified on
this chromosome. To define the location of putative tumor suppressor genes
involved in cancer of the urinary bladder, 85 bladder cancers were examined
for allelic loss at 18 microsatellite loci on chromosome 9. Correlations w
ere also sought between loss of heterozygosity on chromosome 9 and several
clinicopathological parameters. Allelic loss was observed in 54 of the tumo
rs (64%) and deletion mapping identified two target regions; one at an inte
rval on 9p21 flanked by D9S736 and D9S165, and the other at an interval on
9q31-34 flanked by D9S58 and D9S61, No subtle mutation was detected in the
PTCH gene which lies in the latter interval. Allelic loss on chromosome 9 w
as observed frequently in low grade and non-invasive tumors as well as in t
umors of more advanced phenotype, Inactivation of tumor suppressor genes ly
ing in either of two regions of common deletion identified on chromosome 9
might affect carcinogenic mechanisms at an early stage of tumor development
in the urinary bladder.