Detailed deletion analysis of sporadic breast tumors defines an interstitial region of allelic loss on 17q25.

Whole genome analyses of breast tumors with polymorphic markers have detected nonrandom loss of heterozygosity on multiple chromosomes, providing clues to the locations of suspected tumor suppressor genes. Tumors are thought to initiate, progress, and metastasize as mutations accumulate in multiple growth-regulatory genes; thus, identification and characterization of these genes are critical to understanding and controlling breast tumorigenesis. To map more precisely a novel breast tumor suppressor gene that has been localized previously to distal 17q, we constructed a detailed deletion map of 17q25 by analyzing eight microsatellite markers on 39 sporadic primary breast tumors. The smallest overlapping region of interstitial loss was narrowed to approximately 3 cM and included D17S937/AFM107ye3, which showed the highest percentage of allelic loss (41%). These results provide a framework from which a genomic contig will be constructed and candidate transcripts will be analyzed.